EC 2 Transferases

NEW ENTRIES

EC 2.1.1.114

Recommended name: hexaprenyldihydroxybenzoate methyltransferase

Reaction: S-adenosyl-L-methionine + 3-hexaprenyl-4,5-dihydroxybenzoate = S-adenosyl-L-homocysteine + 3-hexaprenyl-4-hydroxy-5-methoxybenzoate

Other name(s): 3,4-dihydroxy-5-hexaprenylbenzoate methyltransferase; dihydroxyhexaprenylbenzoate methyltransferase

Systematic name: S-adenosyl-L-methionine:3-hexaprenyl-4,5-dihydroxylate O-methyltransferase

Comments: involved in the pathway of ubiquinone synthesis. This enzyme has been listed as EC 2.1.1.64 in some sequence databases; but that enzyme catalyses a different reaction.

References:

1. Clarke, C.F., Williams, W., Teruya, J.H. Ubiquinone biosynthesis in Saccharomyces cerevisiae. Isolation and sequence of COQ3, the 3,4-dihydroxy-5-hexaprenylbenzoate methyltransferase gene. J. Biol. Chem. 266 (1991) 16636-16641. [PMID: 1885593]

EC 2.1.1.115

Recommended name: (RS)-1-benzyl-1,2,3,4-tetrahydroisoquinoline N-methyltransferase

Reaction: S-adenosyl-L-methionine + (RS)-1-benzyl-1,2,3,4-tetrahydroisoquinoline = S-adenosyl-L-homocysteine + N-methyl-(RS)-1-benzyl-1,2,3,4-tetrahydroisoquinoline

Other name(s): norreticuline N-methyltransferase

Systematic name: S-adenosyl-L-methionine:(RS)-1-benzyl-1,2,3,4-tetrahydroisoquinolie N-methyltransferase

Comments: broad substrate specificity for (RS)-1-benzyl-1,2,3,4-tetrahydroisoquinolines; including coclaurine, norcoclaurine, isococlaurine, norarmepavine, norreticuline and tetrahydropapaverine. Both R- and S-enantiomers are methylated. The enzyme participates in the pathway leading to benzylisoquinoline alkaloid synthesis in plants. The physiological substrate is likely to be coclaurine. The enzyme was earlier termed norreticuline N-methyltransferase. However, norreticuline has not been found to occur in nature and that name does not reflect the broad specificity of the enzyme for (R,S)-1-benzyl-1,2,3,4-tetrahydroisoquinolines.

References:

1. Frenzel, T., Zenk, M.H. Purification and characterization of three isoforms of S-adenosyl-L-methionine: (R,S)-tetrahydrobenzyl-isoquinoline N-methyltransferase from Berberis koetineana cell cultures. Phytochemistry 29 (1990) 3491-3497.

EC 2.1.1.116

Recommended name: 3'-hydroxy-N-methyl-(S)-coclaurine 4'-O-methyltransferase

Reaction: S-adenosyl-L-methionine + 3'-hydroxy-N-methyl-(S)-coclaurine = S-adenosyl-L-homocysteine + (S)-reticuline

Systematic name: S-adenosyl-L-methionine:3'-hydroxy-N-methyl-(S)-coclaurine 4'-O-methyltransferase

Comments: involved in isoquinoline alkaloid metabolism in plants. The enzyme has also been shown to catalyse the methylation of (RS)-laudanosoline, (S)-3'-hydroxycoclaurine and (RS)-7-O-methylnorlaudanosoline.

References:

1. Frenzel, T., Zenk, M.H. S-Adenosyl-L-methionine: 3'-hydroxy-N-methyl-(S)-coclaurine 4'-O-methyltransferase, a regio- and stereoselective enzyme of the (S)-reticuline pathway. Phytochemistry 29 (1990) 3505-3511.

EC 2.1.1.117

Recommended name: (S)-scoulerine 9-O-methyltransferase

Reaction: S-adenosyl-L-methionine + (S)-scoulerine = S-adenosyl-L-homocysteine + (S)-tetrahydrocolumbamine

Systematic name: S-adenosyl-L-methionine:(S)-scoclaurine 9-O-methyltransferase

Comments: the product of this reaction is a precursor for protoberberine alkaloids in plants

References:

1. Muemmler, S., Rueffer, M., Nagakura, N., Zenk, M.H. S-Adenosyl-L-methionine:(S)-scoclaurine 9-O-methyltransferase, a highly stereo- and regiospecific enzyme in tetrahydroberberine biosynthesis. Plant Cell Reports 4 (1985) 36-39.

EC 2.1.1.118

Recommended name: columbamine O-methyltransferase

Reaction: S-adenosyl-L-methionine + columbamine = S-adenosyl-L-homocysteine + palmatine

Systematic name: S-adenosyl-L-methionine:columbamine O-methyltransferase

Comments: the product of this reaction is a protoberberine alkaloid that is widely distributed in the plant kingdom. This enzyme is distinct in specificity from 8-hydroxyquercetin 8-O-methyltransferase (EC 2.1.1.88).

References:

1. Rueffer, M., Amann, M., Zenk, M.H. S-Adenosyl-L-methionine:columbamine O-methyltransferase, a compartmentalized enzyme in protoberberine biosynthesis. Plant Cell Reports 3 (1986) 182-185.

EC 2.1.1.119

Recommended name: 10-hydroxydihydrosanguinarine 10-O-methyltransferase

Reaction: S-adenosyl-L-methionine + 10-hydroxydihydrosanguinarine = S-adenosyl-L-homocysteine + dihydrochelirubine

Systematic name: S-adenosyl-L-methionine:10-hydroxydihydrosanguinarine 10-O-methyltransferase

Comments: this reaction is part of the pathway for synthesis of benzophenanthridine alkaloids in plants.

References:

1. De-Eknamkul, W., Tanahashi, T., Zenk, M.H. Enzymic 10-hydroxylation and 10-O-methylation of dihydrosanguinarine in Eschscholtzia. Phytochemistry 31 (1992) 2713-2717.

EC 2.1.1.120

Recommended name: 12-hydroxydihydrochelirubine 12-O-methyltransferase

Reaction: S-adenosyl-L-methionine + 12-hydroxydihydrochelirubine = S-adenosyl-L-homocysteine + dihydromacarpine

Systematic name: S-adenosyl-L-methionine:12-hydroxydihydrochelirubine 12-O-methyltransferase

Comments: this reaction is part of the pathway for synthesis of benzophenanthridine alkaloid macarpine in plants.

References:

1. Kammerer, L., De-Eknamkul, W., Zenk, M.H. Enzymic 12-hydroxylation and 12-O-methylation of dihydrochelirubine in dihydromacarpine formation by Thalictrum bulgaricum. Phytochemistry 36 (1994) 1409-1416.

EC 2.1.1.121

Recommended name: 6-O-methylnorlaudanosoline 5'-O-methyltransferase

Reaction: S-adenosyl-L-methionine + 6-O-methylnorlaudanosoline = S-adenosyl-L-homocysteine + nororientaline

Systematic name: S-adenosyl-L-methionine:6-O-methylnorlaudanosoline 5'-O-methyltransferase

Comments: nororientaline is a precursor of the alkaloid papaverine.

References:

1. Rueffer, M., Nagakura, N., Zenk, M.H. A highly specific O-methyltransferase for nororientaline synthesis isolated from Argemone platyceras cell cultures. Planta Med. 49 (1983) 196-198.

EC 2.1.1.122

Recommended name: (S)-tetrahydroprotoberberine N-methyltransferase

Reaction: S-adenosyl-L-methionine + (S)-7,8,13,14-tetrahydroprotoberberine = S-adenosyl-L-homocysteine + cis-N-methyl-(S)-7,8,13,14-tetrahydroprotoberberine

Other name(s): tetrahydroprotoberberine cis-N-methyltransferase

Systematic name: S-adenosyl-L-methionine:(S)-7,8,13,14-tetrahydroprotoberberine cis-N-methyltransferase

Comments: involved in the biosynthesis of isoquinoline alkaloids in plants./

References:

1. Rueffer, M., Zumstein, G., Zenk, M.H. Partial purification and characterization of S-adenosyl-L-methionine:(S)-tetrahydroprotoberberine cis-N-methyltransferase from suspension-cultured cells of Eschscholtzia and Corydalis. Phytochemistry 29 (1990) 3727-3733.

EC 2.1.1.123

Recommended name: [cytochrome-c]-methionine S-methyltransferase

Reaction: S-adenosyl-L-methionine + [cytochrome c]-methionine = S-adenosyl-L-homocysteine + [cytochrome c]-S-methyl-methionine

Systematic name: S-adenosyl-L-methionine:[cytochrome-c]-methionine S-methyltransferase

Comments: the enzyme from Euglena gracilis methylates Met-65 of horse heart cytochrome c.

References:

1. Farooqui, J.Z., Tuck, M., Paik, W.K. Purification and characterization of enzymes from Euglena gracilis that methylate methionine and arginine residues of cytochrome c. J. Biol. Chem. 260 (1985) 537-545. [PMID: 2981218]

EC 2.1.1.124

Recommended name: [cytochrome-c]-arginine N-methyltransferase

Reaction: S-adenosyl-L-methionine + [cytochrome c]-arginine = S-adenosyl-L-homocysteine + [cytochrome c]-N-methyl-arginine

Systematic name: S-adenosyl-L-methionine:[cytochrome-c]-arginine N-methyltransferase

Comments: the enzyme from Euglena gracilis methylates Arg-38 of horse heart cytochrome c to form the N-monomethyl-arginine derivative. This enzyme was previously listed together with EC 2.1.1.25 and EC 2.1.1.26 as a single, now deleted, entry: Protein-arginine N-methyltransferase (EC 2.1.1.23).

References:

EC 2.1.1.125

Recommended name: (histone)-arginine N-methyltransferase

Reaction: S-adenosyl-L-methionine + [histone]-arginine = S-adenosyl-L-homocysteine + (histone)-N-methyl-arginine

Other name(s): histone protein methylase I; nuclear protein (histone) N-methyltransferase; protein methylase I

Systematic name: S-adenosyl-L-methionine:(histone)-arginine N-methyltransferase

Comments: the enzyme forms the N-monomethyl- and N,N'-dimethyl, but not the N,N-dimethyl-arginine derivatives. The name protein methylase I is misleading since it has been used for a number of enzymes with different specificities. This enzyme was previously listed together with EC 2.1.1.24 and 2.1.1.26 as a single, now deleted, entry: Protein-arginine N-methyltransferase (EC 2.1.1.23)

References:

1. Rajpurohit, R., Lee, S.O., Paik, W.K., Kim, S. Enzymatic methylation of recombinant heterogeneous nuclear RNP Protein A1. Dual substrate specificity for S-adenosylmethionine: histone-arginine-N-methyltransferase. J. Biol. Chem. 269 (1994) 1075-1082. [PMID: 8288564]

2. Rawal, N., Rajpurohit, R., Paik, W.K., Kim, S. Purification and characterization of S-adenosylmethionine-protein-arginine-N-methyltransferase from rat liver. Biochem. J. 300 (1994) 483-489. [PMID: 8002954]

EC 2.1.1.126

Recommended name: [myelin basic protein]-arginine N-methyltransferase

Reaction: S-adenosyl-L-methionine + [myelin basic protein]-arginine = S-adenosyl-L-homocysteine + [myelin basic protein]-N-methyl-arginine

Other name(s): myelin basic protein methylase I; protein methylase I

Systematic name: S-adenosyl-L-methionine:[myelin-basic-protein]-arginine N-methyltransferase

Comments: the enzyme from mammalian brain forms the N-monomethyl-, N,N-dimethyl- and N,N-dimethyl-arginine derivatives. The name protein methylase I is misleading since it has been used for a number of enzymes with different specificities. This enzyme was previously listed together with EC 2.1.1.24 and 2.1.1.25 as a single, now deleted, entry: Protein-arginine N-methyltransferase (EC 2.1.1.23).

References:

1. Ghosh, S.K., Paik, W.K., Kim, S. Purification and molecular identification of two protein methylases I from calf brain. Myelin basic protein and histone-specific enzyme. J. Biol. Chem. 263 (1988) 19024-19033. [PMID: 2461933]

EC 2.1.1.127

Recommended name: [ribulose-bisphosphate-carboxylase]-lysine N-methyltransferase

Reaction: S-adenosyl-L-methionine + [ribulose-1,5-bisphosphate-carboxylase]-lysine = S-adenosyl-L-homocysteine + [ribulose-1,5-bisphosphate-carboxylase]-N⁶-methyl-L-lysine

Other name(s): rubisco methyltransferase; ribulose-bisphosphate-carboxylase/oxygenase N-methyltransferase; ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit N-methyltransferase

Systematic name: S-adenosyl-L-methionine:[3-phospho-D-glycerate-carboxy-lyase (dimerizing)]-lysine N⁶-methyltransferase

Comments: the enzyme methylates Lys-14 in the large subunits of hexadecameric higher plant ribulose-bisphosphate-carboxylase (EC 4.1.1.39).

References:

1. Wang, P., Royer, M., Houtz, R.L. Affinity purification of ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit N-methyltransferase. Protein Expr. Purif. 6 (1995) 528-536. [PMID: 8527940]

2. Ying, Z., Janney, N., Houtz, R.L. Organization and characterization of the ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit N-methyltransferase gene in tobacco. Plant Mol. Biol. 32 (1996) 663-672.

EC 2.1.1.128

Recommended name: (RS)-norcoclaurine 6-O-methyltransferase

Reaction: S-adenosyl-L-methionine + (RS)-norcoclaurine = S-adenosyl-L-homocysteine + (RS)-coclaurine

Systematic name: S-adenosyl-L-methionine:(RS)-norcoclaurine 6-O-methyltransferase

Comments: norcoclaurine is 6,7-dihydroxy-1-[(4-hydroxyphenyl)methyl]-1,2,3,4-tetrahydroisoquinoline. The enzyme will also catalyse the 6-O-methylation of (RS)-norlaudanosoline to form 6-O-methyl-norlaudanosoline, but this alkaloid has not been found to occur in plants.

References:

1. Loeffler, S., Deus-Neumann, B., Zenk, M.H. S-Adenosyl-L-methionine: (RS)-coclaurine-N-methyltransferase from Tinospora cordifolia. Phytochemistry 38 (1995) 1387-1395.

2. Rueffer, M., Nagakura, N., Zenk, M.H. Partial purification and properties of S-adenosyl-L-methionine:(R),(S)-norlaudanosoline-6-O-methyltransferase from Argemone platyceras cell cultures. Planta Med. 49 (1983) 131-137.

3. Sato, F., Tsujita, T., Katagiri, Y., Yoshida, S., Yamada, Y. Purification and characterization of S-adenosyl-L-methionine:norcoclaurine-6-O-methyltransferase from cultured Coptis japonica cells. Eur. J. Biochem. 225 (1994) 125-131. [PMID: 7925429]

4. Stadler, R., Zenk, M.H. A revision of the generally accepted pathway for the biosynthesis of the benzotetrahydroisoquinoline reticuline. Liebigs Ann. Chem. (1990) 555-562.

EC 2.1.1.129

Recommended name: myo-inositol 4-O-methyltransferase

Reaction: S-adenosyl-L-methionine + myo-inositol = S-adenosyl-L-homocysteine + 4-methyl-myo-inositol

Systematic name: S-adenosyl-L-methionine:myo-inositol 4-O-methyltransferase

References:

1. Vernon, D.M., Bohnert, H.J. A novel methyl transferase induced by osmotic stress in the facultative halophyte Mesembryanthemum crystallinum. EMBO J. 11 (1992) 2077-2085. [PMID: 1600940]

EC 2.1.1.130

Recommended name: precorrin-2 C²⁰-methyltransferase

Reaction: S-adenosyl-L-methionine + precorrin-2 = S-adenosyl-L-homocysteine + precorrin-3A

Systematic name: S-adenosyl-L-methionine:precorrin-4 C²⁰-methyltransferase

References:

1. Roessner, C.A., Warren, M.J., Santander, P.J., Atshaves, B.P., Ozaki, S., Stolowich, N.J., Iida, K., Scott, A.I. Expression of Salmonella typhimurium enzymes for cobinamide synthesis. Identification of the 11-methyl and 20-methyl transferases of corrin biosynthesis. FEBS Lett. 301 (1992) 73-78. [PMID: 1451790]

2. Roessner, C.A., Spencer, J.B., Ozaki, S., Min, C., Atshaves, B.P., Nayar, P., Anousis, N., Stolowich, N.J., Holderman, M.T., Scott, A.I. Overexpression in Escherichia coli of 12 vitamin B₁₂ biosynthetic enzymes. Protein Extr. Purif. 6 (1995) 155-163. [PMID: 7606163]

3. Debussche, L., Thibaut, D., Cameron, B., Crouzet, J., Blanche, F.J. Biosynthesis of the corrin macrocycle of coenzyme B₁₂ in Pseudomonas denitrificans. J. Bacteriol. 175 (1993) 7430-7440. [PMID: 8226690]

EC 2.1.1.131

Recommended name: precorrin-3B C¹⁷-methyltransferase

Reaction: S-adenosyl-L-methionine + precorrin-3B = S-adenosyl-L-homocysteine + precorrin 4

Other name(s): precorrin-3 methyltransferase

Systematic name: S-adenosyl-L-methionine:precorrin-3B C¹⁷-methyltransferase

References:

1. Scott, A.I., Roessner, C.A., Stolowich, N.J., Spencer, J.B., Min, C., Ozaki, S.I. Biosynthesis of vitamin B12. Discovery of the enzymes for oxidative ring contraction and insertion of the fourth methyl group. FEBS Lett. 331 (1993) 105-108. [PMID: 8405386]

2. Debussche, L., Thibaut, D., Cameron, B., Crouzet, J., Blanche, F.J. Biosynthesis of the corrin macrocycle of coenzyme B₁₂ in Pseudomonas denitrificans. J. Bacteriol. 175 (1993) 7430-7440. [PMID: 8226690]

EC 2.1.1.132

Recommended name: precorrin-6Y C^5,15-methyltransferase (decarboxylating)

Reaction: 2 S-adenosyl-L-methionine + precorrin-6Y = 2 S-adenosyl-L-homocysteine + precorrin-8X + CO2

Other name(s): precorrin-6 methyltransferase; precorrin-6Y methylase

Systematic name: S-adenosyl-L-methionine:1-precorrin-6Y C^5,15-methyltransferase (C¹²-decarboxylating)

Comments: the enzyme from Pseudomonas denitrificans has S-adenosyl-L-methionine-dependent methyltransferase and decarboxylase activities.

References:

1. Blanche, F., Famechon, A., Thibaut, D., Debussche, L., Cameron, B., Crouzet, J. Biosynthesis of vitamin B12 in Pseudomonas denitrificans: the biosynthetic sequence from precorrin-6Y to precorrin-8X is catalyzed by the cobL gene product. J. Bacteriol. 174 (1992) 1050-1052. [PMID: 1732195]

EC 2.1.1.133

Recommended name: precorrin-4 C¹¹-methyltransferase

Reaction: S-adenosyl-L-methionine + precorrin-4 = S-adenosyl-L-homocysteine + precorrin 5

Other name(s): precorrin-3 methylase

Systematic name: S-adenosyl-L-methionine:precorrin-4 C¹¹ methyltransferase

Comments: catalyses the methylation of C¹¹ in precorrin-4 to form precorrin-5.

References:

1. Crouzet, J., Cameron, B., Cauchois, L., Rigault, S., Rouyez, M.C., Blanche, F., Thibaut D., Debussche, L. Genetic and sequence analysis of an 8.7-kilobase Pseudomonas denitrificans fragment carrying eight genes involved in transformation of precorrin-2 to cobyrinic acid. J. Bacteriol. 172 (1990) 5980-5990. [PMID: 2211521]

2. Roth, J.R., Lawrence, J.G., Rubenfield, M., Kieffer-Higgins, S., Church, G.M. Characterization of the cobalamin (vitamin B12) biosynthetic genes of Salmonella typhimurium. J. Bacteriol. 175 (1993) 3303-3316. [PMID: 8501034]

EC 2.1.1.134

Recommended name: myo-inositol 6-O-methyltransferase

Reaction: S-adenosyl-L-methionine + myo-inositol = S-adenosyl-L-homocysteine + 1D-4-O-methyl-myo-inositol

Systematic name: myo-inositol 6-O-methyltransferase

Comments: the enzyme from Vigna umbellata (Fabaceae) is highly specific for S-adenosyl-L-methionine. The enzyme also methylates 1L-1,2,4/3,5-cyclohexanepentol, 2,4,6/3,5-pentahydroxycylohexanone, D,L-2,3,4,6/5-pentacyclohexanone and 2,2'-anhydro-2-C-hydroxymethyl-myo-inositol at lower rates than that of myo-inositol. Showed no activity on other naturally occurring isomeric inositols and inositol O-methyl-ethers. Strongly inhibited by Mn^II, Zn^II, Cu^II and sulfhydryl group inhibitors.

References:

1. Wanek, W., Richter, A. Purification and characterization of myo-inositol 6-O-methyltransferase from Vigna umbellata Ohwi et Ohashi. Planta 197 (1995) 427-434.

2. Vernon, D.M., Bohnert, H.J. A novel methyl transferase induced by osmotic stress in the facultative halophyte Mesembryanthemum crystallinum. EMBO J. 11 (1992) 2077-2085. [PMID: 1600940]

EC 2.1.1.135

Recommended name: [methionine synthase]-cobalamin methyltransferase (cob(II)alamin reducing)

Reaction: [methionine synthase]-cob(II)alamin + NADPH₂ + S-adenosyl methionine = [methionine synthase]-methylcob(I)alamin + S-adenosylhomocysteine + NADP.

Other name(s): methionine synthase cob(II)alamin reductase (methylating); methionine synthase reductase

Systematic name: S-adenosylmethionine:[methionine synthase]-cobalamin methyltransferase (Co^II reducing)

Comments: a flavoprotein. Electrons are probably transferred from NADPH₂ to FAD to FMN.

References:

1. Leclerc, D., Wilson, A., Dumas, R., Gafuik, C., Song, D., Watkins, D., Heng, H.H.Q., Rommens, J.M., Scherer, S.W., Rosenblatt, D.S., Gravel, R.A. Cloning and mapping of a cDNA for methionine synthase reductase, a flavoprotein defective in patients with homocystinuria. Proc. Natl. Acad. Sci. USA, 95 (1998) 3059-3064. [PMID: 9501215]

EC 2.3.1.147

Recommended name: glycerophospholipid arachidonoyl-transferase (CoA-independent)

Reaction: 1-organyl-2-arachidonoyl-sn-glycero-3-phosphocholine + 1-organyl-2-lyso-sn-glycero-3-phosphoethanolamine = 1-organyl-2-arachidonyl-sn-glycero-3-phosphoethanolamine + 1-organyl-2-lyso-sn-glycero-3-phosphocholine

Systematic name: 1-organyl-2-arachidonyl-sn-glycero-3-phosphocholine:1-organyl-2-lyso-sn-glycero-3-phosphoethanolamine arachidonoyltransferase (CoA-independent)

Comments: catalyses the transfer of arachidonate and other polyenoic fatty acids from intact choline or ethanolamine-containing glycerophospholipids to the sn-2 position of a lyso-glycerophospholipid. The organyl group on sn-1 of the donor or acceptor molecule can be alkyl, acyl or alk-1-enyl. The term 'radyl' has sometimes been used to refer to such substituting groups. Differs from EC 2.3.1.148 in not requiring CoA and in its specificity for poly-unsaturated acyl groups.

References:

1. Robinson, M., Blank, M.L., Snyder, F. Acylation of lysophospholipids by rabbit alveolar macrophages. Specific CoA-dependent and CoA-independent reactions. J. Biol. Chem. 260 (1985) 7889-7895. [PMID: 4008481]

2. Snyder, F., Lee, T.C., Blank, M.L. The role of transacylases in the metabolism of arachidonate and platelet-activating factor. Prog. Lipid Res. 31 (1992) 65-86. [PMID: 1641397]

EC 2.3.1.148

Recommended name: glycerophospholipid acyltransferase (CoA-dependent)

Reaction: 1-organyl-2-acyl-sn-glycero-3-phosphocholine + 1-organyl-2-lyso-sn-glycero-3-phosphoethanolamine = 1-organyl-2-acyl-sn-glycero-3-phosphoethanolamine + 1-organyl-2-lyso-sn-glycero-3-phosphocholine

Systematic name: 1-organyl-2-acyl-sn-glycero-3-phosphocholine:1-organyl-2-lyso-sn-glycero-3-phosphoethanolamine acyltransferase (CoA-dependent)

Comments: catalyses the transfer of fatty acids from intact choline- or ethanolamine-containing glycerophospholipids to the sn-2 position of a lyso-glycerophospholipid. The organyl group on sn-1 of the donor or acceptor molecule can be alkyl, acyl or alk-1-enyl. The term 'radyl' has sometimes been used to refer to such substituting groups. Differs from EC 2.3.1.147 in requiring CoA and not favouring the transfer of polyunsaturated acyl groups.

References:

1. Irvine, R.F., Dawson, R.M.C. Transfer of arachidonic acid between phospholipids in rat liver microsomes. Biochem. Biophys. Res. Commun. 91 (1979) 1399-1405. [PMID: 526311]

2. Robinson, M., Blank, M.L., Snyder, F. Acylation of lysophospholipids by rabbit alveolar macrophages. Specific CoA-dependent and CoA-independent reactions. J. Biol. Chem. 260 (1985) 7889-7895. [PMID: 4008481]

3. Snyder, F., Lee, T.C., Blank, M.L. The role of transacylases in the metabolism of arachidonate and platelet-activating factor. Prog. Lipid Res. 31 (1992) 65-86. [PMID: 1641397]

EC 2.3.1.149

Recommended name: platelet-activating factor acetyltransferase

Reaction: 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine + 1-organyl-2-lyso-sn-glycero-3-phospholipid = 1-organyl-2-lyso-sn-glycero-3-phosphocholine + 1-alkyl'-2-acetyl-sn-glycero-3-phospholipid

Other name(s): PAF acetyltransferase

Systematic name: 1-alkyl-2-acyl-sn-glycero-3-phosphocholine:1-organyl-2-lyso-sn-glycero-3-phospholipid acetyltransferase

Comments: catalyses the transfer of the acetyl group from 1-alkyl-2-acyl-sn-glycero-3-phosphocholine (platelet-activating factor) to the sn-2 position of lyso-glycerophospholipids containing ethanolamine, choline, serine, inositol or phosphate groups at the sn-3 position as well as to sphingosine and long-chain fatty alcohols. The organyl group can be alkyl, acyl or alk-1-enyl (sometimes also collectively referred to as 'radyl').

References:

1. Lee, T.C., Uemura, Y., Snyder, F. A novel CoA-independent transacetylase produces the ethanolamine plasmalogen and acyl analogs of platelet-activating factor (PAF) with PAF as the acetate donor in HL-60 cells. J. Biol. Chem. 267 (1992) 19992-20001. [PMID: 1400315]

EC 2.3.1.150

Recommended name: salutaridinol 7-O-acetyltransferase

Reaction: acetyl-CoA + salutaridinol = CoA + 7-O-cetylsalutaridinol

Systematic name: acetyl-CoA:salutaridinol 7-O-acetyltransferase

Comments: the enzyme is present in the poppy, Papaver somniferum. At higher pH values the product, 7-O-acetylsalutaridinol, spontaneously closes the 4 [arrow to right] 5 oxide bridge by allylic elimination to form the morphine precursor thebaine

References:

1. Lenz, R., Zenk, M.H. Closure of the oxide bridge in morphine biosynthesis. Tetrahedron Lett. 35 (1994) 3897-3900.

2. Lenz, R., Zenk, M.H. Acetyl-CoA:salutaridinol 7-O-acetyltransferase from Papaver somniferum plant cell cultures. The enzyme catalyzing the formation of thebaine in morphine biosynthesis. J. Biol. Chem. 270 (1995) 31091-31096. [PMID: 8537369]

EC 2.3.1.151

Recommended name: benzophenone synthase

Reaction:3 malonyl-CoA + 3-hydroxybenzoyl-CoA = 4 CoA + 2,3',4,6-tetrahydroxybenzophenone + 3 CO₂

Systematic name: malonyl-CoA:3-hydroxybenzoyl-CoA malonyltransferase

Comments: involved in the biosynthesis of plant xanthomes. Benzoyl-CoA can replace 3-hydroxybenzoyl-CoA.

References:

1. Beerhues, L. Benzophenone synthase from cultured cells of Centaurium erythraea. FEBS Lett. 383 (1996) 264-266. [PMID: 8925910]

EC 2.3.1.152

Recommended name: alcohol O-cinnamoyltransferase

Reaction: 1-O-trans-cinnamoyl- [beta] -D-glucopyranose + ROH = alkyl cinnamate + glucose

Systematic name: 1-O-trans-cinnamoyl- [beta] -D-glucopyranose:alcohol O-cinnamoyltransferase

Comments: acceptor alcohols (ROH) include methanol, ethanol and propanol. No cofactors are required as 1-O-trans-cinnamoyl- [beta] -D-glucopyranose itself is an "energy-rich" (activated) acyl-donor, comparable to CoA-thioesters. 1-O-trans-Cinnamoyl- [beta] -D-gentobiose can also act as the acyl donor, but with much less affinity.

References:

1. Mock, H.-P., Strack, D. Energetics of uridine 5'-diphosphoglucose-hydroxy-cinnamic acid acyl-glucotransferase reaction. Phytochemistry 32 (1993) 575-579.

2. Latza, S., Gansser, D., Berger, R.G. Carbohydrate esters of cinnamic acid from fruits of Physalis peruviana, Psidium guajava and Vaccinium vitis IDAEA. Phytochemistry 43 (1996) 481-485.

EC 2.3.1.153

Recommended name: anthocyanin 5-aromatic acyltransferase

Reaction: hydroxycinnamoyl-CoA + anthocyanidin-3,5-diglucoside = CoA + anthocyanidin 3-glucoside-5-hydroxycinnamoylglucoside

Systematic name: hydroxycinnamoyl-CoA:anthocyanidin 3,5-diglucoside 5-O-glucoside-6'''-O-hydroxycinnamoyltransferase

Comments: transfers hydroxycinnamoyl group only to the C-5 glucoside of anthocyanin. Malonyl-CoA cannot act as a donor.

References:

1. Fujiwara, H., Tanaka, Y., Fukui, Y., Nakao, M., Ashikari, T., Kusumi, T. Anthocyanin 5-aromatic acyltransferase from Gentiana triflora. Purification, characterization and its role in anthocyanin biosynthesis. Eur. J. Biochem. 249 (1997) 45-51. [PMID: 9363752]

EC 2.4.1.207

Recommended name: xyloglucan:xyloglucosyl transferase

Reaction: breaks a [beta] -(1 [arrow to right] 4) bond in the backbone of a xyloglucan and transfers the xyloglucanyl segment on to O-4 of the non-reducing terminal glucose residue of an acceptor, which can be a xyloglucan or an oligosaccharide of xyloglucan

Other name(s): endo-xyloglucan transferase; xyloglucan endotransglycosylase

Systematic name: xyloglucan:xyloglucan xyloglucanotransferase

Comments: does not use cello-oligosaccharides as either donor or acceptor.

References:

1. Fry, S.C., Smith, R.C., Renwick, K.F., Hodge, S.C., Matthews, K.J. Xyloglucan endotransglycosylase, a new cell wall-loosening activity from plants. Biochem. J. 282 (1992) 821-828. [PMID: 1554366]

2. Nishitani, K., Tominaga, R. Endoxyloglucan transferase, a novel class of glucosyltransferase that catalyzes transfer of a segment of xyloglucan to another xyloglucan molecule. J. Biol. Chem. 267 (1992) 21058-21064. [PMID: 1400418]

3. De Silva, J., Jarman, C.D., Arrowsmith, D.A., Stronach, M.S., Chengappa, S., Sidebottom, C., Reid, J.S.G. Molecular characterisation of a xyloglucan-specific endo-1,4- [beta] -D-glucanase (xyloglucan endotransglucosylase) from nasturtium seeds. Plant J. 3 (1993) 701-711.

4. Lorences, E.P., Fry, S.C. Xyloglucan oligosaccharides with at least two [alpha] -D-xylose residues act as acceptor substrates for xyloglucan endotransglycosylase and promote the depolymerisation of xyloglucan. Plant Physiol. 88 (1993) 105-112.

EC 2.4.1.208

Recommended name: diglucosyl diacylglycerol synthase

Reaction: UDP-glucose + 1,2-diacyl-3-O-( [alpha] -D-glucopyranosyl)-sn-glycerol = 1,2-diacyl-3-O-( [alpha] -D-glucopyranosyl(1 [arrow to right] 2)-O- [alpha] -D-glucopyranosyl)sn-glycerol + UDP

Other name(s): monoglucosyl diacylglycerol (1 [arrow to right] 2) glucosyltransferase; MGlcDAG (12) glucosyltransferase; DGlcDAG synthase

Systematic name: UDP-glucose:1,2-diacyl-3-O-( [alpha] -D-glucopyranosyl)-sn-glycerol (1 [arrow to right] 2) glucosyltransferase

Comments: the enzyme from Acholeplasma laidlawii requires Mg²⁺.

References:

1. Karlsson, O.P., Rytomaa, M., Dahlqvist, A., Kinnunen, P.K., Wieslander, A. Correlation between bilayer lipid dynamics and activity of the diglucosyldiacylglycerol synthase from Acholeplasma laidlawii membranes. Biochemistry 35 (1996) 10094-10102. [PMID: 8756472]

EC 2.5.1.43

Recommended name: nicotianamine synthase

Reaction: 3 S-adenosyl-L-methionine = 3 5'-S-methyl-5'-thioadenosine + nicotianamine

Systematic name: S-adenosyl-L-methionine:S-adenosyl-L-methionine:S-adenosyl-methionine alanyltransferase

References:

1. Higuchi, K., Kanazawa, K., Nishizawa, N.-K., Chino, M., Mori, S. Purification and characterization of nicotianamine synthase from Fe-deficient barley root. Plant Soil 165 (1994) 173-179.

EC 2.5.1.44

Recommended name: homospermidine synthase

Reaction: putrescine + putrescine = sym-homospermidine + NH₃₊

Systematic name: putrescine:putrescine 4-aminobutyltransferase (ammonia-forming)

Comments: requires NAD, which functions catalytically. In the presence of putrescine, spermidine can function as a donor of the aminobutyl group, in which case, propanediamine is released instead of ammonia

References:

1. Tait, G.H. The formation of homospermidine by an enzyme from Rhodopseudomonas viridis. Biochem. Soc. Trans. 7 (1979) 199-200. [PMID: 437275]

2. Böttcher, F., Ober, D., Hartmann, T. Biosynthesis of pyrrolizidine alkaloids: putrescine and spermidine are essential substrates of enzymatic homospermidine formation. Can. J. Chem. 72 (1994) 80-85.

3. Yamamoto, S., Nagata, S., Kusaba, K. Purification and characterization of homospermidine synthase in Acinetobacter tartarogens ATCC 31105. J. Biochem. 114 (1993) 45-49. [PMID: 8407874]

4. Srivenugopal, K.S., Adiga, P.R. Enzymatic synthesis of sym-homospermidine in Lathyrus sativus T (grass pea) seedlings. Biochem. J. 190 (1980) 461-464. [PMID: 7470060]

EC 2.7.1.143

Recommended name: diphosphate-purine nucleoside kinase

Reaction: diphosphate + a purine nucleoside = monophosphate + a purine mononucleotide

Other name(s): pyrophosphate-purine nucleoside kinase

Systematic name: diphosphate:purine nucleoside phosphotransferase

Comments: the enzyme from the Acholeplasma class of Mollicutes catalyses the conversion of adenosine, guanosine and inosine to AMP, GMP and IMP. ATP cannot substitute for diphosphate as a substrate.

References:

1. Tryon, V.V., Pollack, D. Purine metabolism in Acholeplasma laidlawii B: novel PPi-dependent nucleoside kinase activity. J. Bacteriol. 159 (1984) 265-270. [PMID: 6330034]

2. Tryon, V.V., Pollack, J.D. Distinctions in Mollicutes purine metabolism: pyrophosphate-dependent nucleoside kinase and dependence on guanylate salvage. Int. J. Systematic Bacteriol. 35 (1985) 497-501.

EC 2.7.1.144

Recommended name: tagatose-6-phosphate kinase

Reaction: ATP + D-tagatose 6-phosphate = ADP + D-tagatose 1,6-bisphosphate

Systematic name: ATP:D-tagatose-6-phosphate 1-phosphotransferase

References:

1. Nobelmann, B., Lengeler, J.W. Sequence of the gat operon for galactitol utilization from a wild-type strain EC3132 of Escherichia coli. Biochim. Biophys. Acta 1262 (1995) 69-72. [PMID: 7772602]

EC 2.7.7.59

Recommended name: [protein-PII] uridylyltransferase

Reaction: UTP + [protein-PII] = diphosphate + uridylyl-[protein-PII]

Other name(s): PII uridylyl-transferase; uridyl removing enzyme

Systematic name: UTP:[protein-PII] uridylyltransferase

Comments: the enzyme uridylylates and de-uridylylates the small trimeric protein PII. The enzymes from E. coli and S. typhimurium have been wrongly identified, in some databases, as EC 2.7.7.12 (UDP-glucose-hexose-1-phosphate uridylyltransferase), from which it differs greatly in both reaction catalysed and sequence.

References:

1. Garcia, E., Rhee, S.G. Cascade control of Escherichia coli glutamate synthetase. Purification and properties of PII uridylyltransferase and uridylyl-removing enzyme. J. Biol. Chem. 258 (1983) 2246-2253. [PMID: 6130097]

2. Van Heeswijk, W., Rabenberg, M., Westerhoff, H., Kahn, D. The genes of the glutamate synthetase adenylylation cascade are not regulated by nitrogen in Escherichia coli. Mol. Microbiol. 9 (1993) 443-457. [PMID: 8412694]

EC 2.7.8.23

Recommended name: carboxyvinyl-carboxyphosphonate phosphorylmutase

Reaction: 1-carboxyvinyl carboxyphosphonate = 3-(hydrohydroxyphosphoryl)pyruvate + CO₂

Systematic name: 1-carboxyvinyl carboxyphosphonate phosphorylmutase (decarboxylating)

Comments: catalyses the transfer and decarboxylation of the carboxy(hydroxy)phosphoryl group, HOOC-P(O)(OH)- (phosphoryl being a 3-valent group), in the formation of an unusual C-P bond that is involved in the biosynthesis of the antibiotic bialaphos.

References:

1. Pollack, S.J., Freeman, S., Pompliano, D.L and Knowles, J.R. Cloning, overexpression and mechanistic studies of carboxyphosphonoenolpyruvate mutase from Streptomyces hygroscopicus. Eur. J. Biochem. 209 (1992) 735-743. [PMID: 1330557]

2. Anzai, H., Murakami, T., Imai, S., Satoh, A., Nagaoka, K., Thompson, C.J. Transcriptional regulation of bialaphos biosynthesis in Streptomyces hygroscopicus. J. Bacteriol. 169 (1987) 3482-3488. [PMID: 3611020]

EC 2.7.9.3

Recommended name: selenide, water dikinase

Reaction: ATP + selenide + H₂O = AMP + selenophosphate + phosphate

Other name(s): selenophosphate synthase

Systematic name: ATP:selenide, water phosphotransferase

Comments: Mg²⁺-dependent enzyme identified in Escherichia coli

References:

1. Veres, Z., Tsai, L., Scholz, T.D., Politino, M., Balaban, R.S., Stadtman, T.C. Synthesis of 5-methylaminomethyl-2-selenouridine in tRNAs: ³¹P NMR studies show the labile selenium donor synthesised by the selD gene product contains selenium bonded to phosphorus. Proc. Natl. Acad. Sci. U.S.A. 89 (1992) 2975-2979. [PMID: 1557403]

EC 2.8.1.6

Recommended name: biotin synthase

Reaction: dethiobiotin + sulfur = biotin

Systematic name: dethiobiotin:sulfur sulfurtransferase

Comments: an iron-sulfur enzyme. The sulfur donor has been unidentified to date - it is not elemental sulfur or an iron-sulfur cluster.

References:

1. Shiuan, D., Campbell, A. Transcriptional regulation and gene arrangement of Escherichia coli, Citrobacter freundii and Salmonella typhimurium biotin operons. Gene 67 (1988) 203-211. [PMID: 2971595]

2. Zhang, S., Sanyal, I., Bulboaca, G.H., Rich, A., Flint, D.H. The gene for biotin synthase from Saccharomyces cerevisiae: cloning, sequencing, and complementation of Escherichia coli strains lacking biotin synthase. Arch. Biochem. Biophys. 309 (1994) 29-35. [PMID: 8117110]

EC 2.9.1.1

Recommended name: L-seryl-tRNA^Sec selenium transferase

Reaction: L-seryl-tRNA^Sec + selenophosphate = L-selenocysteinyl-tRNA^Sec + H₂O + phosphate

Other name(s): L-selenocysteinyl-tRNA^Selsynthase; L-Selenocysteinyl-tRNA^Secsynthase selenocysteine synthase; cysteinyl-tRNA^Sel-selenium transferase; cysteinyl-tRNA^Sec-selenium transferase

Systematic name: selenophosphate:L-seryl-tRNA^Selselenium transferase

Comments: a pyridoxal 5'-phosphate enzyme identified in Escherichia coli. Recognizes specifically tRNA^Sec-species. Binding of tRNA^Sec also occurs in the absence of the seryl group. 2-Aminoacryloyl-tRNA, bound to the enzyme as an imine with the pyridoxal phosphate, is an intermediate in the reaction. Since the selenium atom replaces oxygen in serine, the product may also be referred to as L-selenoseryl-tRNA^Sel. The abbreviation Sel has also been used for selenocysteine but Sec is preferred.

References:

1. Forchhammer, K., Böck, A. Selenocysteine from Escherichia coli. Analysis of the reaction sequence. J. Biol. Chem. 266 (1991) 6324-6328. [PMID: 2007585]

AMENDMENTS TO EXISTING ENTRIES

EC 2.1.1.23 Deleted entry: protein-arginine N-methyltransferase. Now listed as EC 2.1.1.124, 2.1.1.125 and 2.1.1.126.

EC 2.1.1.63

Recommended name: methylated-DNA-[protein]-cysteine S-methyltransferase

Reaction: DNA (containing 6-O-methylguanine) + [protein]-L-cysteine = DNA (without 6-O-methylguanine) + protein S-methyl-L-cysteine

Systematic name: DNA-6-O-methylguanine-[protein]-L-cysteine S-methyltransferase

Comments: this protein is involved in the repair of alkylated DNA. It acts only on the alkylated DNA (cf. EC 3.2.2.20 and EC 3.2.2.21). Since the acceptor protein is the `enzyme' itself and the S-methyl-L-cysteine derivative formed is relatively stable, the reaction is not catalytic.

References:

1. Foote, R.S., Mitra, S., Pal, B.C. Demethylation of O⁶-methylguanine in a synthetic DNA polymer by an inducible activity in Escherichia coli. Biochem. Biophys. Res. Commun. 97 (1981) 654-659.

2. Olsson, M., Lindehl, T. Repair of alkylated DNA in Escherichia coli. Methyl group transfer from O⁶-methylguanine to a protein cysteine residue. J. Biol. Chem. 255 (1980) 10569. [PMID: 7000780]

3. Pegg, A.E., Byers, T.L. Repair of DNA containing O⁶-alkylguanine. FASEB J. 6 (1992) 2302-2310. [PMID: 1544541]

EC 2.3.1.82

Recommended name: Aminoglycoside N⁶'-acetyltransferase

Reaction: acetyl-CoA + kanamycin-B = CoA + N⁶'-acetylkanamycin-B

Systematic name: acetyl-CoA:kanamycin-B N⁶'-acetyltransferase

Comments: the antibiotics kanamycin A, kanamycin B, neomycin, gentamicin C1a, gentamicin C2 and sisomicin are substrates. The antibiotics gentamicin, tobramycin and neomycin, but not paromomycin, can also act as acceptors. The 6-amino group of the purpurosamine ring is acetylated.

References:

1. le Goffic, F., Martel, A. La résistance aux aminosides provoquée par une isoenzyme la kanamycine acétyltransférase. Biochimie (Paris) 56 (1974) 893-897. [PMID: 4614862]

2. Benveniste, R., Davies, J.E. Enzymatic acetylation of aminoglycoside antibiotics by Escherichia coli carrying an R factor. Biochemistry 10 (1971) 1787-1796. [PMID: 4935296]

3. Dowding, J.E. Mechanisms of gentamicin resistance in Staphylococcus aureus. Antimicrob. Agents Chemother. 11 (1977) 47-50. [PMID: 836013]

EC 2.3.1.55 Deleted entry: Identical to EC 2.3.1.82

EC 2.4.1.37

Recommended name: glycoprotein-fucosylgalactoside [alpha] -galactosyltransferase

Reaction: UDPgalactose + glycoprotein- [alpha] -L-fucosyl-(1,2)-D-galactose = UDP + glycoprotein- [alpha] -D-galactosyl-(1,3)-[ [alpha] -L-fucosyl(1,2)]-D-galactose

Systematic name: UDPgalactose:glycoprotein- [alpha] -L-fucosyl-(1,2)-D-galactose 3- [alpha] -D-galactosyltransferase

Comments: acts on blood group substance, and can use a number of 2-fucosyl-galactosides as acceptors.

References:

1. Race, C., Ziderman, D., Watkins, W.M. An [alpha] -D-galactosyltransferase associated with the blood-group B character. Biochem. J. 107 (1968) 733-735.

EC 2.4.1.40

Recommended name: glycoprotein-fucosylgalactoside [alpha] -N-acetylgalactosaminyltransferase

Reaction: UDP-N-acetyl-D-galactosamine + glycoprotein- [alpha] -L-fucosyl-(1,2)-D-galactose = UDP + glycoprotein-N-acetyl- [alpha] -D-galactosaminyl-(1,3)-[[[apha]]-L-fucosyl-(1,2)]-D-galactose

Other name(s): A-transferase

Systematic name: UDP-N-acetyl-D-galactosamine:glycoprotein- [alpha] -L-fucosyl-(12)-D-galactose 3-N-acetyl-D-galactosaminyltransferase

Comments: acts on blood group substance, and can use a number of 2-fucosyl-galactosides as acceptors

References:

1. Kobata, A., Grollman, E.F., Ginsburg, V. An enzymic basis for blood type A in humans. Arch. Biochem. Biophys. 124 (1968) 609-612. [PMID: 5661629]

2. Takeya, A., Hosomi, O., Ishiura, M. Complete purification and characterization of a-3-N-acetylgalactosaminyltransferase encoded by the human blood group A gene. J. Biochem. (Tokyo) 107 (1990) 360-368. [PMID: 2341371]

3. Yates, A.D., Feeny, J., Donald, A.S.R., Watkins, W.M. Characterisation of a blood-group A-active tetrasaccharide synthesised by a blood-group B gene-specified glycosyltransferase. Carbohydr. Res. 130 (1984) 251-260. [PMID: 6434182]

EC 2.4.1.162

Recommended name: aldose [beta] -D-fructosyltransferase

Reaction: [alpha] -D-aldosyl¹ [beta] -D-fructoside + D-aldose² = D-aldose¹ + [alpha] -D-aldosyl² [beta] -D-fructoside

Systematic name: [alpha] -D-aldosyl- [beta] -D-fructoside:aldose 1- [beta] -fructosyltransferase

References:

1. Cheetham, P.S.J., Hacking, A.J., Vlitos, M. Synthesis of novel disaccharides by a newly isolated fructosyl transferase from Bacillus subtilis. Enzyme Microb. Technol. 11 (1989) 212-219.

EC 2.7.1.25

Recommended name: adenylylsulfate kinase

Reaction: ATP + adenylylsulfate = ADP + 3'-phosphoadenylylsulfate

Systematic name: ATP:adenylylsulfate 3'-phosphotransferase

Comments: The human phosphoadenosine-phosphosulfate synthase (PAPS) system is a bifunctional enzyme (fusion product of two catalytic activities; ATP sulfurylase that catalyses the formation of adenosine 5'-phosphosulfate (APS) from ATP and inorganic sulfate. The second step is catalysed by the APS kinase portion of 3'-phosphoadenosine 5'-phosphosulfate (PAPS) synthase, which involves the formation of PAPS from enzyme bound APS and ATP. This is in contrast to what is found in bacteria, yeast, fungi and plants, where the formation of PAPS is carried out by two individual polypeptides, ATP sulfurylase (EC 2.7.7.4) and APS kinase (EC 2.7.1.25).

References:

1. Bandurski, R.S., Wilson, L.G., Squires, C.L. The mechanism of "active sulfate" formation. J. Am. Chem. Soc. 78 (1956) 6408-6409.

2. Robbins, P.W., Lipmann, F. Isolation and identification of active sulfate. J. Biol. Chem. 229 (1957) 837-851.

3. Venkatachalam, K.V., Akita, H., Strott, C. Molecular cloning, expression and characterization of human bifunctional 3'-phosphoadenosine-5'-phosphosulfate synthase and its functional domains. J. Biol. Chem. 273 (1998) 19311-19320. [PMID: 9668121]

EC 2.7.7.4

Recommended name: sulfate adenylyltransferase

Reaction: ATP + sulfate = diphosphate + adenylylsulfate

Other name(s): ATP-sulfurylase; sulfurylase

Systematic name: ATP:sulfate adenylyltransferase adenylyltransferase

References:

1. Bandurski, R.S., Wilson, L.G., Squires, C.L. The mechanism of "active sulfate" formation. J. Am. Chem. Soc. 78 (1956) 6408-6409

2. Hilz, H., Lipmann, F. The enzymatic activation of sulfate. Proc. Natl Acad. Sci. USA 41 (1955) 880-890.

EC 2.8.1.5

Recommended name: thiosulfate-dithiol sulfurtransferase

Reaction: thiosulfate + dithioerythritol = sulfite + 4,5-cis-dihydroxy-1,2-dithiacyclohexane (i.e. oxidized dithioerythritol) + sulfide

Other name(s): thiosulfate reductase

Systematic name: thiosulfate:dithioerythritol sulfurtransferase.

Comments: the enzyme from Chlorella shows very little activity towards monothiols such as glutathione and cysteine (cf. EC 2.8.1.3). The enzyme probably transfers the sulfur atom onto one thiol group to form -S-S^-, and sulfide is spontaneously expelled from this by reaction with the other thiol group. May be identical with EC 2.8.1.1.

References:

1. Schmidt, A., Erdle, I., Gamon, B. Isolation and characterization of thiosulfate reuctase from the green alga Chlorella fusca. Planta 162 (1984) 243-249.

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