Enzyme Nomenclature

Continued from EC to EC

EC 2.6.2 to EC 2.6.99


EC 2.6.2 Amidinotransferases
EC 2.6.3 Oximinotransferases
EC 2.6.99 Transferring Other Nitrogenous Groups

EC 2.6.2 Amidinotransferases

[EC Transferred entry: now EC glycine amidinotransferase (EC created 1961, deleted 1965)]

EC 2.6.3 Oximinotransferases


Accepted name: oximinotransferase

Reaction: pyruvate oxime + acetone = pyruvate + acetone oxime

Other name(s): transoximinase; oximase; pyruvate-acetone oximinotransferase; transoximase

Systematic name: pyruvate-oxime:acetone oximinotransferase

Comments: Acetaldehyde can act instead of acetone; D-glucose oxime can act instead of pyruvate oxime.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number: 9030-49-3


1. Yamafuji, K. and Eto, M. Chromatographic study of transoximase. Enzymologia 16 (1954) 247-255.

2. Yamafuji, K., Omura, H. and Miura, K. On the transoximase. Enzymologia 16 (1953) 75-80.

3. Yamafuji, K., Shimamura, M. and Omura, H. Measurement of transoximase action. Enzymologia 17 (1956) 359-362.

[EC created 1961]

2.6.99 Transferring Other Nitrogenous Groups


EC dATP(dGTP)—DNA purinetransferase
EC pyridoxine 5'-phosphate synthase
EC O-ureido-L-serine synthase
EC transferred, now EC


Accepted name: dATP(dGTP)—DNA purinetransferase

Reaction: (1) dATP + depurinated DNA = deoxyribose triphosphate + DNA
(2) dGTP + depurinated DNA = deoxyribose triphosphate + DNA

Systematic name: dATP(dGTP):depurinated-DNA purine transferase

Comments: The purine residue is transferred on to the apurinic site forming a normal glycosylic bond. dATP reacts at sites of the double-stranded depurinated DNA that lack adenine, and dGTP at sites that lack guanine.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:


1. Deutsch, W.A. and Linn, S. DNA binding activity from cultured human fibroblasts that is specific for partially depurinated DNA and that inserts purines into apurinic sites. Proc. Natl. Acad. Sci. USA 76 (1979) 141-144. [PMID: 218192]

2. Livneh, Z., Elad, D. and Sperling, J. Enzymatic insertion of purine bases into depurinated DNA in vitro. Proc. Natl. Acad. Sci. USA 76 (1979) 1089-1093. [PMID: 375225]

[EC created 1984]


Accepted name: pyridoxine 5'-phosphate synthase

Reaction: 1-deoxy-D-xylulose 5-phosphate + 3-amino-2-oxopropyl phosphate = pyridoxine 5'-phosphate + phosphate + 2 H2O

For diagram, click here

Other name(s): pyridoxine 5-phosphate phospho lyase; PNP synthase; PdxJ

Systematic name: 1-deoxy-D-xylulose-5-phosphate:3-amino-2-oxopropyl phosphate 3-amino-2-oxopropyltransferase (phosphate-hydrolysing; cyclizing)

Comments: In Escherichia coli, the coenzyme pyridoxal 5'-phosphate is synthesized de novo by a pathway that involves EC (erythrose-4-phosphate dehydrogenase), EC (4-phosphoerythronate dehydrogenase), EC (phosphoserine transaminase), EC (4-hydroxythreonine-4-phosphate dehydrogenase), EC (pyridoxine 5'-phosphate synthase) and EC (with pyridoxine 5'-phosphate as substrate). 1-Deoxy-D-xylulose cannot replace 1-deoxy-D-xylulose 5-phosphate as a substrate [3].

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 230310-47-1


1. Garrido-Franco, M. Pyridoxine 5'-phosphate synthase: de novo synthesis of vitamin B6 and beyond. Biochim. Biophys. Acta 1647 (2003) 92-97. [PMID: 12686115]

2. Garrido-Franco, M., Laber, B., Huber, R. and Clausen, T. Enzyme-ligand complexes of pyridoxine 5'-phosphate synthase: implications for substrate binding and catalysis. J. Mol. Biol. 321 (2002) 601-612. [PMID: 12206776]

3. Laber, B., Maurer, W., Scharf, S., Stepusin, K. and Schmidt, F.S. Vitamin B6 biosynthesis: formation of pyridoxine 5'-phosphate from 4-(phosphohydroxy)-L-threonine and 1-deoxy-D-xylulose-5-phosphate by PdxA and PdxJ protein. FEBS Lett. 449 (1999) 45-48. [PMID: 10225425]

4. Franco, M.G., Laber, B., Huber, R. and Clausen, T. Structural basis for the function of pyridoxine 5'-phosphate synthase. Structure 9 (2001) 245-253. [PMID: 11286891]

[EC created 2006]


Accepted name: O-ureido-L-serine synthase

Reaction: O-acetyl-L-serine + hydroxyurea = O-ureido-L-serine + acetate

Glossary: O-ureido-L-serine = (2S)-2-amino-3-[(carbamoylamino)oxy]propanoate
O-acetyl-L-serine = (2S)-3-acetyloxy-2-aminopropanoic acid

Other name(s): dcsD (gene name)

Systematic name: O-acetyl-L-serine:hydroxyurea 2-amino-2-carboxyethyltransferase

Comments: The enzyme participates in the biosynthetic pathway of D-cycloserine, an antibiotic substance produced by several Streptomyces species. Also catalyses EC, cysteine synthase.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:


1. Kumagai, T., Koyama, Y., Oda, K., Noda, M., Matoba, Y. and Sugiyama, M. Molecular cloning and heterologous expression of a biosynthetic gene cluster for the antitubercular agent D-cycloserine produced by Streptomyces lavendulae. Antimicrob. Agents Chemother. 54 (2010) 1132-1139. [PMID: 20086163]

2. Uda, N., Matoba, Y., Kumagai, T., Oda, K., Noda, M. and Sugiyama, M. Establishment of an in vitro D-cycloserine-synthesizing system by using O-ureido-L-serine synthase and D-cycloserine synthetase found in the biosynthetic pathway. Antimicrob. Agents Chemother. 57 (2013) 2603-2612. [PMID: 23529730]

[EC created 2013]

[EC Transferred entry: N6-L-threonylcarbamoyladenine synthase. Now EC, N6-L-threonylcarbamoyladenine synthase. (EC created 2014, deleted 2014)]

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