IUBMB Enzyme Nomenclature


Accepted name: aminopyrimidine aminohydrolase

Reaction: (1) 4-amino-5-aminomethyl-2-methylpyrimidine + H2O = 4-amino-5-hydroxymethyl-2-methylpyrimidine + NH3
(2) thiamine + H2O = 4-amino-5-hydroxymethyl-2-methylpyrimidine + 5-(2-hydroxyethyl)-4-methylthiazole

Other name(s):thiaminase (ambiguous); thiaminase II, tenA (gene name)

Systematic name: 4-amino-5-aminomethyl-2-methylpyrimidine aminohydrolase

Comments: Previously known as thiaminase II, this enzyme is involved in the regeneration of the thiamine pyrimidine from degraded products, rather than in thiamine degradation, and participates in thiamine salvage pathways.

Links to other databases: BRENDA, EAWAG-BBD, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 9024-80-0


1. Fujita, A., Nose, Y. and Kuratani, K. Second type of bacterial thiaminase. J. Vitaminol. (Kyoto) 1 (1954) 1-7. [PMID: 13243520]

2. Ikehata, H. Purification of thiaminase II. J. Gen. Appl. Microbiol. 6 (1960) 30-39.

3. Toms, A.V., Haas, A.L., Park, J.H., Begley, T.P. and Ealick, S.E. Structural characterization of the regulatory proteins TenA and TenI from Bacillus subtilis and identification of TenA as a thiaminase II. Biochemistry 44 (2005) 2319-2329. [PMID: 15709744]

4. Benach, J., Edstrom, W.C., Lee, I., Das, K., Cooper, B., Xiao, R., Liu, J., Rost, B., Acton, T.B., Montelione, G.T. and Hunt, J.F. The 2.35 Å structure of the TenA homolog from Pyrococcus furiosus supports an enzymatic function in thiamine metabolism. Acta Crystallogr. D Biol. Crystallogr. 61 (2005) 589-598. [PMID: 15858269]

5. Jenkins, A.H., Schyns, G., Potot, S., Sun, G. and Begley, T.P. A new thiamin salvage pathway. Nat. Chem. Biol. 3 (2007) 492-497. [PMID: 17618314]

6. Jenkins, A.L., Zhang, Y., Ealick, S.E. and Begley, T.P. Mutagenesis studies on TenA: a thiamin salvage enzyme from Bacillus subtilis. Bioorg. Chem. 36 (2008) 29-32. [PMID: 18054064]

7. French, J.B., Begley, T.P. and Ealick, S.E. Structure of trifunctional THI20 from yeast. Acta Crystallogr. D Biol. Crystallogr. 67 (2011) 784-791. [PMID: 21904031]

[EC created 1961, deleted 2011, modified 2011]

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