Thiaminase is an enzyme that metabolizes or breaks down thiamine into pyrimidine and thiazole. It is an antinutrient when consumed.
The old name was "aneurinase".
There are two types with different Enzyme Commission numbers:
- Thiamine pyridinylase, Thiaminase I (EC 2.5.1.2, InterPro: IPR030901)
- pyridine + thiamine <=> 5-(2-hydroxyethyl)-4-methylthiazole + heteropyrithiamine
- Secreted by Paenibacillus thiaminolyticus, an anaerobic organism that occurs in the human small intestine
- Aminopyrimidine aminohydrolase, Thinaminase II (EC 3.5.99.2, InterPro: IPR027574, IPR004305)
- 4-amino-5-aminomethyl-2-methylpyrimidine + H2O <=> 4-amino-5-hydroxymethyl-2-methylpyrimidine + NH2+
- H2O + thiamine <=> 4-amino-5-hydroxymethyl-2-methylpyrimidine + 5-(2-hydroxyethyl)-4-methylthiazole + H+
- Produced by a wide range of plants and bacteria. In these organisms, it is mainly responsible for salvage of thiamine pyrimidine from degradation products, rather than the breakdown of thiamine. In bacteria, it stays inside their cells.