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an enzyme that catalyzes the splitting of thiamine into a pyrimidine and a thiazole derivative.
1. An enzyme present in raw fish that destroys thiamin and may produce thiamin deficiency in animals on a diet largely composed of raw fish.
2. A hydrolase cleaving thiamin into a pyrimidine moiety (that is, 2-methyl-4-amino-5-hydroxymethylpyrimidine) and a thiazole moiety (that is, 4-methyl-5-(2'-hydroxyethyl)thiazole); the pyrimidine moiety may appear in the urine as pyramin. Synonym(s): thiaminase II