Thiamin vitamin thiol form

Thiamine is among the least stable of the vitamins. The reaction catalysed by thiaminase 1, which is, for example, present in raw fish, lies in the cleavage of the thiamine molecule by an exchange reaction with nitrogen bases (such as nicotinic acid) or thiols (such as cysteine). Thiaminase 11 (found in some microorganisms) catalyses thiamine hydrolysis with the formation of the same products that form by non-enzymatic hydrolysis (Figure 5.10). 

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