Thiaminase

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Thiaminase is an enzyme (EC 2.5.1.2) that metabolizes or breaks down thiamine into two molecular parts. It is found in bracken (brake) and other plants, as well as in raw fish, such as carp, goldfish, and also in a few strains of bacteria like Bacillus thiaminolyticus. Entomological thiaminase is found in an African silk worm in 2000. Its physiological meaning for the plant, fish, bacterial cell or insect is not known. It was first described as the cause of highly mortal ataxic neuropathy in fur producing foxes eating raw entrails of river fish like carp in 1941. The old name was Aneurinase. It is also known as the etiology of cerebrocortical necrosis of cattle and polioencephalomalasia of sheep eating thiaminase containing plants. It is also causing economical losses in raising fisheries, e.g. in yellowtail fed raw anchovy as a sole feed for a certain period, and also in sea bream and rainbow trout. The larvae of a wild silk worm Anaphe venata are being consumed in a rain forest district of Nigeria as a supplemental protein nutrition, and the heat resistant thiaminase in it is causing an acute seasonal ataxia with symptoms of intention tremor, cerebellar ataxia with gait, truncal ataxia and disturbance of consciousness or nystagmus in some cases.