Thiaminase

Thiaminase is an enzyme that metabolizes or breaks down thiamine into two molecular parts.

The old name was "Aneurinase". [cite journal |author=Fujita A, Nose Y, Kozuka S et al. |title=Studies on thiaminase |journal=J.Biol.Chem. |volume=196 |issue= |pages=289–295 |year=1952 |pmid= ]

There are two types: [http://www.ansci.cornell.edu/plants/toxicagents/thiaminase.html Thiaminases ] ]
* (EC number|2.5.1.2)
* (EC number|3.5.99.2)

ources

Source include:
* Bracken (brake), Nardoo and other plants. [cite journal |author=NcCleary BV and Chick BF. |title=The purification and properties of a thiaminaseI from Nardoo (Marsilea drummondii) |journal=Phytochemistry |volume=16 |issue= |pages=207–213 |year=1977|doi=10.1016/S0031-9422(00)86787-4 ]
* Some fish including carp and goldfish. [cite journal |author=Boś M, Kozik A |title=Some molecular and enzymatic properties of a homogeneous preparation of thiaminase I purified from carp liver |journal=J Protein Chem |volume=19 |issue=2 |pages=75–84 |year=2000 |pmid=10945431 |doi=10.1023/A:1007043530616]
* A few strains of bacteria like Bacillus thiaminolyticus [cite journal |author=Wittliff JL and Airth RL. |title=The extracellular thiaminase I of Bacillus thiaminolyticus I. Purification and physicochemical properties |journal=Biochemistry |volume=7 |issue= |pages=736–44 |year=1968|doi=10.1021/bi00842a032] , Bacillus aneurinolyticus [cite journal |author=Nakatsuka T, Suzuki K, Nakano Y, Kitaoka S. |title=Physicochemical properties of intracellular thiaminase II of Bacillus aneurinolyticus |journal=Vitamins (Japan) |volume=62 |issue= |pages=15–22 |year=1988 |pmid= ] , or Bacillus subtilis. [cite journal |author=Toms A, Haas A, Park J, Begley T, Ealick S |title=Structural characterization of the regulatory proteins TenA and TenI from Bacillus subtilis and identification of TenA as a thiaminase II |journal=Biochemistry |volume=44 |issue=7 |pages=2319–29 |year=2005 |pmid=15709744 |doi=10.1021/bi0478648]
* An African silk worm, Anaphe venata [cite journal |author=Nishimune T, Watanabe Y, Okazaki H, Akai H. |title=Thiamin is decomposed due to Anaphe spp. entomophagy in seasonal ataxia patients in Nigeria |journal=J.Nutr. |volume=130 |issue= |pages=1625–28 |year=2000 |pmid= ]

Effects

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.

It is also known as the etiology of cerebrocortical necrosis of cattle and polioencephalomalasia of sheep eating thiaminase containing plants. [cite journal |author=Ramos J, Marca C, Loste A, García de Jalón J, Fernández A, Cubel T |title=Biochemical changes in apparently normal sheep from flocks affected by polioencephalomalacia |journal=Vet Res Commun |volume=27 |issue=2 |pages=111–24 |year=2003 |pmid=12718505 |doi=10.1023/A:1022807119539] [cite journal |author=Evans WC. |title=Thiaminases and their effects on animals |journal=Vitamins and Hormones |volume=33 |issue= |pages=467–504 |year=1975 |doi=10.1016/S0083-6729(08)60970-X ]

It was once 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 same problem is being studied in a natural food chain system. [cite journal |author=Fisher JP, Brown SB, Wooster GW and Bowser PR. |title=Maternal blood, egg and larval thiamin levels correlate with larval survival in landlocked Atlantic salmon |journal=J.Nutr. |volume=128 |issue= |pages=2456–66 |year=1998 |pmid= ]

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 cerebellar ataxia. [cite journal |author=Adamolekun B, Adamolekun WE, Sonibare AD and Sofowora G.|title=A double-blind, placebo-controlled study of the efficacy of thiamin hydrochloride in a seasonal ataxia in Nigerians |journal=Neurology |volume=44 |issue= |pages=549–51 |year=1944 |pmid= ]

In 1860-61 - Burke and Wills were the first Europeans to cross Australia south to north; on their return they subsisted primarily on raw nardoo-fern and died of beriberi because of the extremely high thiaminase content in an otherwise thiamine-poor diet. ]

References