The vitamin, thiamine, is the precursor of thiamine pyrophosphate 

 or cocarboxylase which is the coenzyme for decarboxylation reactions such 

 as those catalyzed by pyruvic and a-ketoglutaric dehydrogenases. Thiamine 

 assays of fish tissue often have been included in surveys of the vitamin 

 content of fish (Higashi I9U8, Stansby 1953, Joshi et al. 1953, Hishida 

 and Nakano 195U, Braekkan et al. 1955, and Braekkan 1956). 



An enzyme found only in fish and invertebrates, thiaminase, splits 

 thiamine into pyrimidine and thiazole moieties (Krampitz and Woolley 19Ui 

 and Hamoir 1955 b). The distribution of thiaminase among marine inverte- 

 brates and marine vertebrates (Tatarskaya et al. 195U) and fresh-water 

 fishes (Chaet and Bishop 1952) has been studied. Sealock and TShite (19U9) 

 have made inhibition studies of this enzyme obtained from carp viscera. 

 Deolalkar and Sohonie (195U) found the thiaminase in fresh-water fish to 

 be remarkably different from that found in brackish- or salt-water species 

 with respect to activity measured over a wide range of pH. At least two 

 thiaminases are indicated in brackish- and salt-water fishs one with an 

 optimum activity in the alkaline range and the other with an optimum activ- 

 ity in the acid range. Attempts to fractionate these enzymes were un- 

 succesful, although the presence of a dialyzable coenzyme was demonstrated* 

 Kaminishi (1951) found thiaminase of shellfish and that of fish to be 

 similar and the respective ape— and coenzyme components to be interchange- 

 able. Tatarskaya et al. (1955) have made quantitative estimations of co- 

 thiaminase and have investigated some co-thiaminase-like compounds (Ta- 

 tarskaya 1952); however, the presence or absence of specific thiaminase 

 coenzymes in living cells is not known A rather complete review of 

 thiaminase has been made by Lee (19U8) and YudkLn (19u9). Harris (195l) 

 has tabulated the occurrence of this enzyme in many fish, mollusks, 

 mussels, clams, lobsters, shrimp, starfish, frogs, toads, and some warm- 

 blooded animals and has listed the tissues in which it is found. 



Fish possess an enzyme system capable of hydrolyzing folic acid, a 

 vitamin that has coenzymatic function (Jacobsohn and Deodata de Azevedo 

 19U9). The cobalt-containing vitamin, vitamin B^t which is required for 

 many reactions of intermediary metabolism, has been reported to occur in 

 shellfish and in red and white fish muscle by Hashimoto et al. (1953)» 

 Other workers reporting vitamin B12 in fish tissue include Peeler et al. 

 (1951), Hausmann and Mulli (1952), Karrick (1955), Braekkan et al. (1955)» 

 and Braekkan (1956). Pantothenic acid, which is a precursor of the im- 

 portant acetyl group carrier, coenzyme A, has been determined in red and 

 white muscle of tunafish by Braekkan et al. (1955)» 



Reference to these and other vitamins found in fish is given by 

 Stansby (1953) and Brown (1957). A definite coenzymatic role has not as 

 yet been established for many of these vitamins* 



Many enzymes are metal containing or metal activated. Iron, for 

 example, is found in the porphyrin moiety of the cytochromes. Magnesium 

 is involved in various kinase systems where phosphate is transferred from 

 ATP to substrate. Some of the common metals directly involved in inter- 

 mediary metabolism—such as iron, copper, magnesium, potassium, calcium, 

 and cobalt— have been measured in fish and marine invertebrate ^s^ff 

 (Coulson et al. 193U, Umemura 1951 c, Kruchakova 1952, Hausmann and Mulli 

 1952, and Stansby 1953). A general discussion of the mineral composition 

 of fishes may be found in The Physiology of Fishes (Brown 1957). 



21 



