698 THE BIOCHEMISTRY OF B VITAMINS 



toms suggestive of thiamine deficiency after about ten days, and death 

 ensued about twenty days later. If treated orally with 0.5 mg of thiamine 

 per day, animals showing severe anorexia, emaciation and polyneuritis 

 promptly recovered. The toxicity was not decreased when the air-dried 

 fern was heated at 105° C in air for 18 hours. The causative agent is 

 essentially insoluble in ethyl ether and in acetone, but appears to be 

 slightly soluble in 92 per cent ethyl alcohol. 



Table 46. The Inhibition of the De phosphorylation of Cocarboxylase in Yeast. 



Analogue Inhibition Index Reference 



Thiamine hydrochloride 15° 80 



between 0.2 and 20 81 



3-(2'-Methyl-4'-amino-5'-pyrimidylmethyl)- 75° 80 



4-methyl-5-(/3-hydroxypropyl)thiazolium 



chloride 

 2-Methyl-4-amino-5-aminomethylpyrimidine 100-150" 80 



hydrochloride 50-150 81 



2-Methyl-4-amino-5-thioformamidomethyl- 400" 80 



pyrimidine hydrochloride 

 2-Methyl-4-hydroxy-5-thioformamidomethyl- b 80 



pyrimidine hydrochloride 



° Ochoa and Peters 80 reported that these compounds stimulated the carboxylase system of yeast which 

 had been washed with alkaline phosphate buffer solution. Westenbrink 81 , et al. showed that the apparent 

 ' stimulation" was due to inhibition of the dephosphorylation of the cocarboxylase. These inhibition indices 

 are calculated from the data of Ochoa and Peters on the assumption that 50% "stimulation" corresponded 

 to 50% inhibition of dephosphorylation of the cocarboxylase present and they represent the ratio 

 moles of inhibitor , . , . „ .. .. . ,. „ 



= ; 1 which gives .)(.)' r "stimulation. 



moles of cocarboxylase 



b Ochoa and Peters reported that this compound did not "stimulate" the carboxylase system. 



The Chastek paralysis of foxes was shown by Green, Carlson and 

 Evans 86 to be caused by diets containing large amounts of raw fish, 

 which apparently contained a substance capable of inactivating the 

 thiamine in the feed and thus caused a thiamine deficiency. Later in- 

 vestigations demonstrated that a similar effect was produced in chicks 87 

 and in cats. 88 In each case, the toxicity could be overcome by the admin- 

 istration of large amounts of thiamine. The toxic substance was found to 

 be an enzyme, 89 and it was shown by Krampitz, Woolley and White 90 

 to cleave the thiamine molecule at the methylene bridge, liberating ulti- 

 mately 2-methyl-4-amino-5-hydroxymethylpyrimidine and 4-methyl-5- 

 (/?-hydroxyethyl)thiazole. The thiazole component was liberated directly, 

 but the pyrimidine portion apparently was first converted to an inter- 

 mediate and liberated in a subsequent reaction. This was confirmed by 

 Hennessy, Warner, Falk and Truhlar, 91 who isolated a crystalline inter- 

 mediate after the destruction of thiamine by clam tissue. Analysis indi- 

 cated that the molecular formula was CsH1eN.iO3S.2HCl but the structure 

 of the compound was not reported. Sealock and Davis 92 found that 

 m-nitroaniline and m-aminobenzoic acid stimulated the Chastek paralysis 

 thiaminase in vitro, and they concluded that this effect was due to the 



