150 BACTERIOLOGICAL CHEMISTRY 



sufficient to counteract the pantothenic acid present in 

 the blood. Mice, which normally have a considerably 

 higher content of pantothenic acid in the blood, are not 

 protected by such treatment because enough pantoyl- 

 taurine cannot be administered. Since human blood 

 has somewhat less pantothenic acid than rat blood it 

 should be possible to protect man against streptococci and 

 C. diphtherice, which is also sensitive to pantoyltaurine. 



The specific effects of metabolities on certain inhibitors 

 is illustrated in Table 14, due to Mcllwain, which shows 

 that inhibition is reversed only by the corresponding 

 metabolite. 



By testing the effect of a number of drugs, such as 

 sulphathiazole, containing the thiazole ring, it has been 

 shown that they can interfere with the decarboyxlation 

 of pyruvic acid (see p. 277), by Staph, aureus, E. coli, 

 yeast and by a carboxylase preparation from yeast. 

 Sulphathiazole is most effective against Staph, aureus 

 and E. coli, whilst sulphanilamide and sulphapyridine 

 have very little effect. The most active compound was 

 sulphanilamido-5-ethyl-4-thiazolone. 



NH2 



It will be remembered that co -carboxylase is aneurin 

 diphosphate (p. 43), 

 N=CH 





OH 

 which contains a thiazole ring. This may, in part, 

 explain the greater potency of sulphathiazole, as com- 

 pared with sulphanilamide, against many organisms. 



