ANEURINE (thiamine) 



a correction was applied for the activity of any cleavage products 

 present in the sample. 



The lack of specificity was confirmed by H. F. Deutsch,* who 

 found that the pyrimidine half of aneurine was more active than 

 aneurine itself on yeast at low concentrations, but less active at high 

 concentrations. The pyrimidine and thiazole halves together were 

 almost as active as aneurine, whilst the thiazole half alone or 4-amino- 

 2-methyl-p3n-imidyl-5-methane sulphonic acid were less active. These 

 results are therefore not in complete agreement with those of Schultz 

 et al., who stated that the sulphite-cleavage products did not stimulate 

 the growth of yeasts ; the discrepancy may be due to the use of dif- 

 ferent strains. It is evident therefore that the yeast growth method 

 must be used with caution, especially when the test solution is sus- 

 pected to contain degradation products of aneurine. H. G. Obermeyer 

 and L. Chen,^*^ for example, showed that substantial amounts of 

 biologically available thiazole or pjnimidine derivatives remained in 

 foodstuffs in which aneurine had decomposed. 



Westenbrink et al.^'^ used the yeast fermentation method in rather 

 a novel form for the estimation of cocarboxylase in blood. The blood 

 was acidified to pH 3 and heated to 100° C. for 1} minutes, neutralised 

 to pH 6-2 and centrifuged. Alkali-washed brewers' yeast was added 

 to an aliquot portion of the solution, aneurine and a manganese salt 

 were then added and the suspension was incubated at 27-5° C. for 

 fifteen minutes to re-synthesise carboxylase. The yeast was then 

 centrifuged off, re-suspended in acetate buffer solution, pYL 5-6, and 

 reacted at 27-5° C. with sodium pyruvate. The amount of carbon 

 dioxide liberated was proportional to the cocarboxylase in the 

 blood. 



Although the yeast growth method, as generally used, is an aerobic 

 fermentation, aneurine can also be estimated by an anaerobic fer- 

 mentation. This was first demonstrated by L. Atkin et al.,^^ who 

 found that the addition of o-oi to 0-04 /xg. of aneinrine to 5 mg. of 

 yeast suspended in 3 ml. of medium considerably raised the anaerobic 

 carbon dioxide output during the second hour of incubation and that 

 the increase in fermentation by o-oi to 0-02 fig. of aneurine was pro- 

 portional to the vitamin concentration. The observation was con- 

 firmed by H. Laser,i3 ^]^q ^Iso showed that different yeasts behaved 

 differently, bakers' yeast giving a regular response and Torula utilis 

 no response at all. He also noted that in yeasts that responded with 

 an increase in anaerobic fermentation, aerobic fermentation was also 

 increased quantitatively by the same minute amounts of aneurine. 

 E. S. Josephson and R. S. Harris,^* using a Warburg manometer, were 

 able to estimate the aneurine content of tissue extracts containing as 

 little as 10-® g. per ml. 



34 



