ANEURINE (thiamine) 



thiocyanate and potassium dihydrogen phosphate had the same rela- 

 tively weak effect, but sodium fluoride, potassium sulphate and mag- 

 nesium chloride were more potent, and lajithammi nitrate still more 

 potent, inhibitors of this adsorptive phase. The second stage was of 

 longer duration and was very sensitive to pB. ; maximum absorption 

 occurred at pK 3-5 to 4-0. This stage was inhibited by iodoacetate or 

 azide and slightly by potassium cyanide or sodium fluoride. Absorp- 

 tion was also almost completely inhibited by 4-amino-5-aminomethyl- 

 2-methyl-pyrimidine, which was also found to inhibit the dephos- 

 phorylation of cocarboxylase by yeast phosphatase. It is therefore 

 suggested that phosphatase may be connected with this second phase 

 of aneurine absorption, which probably involves phosphorylation. 



Other Fungi 



The aneurine requirements of other fungi exhibit the same 

 wide variations that have been noted for the yeasts. Phy corny ces 

 Blakesleeanus, as already stated (page 35), fails to grow in the 

 absence of aneurine, and the weight of the mycelium formed on a 

 medium containing aneurine is, within limits, proportional to its 

 concentration. The test is highly specific and only closely related 

 analogues of aneurine (see page 122) give a response. ^^ An equi- 

 molecular mixture of the pyrimidine and thiazole moieties, however, 

 gave the same growth response as the corresponding amount of 

 aneurine,^^ though the organisms fail to grow when only one of these 

 fractions is present. 



Phytophthora cinnamomi ^^ and P. erythroseptica ^^ also require 

 aneurine for growth, but these fail to respond to a mixture of the two 

 halves of the molecule. Pythiomorpha gonapodioides ^^ will respond 

 either to aneurine or to the pyrimidine moiety alone, and it has been 

 suggested that by means of this organism in conjunction with P. 

 Blakesleeanus and P. erythroseptica, an estimate might be made of 

 the amounts of aneurine and of the thiazole and the pyrimidine halves 

 of the molecule in a mixture of all three. 



F. Kavanagh ^® observed that aneurine disappeared from cultures 

 in which Phy corny ces Blakesleeanus, Phytophthora cinnamomi, Mucor 

 Ramannianus or Sclerotium rolfori were grown and that with P. 

 Blakesleeanus the pyrimidine half of the aneurine molecule was liber- 

 ated and the thiazole half destroyed ; the addition of the thiazole 

 compound, but not the pjnrimidine compound, increased the growth 

 of the mould. P. cinnamomi utilised aneurine without destroying 

 either the thiazole or the pyrimidine moiety, whilst M. Ramannianus 

 synthesised the pyrimidine half and grew well in the presence of the 

 thiazole half. S. rolfori, when grown in solutions containing aneurine, 



108 



