FUNCTION 



the utilisation of glucose, and they concluded that pantothenic acid 

 was not a dissociable coenzyme for the glycolytic systems investigated. 

 Dorfman et al.^ found that calcium pantothenate increased the 

 oxygen uptake of Proteus morganii when lactic or pyruvic acid was 

 used as substrate, and concluded that pantothenic acid played a part 

 in the oxidation of pyruvic to acetic acid. G. M. Hills ^ made a 

 similar observation. These results were supported by the work of 

 Pilgrim et al.,^ who found that the oxidation of pyruvic acid by liver 

 tissue was retarded by a deficiency of pantothenic acid and biotin. 



M. G. Sevag and M.N. Green ^ suggested a different role for panto- 

 thenic acid, for they obtained evidence that it was in some way con- 

 nected with the metabolism of tryptophan. Staphylococcus aureus 

 required tryptophan for growth, but this could be replaced by panto- 

 thenic acid if glucose were also present. Moreover, the growth of 

 S. aureus was inhibited by sulphonamides in presence of glucose and 

 most amino acids, whether pantothenic acid was absent or not. The 

 inhibition was abolished, however, when tryptophan was added. 

 They interpreted this result to mean that sulphonamides inhibited the 

 reactions leading to the synthesis of tryptophan and that pantothenic 

 acid played a part in these reactions. So far, this suggestion has not 

 received support from the work of other investigators. 



A more satisfactory explanation of the function of pantothenic 

 acid is that of Lipmann et al.,^ who postulated that pantothenic acid 

 was the prosthetic group of a coenzyme necessary for acetylation. 



F. Lipmann ^ had previously isolated from liver a coenzyme that 

 catalysed the acetylation of aromatic amines and had shown ^ that it 

 also acetylated choline and was apparently identical with the activator 

 of choline acetylation reported by W. Feldberg and T. Mann,^ D. 

 Nachmansohn and M. Berman,^^ and M. A. Lipton.^^ A purified 

 preparation of this coenzyme, known as " Coenzyme A ", was found 

 to contain about lo % of pantothenic acid, and the activity of dif- 

 ferent preparations was found to run parallel with their pantothenic 

 acid contents. This theory is consistent with the observation of 



G. M. Hills ^ and Dorfman et al.^ that pantothenic acid takes part in 

 the oxidation of pyruvic acid to acetic acid, for G. D. Novelli and 

 F. Lipmann ^^ showed that the increased oxidation of pyruvic acid 

 that occurred when pantothenic acid was added to pantothenic acid- 

 deficient organisms was due to the synthesis of coenzyme A. In 

 L. arabinosus, 90 % of the pantothenic acid could be accounted for 

 as coenzyme A, which was present in negligible amounts in panto- 

 thenic acid-deficient organisms. The suggestion that pantothenic acid 

 is the prosthetic group of coenzyme A might also account for the con- 

 nection between pantothenic acid and choline (page 365). Pantothenic 

 acid increased acetylcholine formation by Lactobacillus plantarum}^'^ 



391 



