III. BIOCHEMICAL SYSTEM 611 



TABLE IH^ 

 Relation of Coenzyme A Activity and Pantothenic Acid Content in Organs 



OF Rabbit 

 (All values are given per gram of wet weight of tissue) 



" Calculated by multiplication of the unit value by 0.65, the average pantothenic acid content in micro- 

 grams of a unit of coenzyme A. 



mann^^ could show that the chick almost completely utilized CoA-bound 

 pantothenic acid. Therefore, in contrast to most microorganisms, the ani- 

 mal body is able to utilize the vitamin fully when bound in the coenzyme. 



2. The Alkali Stability of "Natural Pantothenic Acid" 



It has been observed by various workers that natural pantothenic acid 

 in tissues and other fresh material resists alkali treatment much better 

 than free pantothenic acid, where the peptide bond between the /3-alanine 

 and pantoic acid is very labile to alkali (Jukes^^). Strong and King,*^ and, 

 independently, Baddiley,*^ have now explained this discrepancy. They 

 show that phosphorylation of pantothenic acid confers to it resistance 

 to alkali. Since pantothenic acid in Co A is phosphorylated, the alkali 

 resistance now is explained through the presence of the phosphorylated 

 pantothenic acid derivative coenzyme A. 



E. SPLIT PRODUCTS OF CoA AS MICROBIAL 

 GROWTH FACTORS 



In two instances a growth factor has been identified as a fragment of 

 CoA. These are the Acetobacter suhoxydans factor (PAC) of Cheldelin^^- ^^ 

 and the Lactobacillus hulgaricus factor (LBF, pantethine), of Snell and 

 Williams.^"' ^^' ■*" In a stricter sense, both factors are rather to be termed 

 growth stimulants. Acetobacter will grow relatively easily with pantothenic 

 acid, although with a pronounced lag period. The Lactobacillus bulgaricus 

 family responds poorly or not at all to small amounts of pantothenic acid 

 but will grow if rather large quantities are supplied. Since both organisms 



" D. M. Hegsted and F. Lipmann, J. Biol. Chem. 174, 89 (1948). 



56 T. E. King, I. G. Fels, and V. H. Cheldelin, J. Am. Chem. Soc. 71, 131 (1949). 



