614 PANTOTHENIC ACID 



In conclusion, it seems worth mentioning that the two fragments of CoA, 

 which are active as growth factors, mirror, in the direction of synthesis, 

 the two degrading steps essential for the liberation of pantothenic acid 

 from CoA. The Acetohacter factor is destroyed by intestinal phosphatase 

 and the Lactobacillus hulgaricus factor by bird liver "peptidase," the com- 

 bination of which is necessary to liberate pantothenic acid fully for the assay 

 with Lactobacillus arabinosus or Proteus morgani}'^ 



F. THE METABOLIC FUNCTION OF CoA 

 1. Distribution of CoA 



All living material so far tested for CoA was found to contain this co- 

 enzyme in variable amounts.^"- ^^ The highest content in animal tissues is 

 found in the liver. Rat liver assays from 100 to 250 units per gram wet 

 weight. In Table II, which appears on p. 611, the enzymatically assayed 

 CoA content of various animal tissues is compared with the total amount 

 of pantothenic acid obtained by Lactobacillus arabinosus assay after double 

 enzyme treatment. There is very little free pantothenic acid present in 

 fresh tissues.^* Practically all pantothenic acid was found to be bound as 

 CoA. This may be seen from the close correspondence of the amounts of 

 pantothenic acid determined directly by microbial assay and calculated 

 from CoA assay by multiplying with the pantothenic acid factor of 0.7 7 

 per unit of CoA. It appears, therefore, unlikely that there is another panto- 

 thenic acid-containing coenzyme in animal tissue. 



It is noteworthy that the adrenal gland is next highest to liver in CoA 

 content. The well-known relationship between pantothenic acid and adrenal 

 cortex" • ^^ is further emphasized by the decline of CoA in adrenal gland in 

 pantothenic acid deficiency,^* as shown in Fig. 6. A similar depletion of 

 CoA in pantothenic acid deficiency in other organs is shown in the same 

 figure for liver, heart, and kidney. With Lactobacillus arabinosus, the 

 depletion of CoA in a pantothenic acid-deficient organism is shown in 

 Table IV.^" It is compared with an increase in coenzyme of the same or- 

 ganism after incubation with pantothenic acid. Very large amounts of CoA 

 are present in microorganisms carrying out 4-carbon fermentations. Clo- 

 stridium butylicum contains 1000 units per gram dry weight. Clostridium 

 kluyveri contains 500 units per gram. Some examples of the CoA content 

 in plants are shown in Table V. 



It was to a large extent the early recognized presence of CoA in all 

 living matter which made us expect that this coenzyme had to fulfill im- 

 portant functions in intermediary metabolism. 



" A. F. Morgan, Vitamins and Hormones. 9, 162 (1951). 



«8 E. P. Ralli, Trans. 1st Conf. on Adrenal Cortex, New York, p. 159 (1949). 



" R. E. Olson and N. O. Kaplan, J. Biol. Chem. 175, 515 (1948). 



«« G. D. Novell! and F. Lipmann, Arch. Biochem. 14, 23 (1947). 



