616 PANTOTHENIC ACID 



TABLE IV^o 



Coenzyme Synthesis in L. arabinosus 



(Pantothenic acid was determined microbiologically. Coenzyme was determined 



enzymatically.) 



" This value is calculated by multiplying the number of coenzyme units with the constant factor of 0.7 

 T of pantothenic acid per unit of coenzyme. 



^ Bound pantothenic acid is determined after liberation through incubation with a mixture of acetone 

 pigeon liver extract and intestinal phosphatase. This enzyme mixture was shown to liberate pantothenic acid 

 from coenzyme A. Intact coenzyme does not test as pantothenic acid microbiologically. 



" Too little to be determined accurately. 



TABLE V" 

 Coenzyme A in Plant Material 



Units per gram fresh weight 



Spinach 0.74 



Tomato 1,3 



Frozen peas 4.5 



Wheat germ (commercial sample) 30 



Royal jelly (bee) 



CoA-requiring reactions into two distinct classes, namely, acetyl donor 

 and acetyl acceptor enzyme systems.®^ Particularly useful for the identifi- 

 cation of partial reactions in acetyl transfer was the separation of the 

 various donor and acceptor enzymes present in pigeon liver extract by 

 Chou in our laboratory. Very important, furthermore, was the recognition 

 of an activating system in bacterial extract for acetyl phosphate to act as 

 an acetyl donor. ^'' ^^ This enzymatic process of activation was identified 

 with the transacetylase reaction of Stadtman and Barker.^*- ^° This re- 

 action has been described in a previous paragraph as an assay system for 

 intact CoA. The CoA dependence of the phosphate exchange of acetyl- 

 bound and inorganic phosphate, as well as of the arsenolysis of acetyl 



«6 M. Soodak and F. Lipmann, J. Biol. Chem. 175, 999 (1948). 

 " T. C. Chou and F. Lipmann, /. Biol. Chem. 196, 89 (1952). 



