602 



PANTOTHENIC ACID 



CoA 



10 15 20 



UNITS ADDED 



25 



Fig. 3. Proportionality of arsenolysis with coenzyme A concentration. The acetyl 

 phosphate values represent micromoles of acetyl phosphate decomposed in 15 min- 

 utes. Coenzyme A values are recorded in units per milliliter. Conditions: 0.05 M 

 potassium arsenate; 0.1 tris(hydroxymethyl)aminomethane (pH 8.0); 22 /iM. acetyl 

 phosphate; 0.01 M cysteine; 0.002 M MgCh ; 0.5 mg. of enzyme (from Lot L); am- 

 monium sulfate fraction, between 70 and 90% saturation. Final volume 1 ml. (Drawn 

 from Table IV in Stadtman et al.^^") 



degradation. This procedure has been useful in the study of the structure, 

 in particular, in conjunction with assay procedures more specific for intact 

 CoA. As such, the arsenolysis assay^' has been very important. 



In many microorganisms, in particular, in Clostridium kluyveri, an 

 enzyme, transacetylase,^^' ^° is present which equilibrates acetyl phosphate 

 and CoA to acetyl-CoA and phosphate. If arsenate is added to this system, 

 it equilibrates with arsenate, yielding acetyl arsenate, which decomposes 

 immediately .2" The arsenolysis of acetyl phosphate is CoA-dependent and 

 may be measured easily by following acetyl phosphate decomposition 

 with the hydroxamic acid reaction.^* CoA can be removed from microbial 

 extracts by shaking with Dowex-1 chloride.^*- ^^ The Dowex-treated apo- 

 enzyme may be used for CoA assay. Over a wide range, the rate of acetyl 

 phosphate disappearance is proportional with CoA concentration, as shown 



19 E. R. Stadtman, G. D. Novelli, and F. Lipmann, /. Biol. Chem. 191, 365 (1951) 



20 E. R. Stadtman and H. A. Barker, /. Biol. Chem. 184, 769 (1950). 

 " H. Chantrenne and F. Lipmann, J. Biol. Chem. 187, 757 (1950). 



"<• E. R. Stadtman, M. Doudoroff, and F. Lipmann, /. Biol. Chem. 191, 377 (1951). 



