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Phillips W. Robbins and Fritz Lipmann 



strongly marked in the absence of CoA, indicating a prevalence of 

 glycolytic breakdown in the latter case. We were rather interested 

 in the radioactive spot below the lactic acid which appears strongly 

 in the CoA-containing sample, until it was identified as phospho- 

 glycerol. The appearance of this compound under these conditions 

 may be of interest but we did not wish to expand on this observation. 

 When we came to test insulin in this system, it proved to be 



5 10 15 20 



Coenzyme A - units/ml. 



25 



Fig. 2. Effect of CoA concentration on glucose incorporation into 

 glycogen and on the maintenance of glycogen. Incubations were 

 carried out for 60 minutes as described by Robbins, Traut and 

 Lipmann (1959) and in Fig. 1. The reactions were stopped by 

 adding an equal volume of 60 per cent KOH. Glycogen was isolated 

 for counting and for chemical glycogen determinations essentially 

 by the method described by Hassid and Abraham (1957). 



completely inactive. Adrenaline, at a relatively high concentration, 

 inhibits glucose incorporation into glycogen. 



We come now to the results which have impressed us most, and 

 which bear on the relationship bet^\ 3n phosphorylase and glycogen 

 synthesis. The experiment traced in Fig. 4 was carried out to 

 explore the effect that an increase in phosphorylase a by addition of 

 phosphorylase kinase might have on glycogen synthesis. It appears 

 that an addition of kinase which maintains phosphorylase a at a 

 higher level, almost completely abolishes glucose incorporation. In 

 contrast, in the absence of kinase, the steady decrease in phos- 

 phorylase activity to practically zero coincides rather startlingly 

 with an increase of glucose incorporation into glycogen. In Fig. 5, 



