Mechanism of Glycogen Synthesis in Muscle 189 



picture with and without CoA, which has some bearing on the theme 

 of this symposium, is illustrated by Fig. 3, a radioautograph of an 

 electropherogram. Samples were taken at the end of the experiment 



^ 



15 



30 45 



60 75 



Min-utes 



Fig. 1. Oxygen uptake by pigeon breast 

 muscle preparations in the presence and 

 absence of CoA. Experiments were carried 

 out essentially as described by Robbins, Traut 

 and Lipmann (1959). The Warburg flasks 

 contained 1 • 2 ml. of a 1 : 4 homogenate of 

 pigeon breast muscle. The final volume was 

 2 ml. and contained 4 (imoles of ^^C-glucose (2 

 [jLC) in addition to the homogenate. CoA was 

 present at a concentration of 10 units/ml. 



represented in Fig. 1. It may be seen on the radioautograph that 

 without added CoA, glycogen is practically unmarked, while with 

 maintenance of respiration by CoA it picks up a good deal of radio- 

 activity. In contrast, the radioactive lactic acid, obviously formed 

 from radioactive glucose, is weak in the presence of and rather 



