Some factors influencing the formation of Robison ester from glycogen and inorganic phosphate in muscle extract

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Abstract
Amylases inhibited the formation of Robison ester in muscle extract. The hydrolytic enzyme acted as competitor with the phosphorylating enzyme for the substrate glycogen. Oxidizing agents inhibited Robison ester formation. The agents used were catechol plus catechol oxidase, and SS-glutathione. Small amounts of adrenaline had no effect on Robison ester formation. Such were SH-glutathione, cyanide, thiolacetic acid, denatured protein, sodium hydrosulphite and evacuation. Muscle extract boiled for 2 mins. was still able to phosphorylate glycogen and to form Robison ester. Cu++, Fe+++, Zn++, inhibited Robison ester formation; Ni++ and Co++ increased it. CO++ increased Robison ester formation at optimum Mg++ concentration. Ascorbic acid inhibited Robison ester formation. It acted in concs, of about 1%. Insulin inhibited Robison ester formation but it allowed accumulation of Cori ester to go on. Its action was largely due to the removal of Mg++ from soln. Insulin, the ss groups of which were removed either by cyanide or by muscle extract, did not inhibit Robison ester formation. Data were given regarding the inhibition of phosphorylysis of glycogen by sugars. Of these the most active are glucose and mannose as well as Robison ester. Hexosediphosphate increased phosphoryla-tion of glycogen and consequently the formation of Robison ester. Its effect was not inhibited by iodoacetate and had therefore to be distinguished from the phosphorylation coupled with oxido reduction processes.