180 A SYMPOSIUM ON RESPIRATORY ENZYMES 



Table 2.— Position of equilibria at pH 7 and 25° 



Glycogen + inorganic phosphate (77 per cent)<=^gIucose-l-phosphate (23 per cent) (1) 

 Glucose-1-phosphate (6 per cent) i=^glucose-6-phosphate (94 per cent) (2) 



Glucose-6-phosphate (70 per cent)<=^fructose-6-phosphate (30 per cent) (3) 



1-phosphate is formed. The overall reaction cannot progress very 

 far to the glycogen side, but when barium ions are added, which 

 cause precipitation of the inorganic phosphate set free when re- 

 action 1 goes to the left, up to 40 per cent of added glucose-6- 

 phosphate can be converted to glycogen. Such an experiment is 

 shown in Table 3. 



Table 3.— Glycogen formation from barium salt of glucose-6- 

 phosphate with dialyzed muscle extract 



(Extract + Mg++ ions + catalytic amounts of glycogen and adenylic acid. 

 Incubated at 30° C.) 



Muscle extract, prepared in the usual manner and dialyzed free 

 of inorganic phosphate, shows only a slight activity when the barium 

 salt of glucose-6-phosphate is added. When the same extract was 

 concentrated sevenfold by freezing and by drying in vacuo, the 

 activity was markedly increased, since up to 33 per cent of the 

 added glucose-6-phosphate was converted to glycogen. The glycogen 

 formation was measured by (1) the amount of inorganic phosphate 

 set free, which precipitates as the barium salt because of the addition 

 of barium ions; (2) the increase in glycogen, which is somewhat less 

 than the increase calculated from the inorganic phosphate because 

 of the presence of diastase in the extract; and (3) the color reaction 

 with iodine, which is blue for the polysaccharide formed by muscle 

 phosphorylase. As a control procedure, the addition of adenylic 

 acid and of the glycogen necessary for the priming of the reaction 



