The stimulation of liver phosphorylase b by AMP, fluoride and sulfate. A technical note on the specific determination of the a and b forms of liver glycogen phosphorylase.
1. The activity of liver phosphorylase b from several mammalian species has been studied. The enzyme from rat or mouse has a higher activity than the rabbit enzyme, which is itself more active than pig liver phosphorylase b. 2 The activity of liver phosphorylase b is influenced by anions and by AMP, and these effects are influenced by pH. Fluoride, which is currently added to the assay mixture of phosphorylase a in crude preparations, is about as active as sulfate as a stimulator of phosphorylase b. 3. When assayed at pH 6.1 and in the presence of 0.15 M NaF, the activity of rat liver phosphorylase b reaches 25% of that of the a enzyme; if 1 mM AMP is also present, this value rises to 50%. 4. Methods are described that allow the determination of liver phosphorylase a without interference of b, and the determination of total phosphorylase (a+b) in rat liver.
D000249:Adenosine Monophosphate / Q000494:pharmacology*; D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D005459:Fluorides / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D051379:Mice; D006005:Phosphorylases / Q000378:metabolism*; D011817:Rabbits; D051381:Rats; D013045:Species Specificity; D013431:Sulfates / Q000494:pharmacology*
D013431:Sulfates; D002110:Caffeine; D000249:Adenosine Monophosphate; D006005:Phosphorylases; D005459:Fluorides