Regulation of locust fat-body phosphorylase.
1. Glycogen phosphorylase of locust fat-body was partially purified by differential centrifugation and dissociation from glycogen particles at two pH values. 2. Optimum activity was obtained at pH6.6-6.7. 3. The calculated apparent K(m) values for glycogen and glucose 1-phosphate were 0.08% and 10-13mm respectively. 4. 5'-AMP activated in the range 5mum-1mm. 5. Glucose 6-phosphate is a competitive inhibitor for the substrate glucose 1-phosphate (K(i)=1.7mm). 5'-AMP abolishes this inhibition. Glucose weakly inhibits (K(i)=25-30mm), but trehalose does not inhibit even at 100mm. 6. It is suggested that glucose 6-phosphate is a major regulator of glycogen phosphorylase activity in locust fat-body.
D000249:Adenosine Monophosphate; D000818:Animals; D005958:Glucosephosphates; D006003:Glycogen; D006110:Grasshoppers / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D006005:Phosphorylases / Q000037:antagonists & inhibitors; D013696:Temperature
D005958:Glucosephosphates; D000249:Adenosine Monophosphate; D006003:Glycogen; D006005:Phosphorylases