Purification of phosphorylase B and some properties of phosphorylase A and B from liver of the flounder ( Platichtys flesus L.)

Abstract

1. 1. Flounder liver phosphorylase b has been obtained in homogeneous form. The molecular weight estimated by sucrose gradient centrifugation was 182,000. 2. 2. Conversion of phosphorylase b to phosphorylase a resulted in the incorporation of 2 mol phosphate per mol phosphorylase b. 3. 3. Optimum activity is obtained at pH 6.5 for both forms. 4. 4. Both phosphorylase a and phosphorylase b are activated in the presence of AMP, NaF and Na 2SO 4. 5. 5. Phosphorylase b activity measured as a function of the glucose-1-P concentration shows positive cooperatively in the absence and the presence of AMP. Phosphorylase a shows positive cooperativity in the absence of AMP, and Michaelis-Menten kinetics in the presence of AMP, when measured as a function of the glucose-1-P concentration. 6. 6. Phosphorylase b shows Michaelis-Menten kinetics when measured as a function of the glycogen concentration.