Isoenzymes Phosphorylases Plants phosphorylase Kinetics Molecular Weight Support, Non-U.S. Gov't article enzymology isoenzyme isolation and purification metabolism molecular weight plant CARBON Carbon Radioisotopes Centrifugation, Density Gradient Chromatography, Affinity Electrophoresis, Polyacrylamide Gel Glucans Glucosephosphates Glycoproteins Heat Substrate Specificity affinity chromatography carbon density gradient centrifugation enzyme specificity glucan glucose 1 phosphate