Phosphorolysis and synthesis of glycogen in animal tissues

Publisher Website
Google Scholar
Abstract
A modified method for the prepn. of phosphorylase by adsorption on A1(OH)3 was described. By this method, phosphorylase was demonstrated in all animal tissues. The phosphorylase activity and the intensity of the glycogen metabolism of a tissue were shown to be correlated. The same was true also of the phosphorolytic breakdown of glycogen. Subcutaneous tissue possessed a highly active phosphorylase, and metabolized glycogen at a high rate. Phosphorylase was not found in the muscles of rats less than 10 days of age. In 14-day-old rats the enzyme was already comparatively active. Brain tissue from new-born rats showed 60% of the phosphorylase activity of the adult brain. Phosphoglucomutase in new-born rat brain was either inactive or absent. This enzyme was the limiting factor in glycogen phosphorolysis up to 14-20 days after birth, after which time its activity approached that found in the adult brain. In intoxication by P, CC14 and chloroform, liver phosphoglucomutase was inactivated, but phosphorylase activity was almost normal. In adrenalectomized as well as in thyroidectomized rats, no" decrease in glycogen phosphorolysis by muscle was demonstrated. Some properties of the phosphorylase of muscle were studied: on irradiation with u.-v. light, or on heating to 55[degree] for 20 min., complete destruction of the enzyme occurred. Adenylic acid diminished the inhibition caused by glucose in 2% conc. With 0.3% glucose no lessening of inhibition was found when adenylic acid was added. With potato phosphorylase no inhibition of glycogen synthesis by 2% glucose was found. In synthesis by muscle, phosphorylase was slowed down by low temp. or by ageing of the enzyme prepn., an iodine color reaction such as that given by glycogen was observed after 5-10 min. of synthesis.