Frog liver glycogen synthase. In vitro and in vivo interconversions between I and D forms. |
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| Authors: | M J Casti?eiras A Boronat E Itarte J J Guinovart M R Pérez |
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| Affiliation: | Department of Biochemistry, University of Barcelona, School of Pharmacy, Spain. |
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| Abstract: | 1. Frog liver has enzymatic systems able to interconvert glycogen synthase. 2. D to I conversion is achieved in vitro by incubation at 30 degrees C. ATP, ADP, inorganic phosphate and glycogen are inhibitors of this conversion, whereas glucose-6-P and Mg2+ stimulate it. 3. I to D conversion in vitro depends on ATP-Mg2+. Cyclic-AMP activates this conversion, while glucose-6-P inhibits it. 4. Injection of glucose, ribose, mannose, fructose, galactose, and cortisone into frogs increase liver percentage of I activity. 5. Glucagon and adrenaline decrease percentage of I activity. |
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