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Effect of glucose‐6‐P on the catalytic and structural properties of glycogen phosphorylase a
Author(s) -
Melpidou Angeliki E.,
Oikonomakos Nikolaos G.
Publication year - 1983
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(83)80884-9
Subject(s) - glycogen phosphorylase , chemistry , enzyme , glycerol , biochemistry , glycogen , substrate (aquarium) , glycogen synthase , glycogen branching enzyme , biology , ecology
Kinetic studies of muscle phosphorylase a in cationic buffer (pH 6.8) demonstrate that glucose‐6‐P competitively inhibits the binding of the substrate, glucose‐1‐P, to the enzyme. The inhibitory effect of glucose‐6‐P is largely overcome by glycerol‐2‐P. AMP counteracts inhibition of the enzyme by glucose‐6‐P, while glucose and glucose‐6‐P can interact to produce a synergistic inhibition of phosphorylase a activity. Preincubation of phosphorylase a with glucose‐6‐P at 20°C results in ∼3‐fold increase in activity, while ultracentrifugation experiments carried out under the same conditions showed that phosphorylase a can be converted to dimers by glucose‐6‐P.