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Competitive Inhibition of Rat Brain Hexokinase by 2‐Deoxyglucose, Glucosamine, and Metrizamide
Author(s) -
Bertoni John M.
Publication year - 1981
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1981.tb06322.x
Subject(s) - metrizamide , hexokinase , deoxyglucose , biochemistry , glucosamine , metabolism , chemistry , biology , endocrinology , glycolysis , spinal cord , neuroscience , myelography
The effects of metrizamide on the kinetics of rat brain hexokinase were compared in vitro with those of 2‐deoxyglucose and glucosamine. Although metrizamide, 2‐deoxyglucose, and glucosamine are known to be competitive inhibitors of approximately equal potency for glucose of yeast hexokinase ( K 1 approximately 0.7 m m for all three), metrizamide is a much weaker competitive inhibitor ( K i about 20 m m ) of rat brain hexokinase than either 2‐deoxyglucose or glucosamine ( K i about 0.3 m m for both). This indicates a greater active site specificity of rat brain hexokinase than of yeast hexokinase. Rat brain hexokinase activity is enhanced approximately threefold in the presence of 0.05, 0.2, and 0.8 mg/ml bovine serum albumin, while yeast hexokinase is only enhanced by 50% under these conditions. Despite the high K i value for metrizamide, interference with glucose metabolism may occur whenever metrizamide is present in much higher concentrations than glucose. Myelography in humans is one such situation.