Initial Velocity Studies of the Reverse Citrate Cleavage Reaction

The coupling system of hexokinase and glucose 6-phosphate dehydrogenase was used for the initial velocity studies of rat liver citrate cleavage enzyme (EC 4.1.3.8) in the reverse direction. Since the equilibrium constant is concentration-dependent, only portions of the entire initial velocity array...

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Bibliographic Details
Published in:The Journal of biological chemistry 1971-06, Vol.246 (12), p.3777-3782
Main Authors: Farrar, Young Jo K., Plowman, K.M.
Format: Article
Language:English
Subjects:
Acetates
Adenosine Triphosphate
Animals
Citrates
Coenzyme A
Glucosephosphate Dehydrogenase
Hexokinase
Kinetics
Liver - enzymology
Lyases
Magnesium
Male
Mathematics
Models, Biological
NADP
Oxaloacetates
Rats
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Summary:The coupling system of hexokinase and glucose 6-phosphate dehydrogenase was used for the initial velocity studies of rat liver citrate cleavage enzyme (EC 4.1.3.8) in the reverse direction. Since the equilibrium constant is concentration-dependent, only portions of the entire initial velocity array could be examined. The initial velocity studies showed that the reaction mechanism appears sequential. These data are consistent with the following four mechanisms: A, B, C, D ordered; D, C, B, Aordered; A and B ordered, C and D rapid equilibrium random; and D and C ordered, B and A rapid equilibrium random, in which A,B,C, and D are acetyl-CoA, MgADP, oxaloacetate, and phosphate, respectively. Apparent Michaelis constants are presented for the four substrates under various conditions.
ISSN:0021-9258
1083-351X
DOI:10.1016/S0021-9258(18)62101-5