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Glyceraldehyde-3-Phosphate Dehydrogenase [and Discussion]
K. Dalziel, N. V. McFerran, A. J. Wonacott and T. Keleti
Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
Vol. 293, No. 1063, The Enzymes of Glycolysis: Structure, Activity and Evolution (Jun. 26, 1981), pp. 105-118
Published by: Royal Society
Stable URL: http://www.jstor.org/stable/2395661
Page Count: 14
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Conflicting experimental evidence of the pathway of catalysis for the enzyme from rabbit, pig and lobster muscle tissues is reviewed. Transient kinetic studies with the enzyme from rabbit muscle are presented. The results are shown to be consistent with the double-displacement mechanism of catalysis originally proposed by Segal & Boyer (1953). The rate constant for combination of the aldehyde form of the substrate with the NAD+ complex of the enzyme is about 3 × 107 M-1 S-1, and for all four subunits of the molecule the rate constant for hydride transfer in the ternary complex formea is greater than 103 S-1, consistent with their simultaneous participation in catalysis. Recent steady-state kinetic studies with the rabbit muscle enzyme, in contrast to earlier studies, also provide evidence to support the Segal-Boyer pathway if the kinetic effects of the negative cooperativity of NAD+ binding are taken into account. Experimental data for the binding of NAD+ to the enzyme from muscles and from Bacillus stearothermophilus, and their interpretations, are also briefly reviewed. The information currently available from X-ray crystallography regarding the structures of holoenzyme and apoenzyme from B. stearothermophilus and lobster muscle is outlined.
Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences © 1981 Royal Society