Isotopic exchange, malate dehydrogenase

The formation of abortive complexes of the type EAQ and EPB, a common cause of substrate inhibition of dehydrogenases (Section II, F), can also be detected in isotope exchange experiments by inhibition of all exchanges when the concentrations of A and Q or P and B are increased together. The complexes E NADH malate (34) and E NAD(P)H glutamate (44), for example, were detected in this way, and are probably responsible for the substrate inhibition observed in initial rate studies of these enzymes (Section II,F,1). The latter complex, but not the former. 

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