Equilibrium constant glutamate dehydrogenases

Only one single concentration term present, and another Michaelis constant equal to zero (B, C, A bAC terms missing). This is an ordered mechanism with addition of A in steady state and B in rapid equilibrium, and examples include glutamate dehydrogenase with a-ketovalerate or a-ketobutyrate as substrates (14). 

Little is known about the NADH aitd NAD content of the cytosol. In order to estimate the NADH/NAD ratio, the cytosolic contents of malate, aspartate, glutamate and 2-oxoglutarate were determined by nonaqueous fractionation of spinach leaves (Table l). From these values the NADH/NAD ratio was calculated on the reasonable assumption that the reactions catalyzed by the cytosolic malate dehydrogenase and glutamate oxaloacetate transaminase are near to equilibrium. Introducing the equilibrium constants of these enzymes 2.8. 10 at pH 7.0 (4), Kqqt... 

With crystalline glutamic acid dehydrogenase the turnover numbers (moles of DPN reduced or of DPNH oxidized per minute per 100,000 g. of enzyme at 25°C.) were 290 and 3000 respectively. Chance and Smith have reported the following unpublished information about the crystalline enzyme of Olson and Anfinsen. The Km values for DPN and DPN.2H are of the same order (10 M) as those for glutamate and a-ketoglutarate (10 M). The equilibrium constant for the reaction... 

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