Isocitrate dehydrogenase catalysis

Phosphorylation of an enzyme can affect catalysis in another way by altering substrate-binding affinity. For example, when isocitrate dehydrogenase (an enzyme of the citric acid cycle Chapter 16) is phospho-rylated, electrostatic repulsion by the phosphoryl group inhibits the binding of citrate (a tricarboxylic acid) at the active site. 

JR Cupp, L McAlister-Henn. Kinetic analysis of NAD+-isocitrate dehydrogenase with altered isocitrate binding site contribution of IDH1 and IDH2 subunits to regulation and catalysis. Biochemistry 32 9323-9328, 1993. 

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