Insights into enzyme function from studies on mutants of dihydrofolate reductase

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Science  04 Mar 1988:
Vol. 239, Issue 4844, pp. 1105-1110
DOI: 10.1126/science.3125607


Kinetic analysis and protein mutagenesis allow the importance of individual amino acids in ligand binding and catalysis to be assessed. A kinetic analysis has shown that the reaction catalyzed by dihydrofolate reductase is optimized with respect to product flux, which in turn is predetermined by the active-site hydrophobic surface. Protein mutagenesis has revealed that specific hydrophobic residues contribute 2 to 5 kilocalories per mole to ligand binding and catalysis. The extent to which perturbations within this active-site ensemble may affect catalysis is discussed in terms of the constraints imposed by the energy surface for the reaction.