Altering the Substrate Specificity of Glutamate Dehydrogenase from Bacillus subtilis by Site-Directed Mutagenesis

Abstract

The Lys80, Gly82 and Met101 residues of glutamate dehydrogenase from Bacillus subtilis were mutated into a series of single mutants. The wild-type enzyme was highly specific for 2-oxoglutarate, whereas G82K and M101S dramatically switched to increased specificity for oxaloacetate with k_cat values 3.45 and 5.68 s⁻¹, which were 265-fold and 473-fold higher respectively than those for 2-oxoglutarate.