title: The importance of arginine 102 for the substrate specificity of Escherichia coli malate dehydrogenase.
abstract: The malate dehydrogenase from Escherichia coli has been specifically altered at a single amino acid residue by using site-directed mutagenesis. The conserved Arg residue at amino acid position 102 in the putative substrate binding site was replaced with a Gln residue. The result was the loss of the high degree of specificity for oxaloacetate. The difference in relative binding energy for oxaloacetate amounted to about 7 kcal/mol and a difference in specificity between oxaloacetate and pyruvate of 8 orders of magnitude between the wild-type and mutant enzymes. These differences may be explained by the large hydration potential of Arg and the formation of a salt bridge with a carboxylate group of oxaloacetate.
authors: Division of Biotechnology, PHLS Centre for Applied Microbiology and Research, Porton Down, Salisbury, UK.
authors: D J
authors: DJ
authors: Nicholls
authors: J
authors: J
authors: Miller
authors: M D
authors: MD
authors: Scawen
authors: A R
authors: AR
authors: Clarke
authors: J J
authors: JJ
authors: Holbrook
authors: T
authors: T
authors: Atkinson
authors: C R
authors: CR
authors: Goward
mesh_terms: D000595:Amino Acid Sequence; D001120:Arginine; D001665:Binding Sites; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D005973:Glutamine; D007700:Kinetics; D008291:Malate Dehydrogenase / Q000235:genetics / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding; D013379:Substrate Specificity
chemical_list: D005973:Glutamine; D001120:Arginine; D008291:Malate Dehydrogenase