Activity and structure of the active-site mutants R386Y and R386F of Escherichia coli aspartate aminotransferase.Danishefsky, A.T., Onnufer, J.J., Petsko, G.A., Ringe, D.
(1991) Biochemistry 30: 1980-1985
- PubMed: 1993208
- PubMed Abstract:
- Preliminary X-Ray Data for Aspartate Aminotransferase from Escherichia Coli
Smith, D.L.,Ringe, D.,Finlayson, W.L.,Kirsch, J.F.
(1986) J.Mol.Biol. 191: 301
- 2.8-Angstroms-Resolution Crystal Structure of an Active-Site Mutant of Aspartate Aminotransferse from Escherichia Coli
Smith, D.L.,Almo, S.C.,Toney, M.D.,Ringe, D.
(1989) Biochemistry 28: 8161
Arginine-386, the active-site residue of Escherichia coli aspartate aminotransferase (EC 184.108.40.206) that binds the substrate alpha-carboxylate, was replaced with tyrosine and phenylalanine by site-directed mutagenesis. This experiment was undertaken to ...
Arginine-386, the active-site residue of Escherichia coli aspartate aminotransferase (EC 220.127.116.11) that binds the substrate alpha-carboxylate, was replaced with tyrosine and phenylalanine by site-directed mutagenesis. This experiment was undertaken to elucidate the roles of particular enzyme-substrate interactions in triggering the substrate-induced conformational change in the enzyme. The activity and crystal structure of the resulting mutants were examined. The apparent second-order rate constants of both of these mutants are reduced by more than 5 orders of magnitude as compared to that of wild-type enzyme, though R386Y is slightly more active than R386F. The 2.5-A resolution structure of R386F in its native state was determined by using difference Fourier methods. The overall structure is very similar to that of the wild-type enzyme in the open conformation. The position of the Phe-386 side chain, however, appears to shift with respect to that of Arg-386 in the wild-type enzyme and to form new contacts with neighboring residues.
Department of Chemistry, Massachusetts Institute of Technology, Cambridge 02139.