3aat
From Proteopedia
ACTIVITY AND STRUCTURE OF THE ACTIVE-SITE MUTANTS R386Y AND R386F OF ESCHERICHIA COLI ASPARTATE AMINOTRANSFERASE
Overview
Arginine-386, the active-site residue of Escherichia coli aspartate aminotransferase (EC 2.6.1.1) 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.
About this Structure
3AAT is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
Reference
Activity and structure of the active-site mutants R386Y and R386F of Escherichia coli aspartate aminotransferase., Danishefsky AT, Onnufer JJ, Petsko GA, Ringe D, Biochemistry. 1991 Feb 19;30(7):1980-5. PMID:1993208 Page seeded by OCA on Sun May 4 20:18:55 2008
