3AAT image
Entry Detail
PDB ID:
3AAT
Title:
ACTIVITY AND STRUCTURE OF THE ACTIVE-SITE MUTANTS R386Y AND R386F OF ESCHERICHIA COLI ASPARTATE AMINOTRANSFERASE
Biological Source:
Source Organism:
Host Organism:
PDB Version:
Deposition Date:
1990-12-06
Release Date:
1992-01-15
Method Details:
Experimental Method:
Resolution:
2.80 Å
R-Value Observed:
0.21
Space Group:
C 2 2 21
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:ASPARTATE AMINOTRANSFERASE
Mutations:R374F
Chain IDs:A
Chain Length:396
Number of Molecules:1
Biological Source:Escherichia coli
Primary Citation
Activity and structure of the active-site mutants R386Y and R386F of Escherichia coli aspartate aminotransferase.
Biochemistry 30 1980 1985 (1991)
PMID: 1993208 DOI: 10.1021/bi00221a035

Abstact

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.

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