3daa

From Proteopedia

CRYSTALLOGRAPHIC STRUCTURE OF D-AMINO ACID AMINOTRANSFERASE INACTIVATED BY PYRIDOXYL-D-ALANINE

Overview

The three-dimensional structures of two forms of the D-amino acid, aminotransferase (D-aAT) from Bacillus sp. YM-1 have been determined, crystallographically: the pyridoxal phosphate (PLP) form and a complex, with the reduced analogue of the external aldimine, N-(5'-phosphopyridoxyl)-d-alanine (PPDA). Together with the previously, reported pyridoxamine phosphate form of the enzyme [Sugio et al. (1995), Biochemistry 34, 9661], these structures allow us to describe the pathway, of the enzymatic reaction in structural terms. A major determinant of the, enzyme's stereospecificity for D-amino acids is a group of three residues, (Tyr30, Arg98, and His100, with the latter two contributed by the, neighboring subunit) forming four hydrogen bonds to the substrate, alpha-carboxyl group. The replacement by hydrophobic groups of the, homologous residues of the branched chain L-amino acid aminotransferase, (which has a similar fold) could explain its opposite stereospecificity., As in L-aspartate aminotransferase (L-AspAT), the cofactor in D-aAT tilts, (around its phosphate group and N1 as pivots) away from the catalytic, lysine 145 and the protein face in the course of the reaction. Unlike, L-AspAT, D-aAT shows no other significant conformational changes during, the reaction.

About this Structure

3DAA is a Single protein structure of sequence from Bacillus sp. with as ligand. Active as D-amino-acid transaminase, with EC number 2.6.1.21 Known structural/functional Sites: and . Full crystallographic information is available from OCA.

Reference

Crystallographic study of steps along the reaction pathway of D-amino acid aminotransferase., Peisach D, Chipman DM, Van Ophem PW, Manning JM, Ringe D, Biochemistry. 1998 Apr 7;37(14):4958-67. PMID:9538014

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