1AJR

REFINEMENT AND COMPARISON OF THE CRYSTAL STRUCTURES OF PIG CYTOSOLIC ASPARTATE AMINOTRANSFERASE AND ITS COMPLEX WITH 2-METHYLASPARTATE

1AJR の概要

• エントリーDOI: 10.2210/pdb1ajr/pdb
• 分子名称: ASPARTATE AMINOTRANSFERASE (2 entities in total)
• 機能のキーワード: cytosolic aspartate aminotransferase, pig, homodimer in the absence of ligand, aminotransferase
• 由来する生物種: Sus scrofa (pig)
• 細胞内の位置: Cytoplasm: P00503
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 93243.28

構造登録者

Rhee, S.,Silva, M.M.,Hyde, C.C.,Rogers, P.H.,Metzler, C.M.,Metzler, D.E.,Arnone, A. (登録日: 1997-05-08, 公開日: 1997-08-20, 最終更新日: 2024-06-05)

主引用文献

Rhee, S.,Silva, M.M.,Hyde, C.C.,Rogers, P.H.,Metzler, C.M.,Metzler, D.E.,Arnone, A.
Refinement and comparisons of the crystal structures of pig cytosolic aspartate aminotransferase and its complex with 2-methylaspartate.
J.Biol.Chem., 272:17293-17302, 1997

PubMed Abstract: Two high resolution crystal structures of cytosolic aspartate aminotransferase from pig heart provide additional insights into the stereochemical mechanism for ligand-induced conformational changes in this enzyme. Structures of the homodimeric native structure and its complex with the substrate analog 2-methylaspartate have been refined, respectively, with 1.74-A x-ray diffraction data to an R value of 0.170, and with 1.6-A data to an R value of 0.173. In the presence of 2-methylaspartate, one of the subunits (subunit 1) shows a ligand-induced conformational change that involves a large movement of the small domain (residues 12-49 and 327-412) to produce a "closed" conformation. No such transition is observed in the other subunit (subunit 2), because crystal lattice contacts lock it in an "open" conformation like that adopted by subunit 1 in the absence of substrate. By comparing the open and closed forms of cAspAT, we propose a stereochemical mechanism for the open-to-closed transition that involves the electrostatic neutralization of two active site arginine residues by the negative charges of the incoming substrate, a large change in the backbone (phi,psi) conformational angles of two key glycine residues, and the entropy-driven burial of a stretch of hydrophobic residues on the N-terminal helix. The calculated free energy for the burial of this "hydrophobic plug" appears to be sufficient to serve as the driving force for domain closure.

PubMed: 9211866
DOI: 10.1074/jbc.272.28.17293

実験手法

X-RAY DIFFRACTION (1.74 Å)