1IB6

CRYSTAL STRUCTURE OF R153C E. COLI MALATE DEHYDROGENASE

1IB6 の概要

• エントリーDOI: 10.2210/pdb1ib6/pdb
• 分子名称: MALATE DEHYDROGENASE, SULFATE ION, NICOTINAMIDE-ADENINE-DINUCLEOTIDE, ... (4 entities in total)
• 機能のキーワード: oxidoreductase, dehydrogenase, malate dehydrogenase, substrate specificity
• 由来する生物種: Escherichia coli
• タンパク質・核酸の鎖数: 4
• 化学式量合計: 131819.22

構造登録者

Bell, J.K.,Yennawar, H.P.,Wright, S.K.,Thompson, J.R.,Viola, R.E.,Banaszak, L.J. (登録日: 2001-03-27, 公開日: 2001-09-19, 最終更新日: 2024-02-07)

主引用文献

Bell, J.K.,Yennawar, H.P.,Wright, S.K.,Thompson, J.R.,Viola, R.E.,Banaszak, L.J.
Structural Analyses of a Malate Dehydrogenase with a Variable Active Site
J.Biol.Chem., 276:31156-31162, 2001

PubMed Abstract: Malate dehydrogenase specifically oxidizes malate to oxaloacetate. The specificity arises from three arginines in the active site pocket that coordinate the carboxyl groups of the substrate and stabilize the newly forming hydroxyl/keto group during catalysis. Here, the role of Arg-153 in distinguishing substrate specificity is examined by the mutant R153C. The x-ray structure of the NAD binary complex at 2.1 A reveals two sulfate ions bound in the closed form of the active site. The sulfate that occupies the substrate binding site has been translated approximately 2 A toward the opening of the active site cavity. Its new location suggests that the low catalytic turnover observed in the R153C mutant may be due to misalignment of the hydroxyl or ketone group of the substrate with the appropriate catalytic residues. In the NAD.pyruvate ternary complex, the monocarboxylic inhibitor is bound in the open conformation of the active site. The pyruvate is coordinated not by the active site arginines, but through weak hydrogen bonds to the amide backbone. Energy minimized molecular models of unnatural analogues of R153C (Wright, S. K., and Viola, R. E. (2001) J. Biol. Chem. 276, 31151-31155) reveal that the regenerated amino and amido side chains can form favorable hydrogen-bonding interactions with the substrate, although a return to native enzymatic activity is not observed. The low activity of the modified R153C enzymes suggests that precise positioning of the guanidino side chain is essential for optimal orientation of the substrate.

PubMed: 11389141
DOI: 10.1074/jbc.M100902200

実験手法

X-RAY DIFFRACTION (2.1 Å)