2QKC

Structural and Kinetic Study of the Differences between Human and E.coli Manganese Superoxide Dismutases

2QKC の概要

• エントリーDOI: 10.2210/pdb2qkc/pdb
• 関連するPDBエントリー: 2QKA
• 分子名称: Superoxide dismutase [Mn], MANGANESE (II) ION (3 entities in total)
• 機能のキーワード: metalloenzyme, proton wire, acetylation, manganese, metal-binding, mitochondrion, oxidoreductase, polymorphism, transit peptide
• 由来する生物種: Homo sapiens (human)
• 細胞内の位置: Mitochondrion matrix: P04179
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 43991.34

構造登録者

Zheng, J.,Domsic, J.F.,Cabelli, D.,McKenna, R.,Silverman, D.N. (登録日: 2007-07-10, 公開日: 2008-07-29, 最終更新日: 2023-08-30)

主引用文献

Zheng, J.,Domsic, J.F.,Cabelli, D.,McKenna, R.,Silverman, D.N.
Structural and kinetic study of differences between human and Escherichia coli manganese superoxide dismutases.
Biochemistry, 46:14830-14837, 2007

PubMed Abstract: Human manganese superoxide dismutase (MnSOD) is characterized by a product inhibition stronger than that observed in bacterial forms of MnSOD. Previous studies show that the conserved, active-site residue Tyr34 mediates product inhibition; however, the protein environment of Tyr34 is different in human and Escherichia coli MnSOD. We have prepared two site-specific mutants of human MnSOD with replacements of Phe66 with Ala and Leu (F66A and F66L, respectively), altering the surroundings of Tyr34. Pulse radiolysis was used to generate superoxide, and measurements of catalysis were taken in single-turnover experiments by observing the visible absorbance of species of MnSOD and under catalytic conditions observing the absorbance of superoxide. The mutation of Phe66 to Leu resulted in a mutant of human MnSOD with weakened product inhibition resembling that of E. coli MnSOD. Moreover, the mechanism of this weakened product inhibition was similar to that in E. coli MnSOD, specifically a decrease in the rate constant for the oxidative addition of superoxide to Mn2+MnSOD leading to the formation of the peroxide-inhibited enzyme. In addition, the crystal structures of both mutants have been determined and compared to those of wild-type human and E. coli MnSOD. The crystallographic data suggest that the solvent structure and its mobility as well as side chain conformations may affect the extent of product inhibition. These data emphasize the role of residue 66 in catalysis and inhibition and provide a structural explanation for differences in catalytic properties between human and certain bacterial forms of MnSOD.

PubMed: 18044968
DOI: 10.1021/bi7014103

実験手法

X-RAY DIFFRACTION (2.3 Å)