Thermodynamic analysis of ionizable groups involved in the catalytic mechanism of human matrix metalloproteinase 7 (MMP-7).
スポンサーリンク
概要
- 論文の詳細を見る
Human matrix metalloproteinase 7 (MMP-7) exhibits a broad bell-shaped pH-dependence with the acidic and alkaline pK(e) (pK(e1) and pK(e2)) values of about 4 and 10. In this study, we estimated the ionizable groups involved in its catalytic mechanism by thermodynamic analysis. pK(a) of side chains of L-Asp, L-Glu, L-His, L-Cys, L-Tyr, L-Lys, and L-Arg at 25-45°C were determined by the pH titration of amino-acid solutions, from which their enthalpy changes, ∆H°, of deprotonation were calculated. pK(e1) and pK(e2) of MMP-7 at 15-45°C were determined in the hydrolysis of (7-methoxycoumarin-4-yl)acetyl-L-Pro-L-Leu-Gly-L-Leu-[N(3)-(2,4-dinitrophenyl)-L-2,3-diaminopropionyl]-L-Ala-L-Arg-NH(2), from which ∆H(o) for pK(e1) and pK(e2) was calculated. The ∆H(o) for pK(e1) (-20.6±6.1kJmol(-1)) was similar to that for L-Glu (-23.6±5.8kJmol(-1)), and the ∆H(o) for pK(e2) (89.9±4.0kJmol(-1)) was similar to those for L-Arg (87.6±5.5kJmol(-1)) and L-Lys (70.4±4.4kJmol(-1)). The mutation of the active-site residue Glu198 into Ala completely abolished the activity, suggesting that Glu198 is the ionizable group for pK(e1). On the other hand, no arginine or lysine residues are found in the active site of MMP-7. We proposed a possibility that a protein-bound water is the ionizable group for pK(e2).
論文 | ランダム
- 小惑星イトカワ表面に存在する岩塊の表面組織の解読 : 小惑星のフィールド岩石学の試み(始原天体研究のこれまでとこれから:探査を仲介とした異分野交流)
- 隕石に由来する新しい磁性材料--宇宙からのグリーンイノベーション (特集 放射光が拓く学術--若手人材探訪)
- 光電子顕微鏡を用いた鉄隕石のナノ磁性解析
- 鉄隕石の微細構造と磁性
- 隕石の海洋衝突による初期地球の有機物生成