关于氧化与甲基球蛋白的可逆结合的机制研究
L E Laverman1, A Wanat, J Oszajca
1Contribution from the Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, USA.
Journal of the American Chemical Society
|July 18, 2001
概括
甲基球蛋白 (metMb) 可逆地与氧化 (NO) 结合,形成一个酸添加物. 动力学研究揭示了NO结合和释放的分离机制,体积和变化显著.
科学领域:
- 生物化学 生物化学
- 化学动力学 化学动力学
- 蛋白质 - 配体相互作用
背景情况:
- 甲基球蛋白 (metMb) 是一种铁血蛋白.
- 氧化 (NO) 是一种生物信息分子.
- 在生理pH值下,甲基球蛋白可逆地与NO结合,形成一个酸添加物 (metMb(NO)) .
研究的目的:
- 为了研究氧化与甲基球蛋白的结合和解离的动力学.
- 为了确定这些反应的激活参数 (DeltaH,DeltaS,DeltaV).
- 为了阐明NO与甲米oglobin结合的反应机制.
主要方法:
- 激光闪光灯的光解法.
- 停止流动动学的动力学
- 高压研究 高压研究
- 没有陷的实验.
主要成果:
- 关联反应 (metMb + NO) 显示了激活参数:DeltaH(on) ≈65kJ/mol,DeltaS(on) ≈60J/mol·K,以及DeltaV(on) ≈20cm3/mol. 这些都是DeltaH (在) ≈65kJ/mol·K,DeltaS(on) ≈60J/mol·K,以及DeltaV (在) ≈20cm3/mol.
- 分离反应 (metMb(NO)) 产生了以下激活参数:DeltaH(off) = 76 kJ/mol,DeltaS(off) ≈ 41 J/mol·K,和DeltaV(off) = 20 cm3/mol. 这些参数是:DeltaH(off) = 76 kJ/mol,DeltaS(off) ≈ 41 J/mol·K,和DeltaV(off) = 20 cm3/mol.
- "启动"反应的大量正的DeltaS和DeltaV值表明存在分离性连接体替代机制,涉及水的先前分离.
结论:
- NO与甲基球蛋白的结合和分离都遵循一个限制性分离机制.
- 从第六个协调站点释放水之前没有约束.
- 这些发现与对模型系统和其他金属蛋白的研究一致.
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