Investigations of photolysis and rebinding kinetics in myoglobin using proximal ligand replacements
Investigations of photolysis and rebinding kinetics in myoglobin using proximal ligand replacements
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DOI：
10.1021/bi049077g
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发表时间：
2004-08-31
期刊：
影响因子：
2.9
通讯作者：
Champion, PM
中科院分区：
文献类型：
--
作者：
Cao, WX;Ye, X;Champion, PM
我们利用激光闪光光解和时间分辨拉曼光谱的CO结合的H93 G肌红蛋白（Mb）突变体的研究的影响，近端配体上的CO再结合动力学。在H93 G突变体中，其中与蛋白质的近端连接被消除并且血红素可以结合外源配体（例如，咪唑、4-溴咪唑、吡啶或二溴吡啶），我们在10 ns至10 ms的时间窗内观察到对CO再结合动力学的显著影响。共振拉曼光谱的各种H93 G Mb复合物也提出了帮助解释的动力学结果。对于CO结合的H93 G（二溴吡啶），我们观察到一个快速的大振幅双生相，其基本CO再结合速率在293 K时比野生型MbCO快45倍。在10 ns的photoproduct拉曼光谱的CO结合的H93 G（二溴吡啶）的铁近端配体的振动模式的情况下支持的假设，近端连接有显着的影响动力学的双原子配体结合血红素。
We use laser flash photolysis and time-resolved Raman spectroscopy of CO-bound H93G myoglobin (Mb) mutants to study the influence of the proximal ligand on the CO rebinding kinetics. In H93G mutants, where the proximal linkage with the protein is eliminated and the heme can bind exogenous ligands (e.g., imidazole, 4-bromoimidazole, pyridine, or dibromopyridine), we observe significant effects on the CO rebinding kinetics in the 10 ns to 10 ms time window. Resonance Raman spectra of the various H93G Mb complexes are also presented to aid in the interpretation of the kinetic results. For CO-bound H93G(dibromopyridine), we observe a rapid large-amplitude geminate phase with a fundamental CO rebinding rate that is similar to45 times faster than for wild-type MbCO at 293 K. The absence of an iron proximal ligand vibrational mode in the 10 ns photoproduct Raman spectrum of CO-bound H93G(dibromopyridine) supports the hypothesis that proximal ligation has a significant influence on the kinetics of diatomic ligand binding to the heme.