Fe-Co杂化血红蛋白E11-Val甲基质子~1H NMR谱峰归属及蛋白溶液构象的研究

THE ASSIGNMENT FOR THE RESONANCE PEAKS OF E11-VAL METHYL PROPONS OF Fe(Ⅱ)-Co(Ⅱ) HYBRID HEMOGLOBINS AND THE STUY OF THEIR CONFORM ATION IN SOLUTION

在500MHz^1H NMR仪上对HbA,CoHb和对称与不对称的Fe-Co杂化血红蛋白在去氧和一氧化碳配位时环形电流效应对蛋白Ell-Val甲基共振峰的影响进行了研究,将-1.0ppm峰归属于β(Co)的二个甲基质子,-1.55ppm和-2.35ppm的峰归属于α(Co)γ_1CH_3和γ_2CH_3,-1.15ppm与-2.05ppm的峰归属为α(Fe-Co)的γ_1CH_3与α_2CH_3共振峰,-1.52ppm与-2.15ppm的峰指定为β(Fe-Co)的γ_1CH_3与γ_2CH_3.根据归属对蛋白在去氧和一氧化碳配位时其溶液构象变化进行了研究,发现CO配位于β(Fe)比配位于α(Fe)使E11-Val甲基质子化学位移发生更大改变.

The effects of ring current shift on the resonance peaks of Ell-val methyl protons of hemoglobins for symmetric and asymmetric Fe-Co hybrid hemoglodins in deoxy and carbon monoxide form have been studied with 500 MHz 1H NMR spectroscopy. The broader resonance at around-1 .Oppm have been assigned to two methyl protons of β(Co).similarly the resonances at about-1.55 and -2.35ppm have been assigned to γ1CH3 and γ2CH3 of α(Co) respectively. In CO form the peaks at about -1.15ppm and -2.05ppm can be considered as γ1CH3 and γ2 CH3 of α(Fe-CO), the peaks at around -1.52ppm and -2.15ppm can be derived from γ1 CH3 and γ2CH3 of β (Fe-CO). According to the assignment of hemoglobins in deoxy and carbon monoxide form, the conformational change of proteins in solution has been also studied. It found that the larger change in chemical shift of methyl protons of Ell-val when the CO binded on β(Fe) than that on α(Fe).