Dong A, Huang P, Caughey B, Caughey W S
Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins 80523.
Arch Biochem Biophys. 1995 Feb 1;316(2):893-8. doi: 10.1006/abbi.1995.1120.
Effects of the binding of O2 and CO to heme iron (II) of deoxy forms and of the oxidation of deoxy forms to aquoiron (III) complexes on the infrared spectra of hemoglobins and myoglobins have been examined. Spectra were measured for aqueous solutions 3-4 mM in heme of human, bovine, and equine hemoglobins and sperm whale, bovine, and equine myoglobins in 10 mM sodium phosphate buffer, pH 7.4, at 20 degrees C. All ligand binding and oxidation reactions resulted in similar spectral shifts in the region 1665 to 1670 cm-1, a portion of the amide I region assignable to beta-turn structure. There were no other significant changes in the amide I region, a finding consistent with no other alterations in secondary structure. The major bands near 1655 cm-1 associated with alpha-helices were consistently at 2 cm-1 lower wavenumber for myoglobins than for hemoglobins. The changes in solution infrared spectra observed in this study may result at least in part from conformational changes at the FG corner associated with movements of F and E helices that have been noted previously in crystal structures.
已研究了氧气和一氧化碳与脱氧形式的血红素铁（II）结合以及脱氧形式氧化为水合铁（III）配合物对血红蛋白和肌红蛋白红外光谱的影响。在20℃下，于pH 7.4的10 mM磷酸钠缓冲液中，对人、牛和马血红蛋白以及抹香鲸、牛和马肌红蛋白的3 - 4 mM血红素水溶液进行了光谱测量。所有配体结合和氧化反应在1665至1670 cm-1区域均导致类似的光谱位移，该区域是酰胺I区域中可归因于β-转角结构的一部分。酰胺I区域没有其他显著变化，这一发现与二级结构没有其他改变一致。与α-螺旋相关的1655 cm-1附近的主要谱带，肌红蛋白的波数始终比血红蛋白低2 cm-1。本研究中观察到的溶液红外光谱变化可能至少部分源于FG转角处的构象变化，这与先前在晶体结构中注意到的F和E螺旋的移动有关。
