Smith F R, Simmons K C
Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill 27599-7260.
Proteins. 1994 Mar;18(3):295-300. doi: 10.1002/prot.340180310.
Cyanomet human hemoglobin has been crystallized at a chloride ion concentration and pH similar to physiological conditions. Molecular replacement calculations definitively show that the hemoglobin subunits are arranged in the Y quaternary form recently discovered in carbon monoxy hemoglobin Yp-silanti (beta 99 Asp-Tyr), and subsequently observed in carbon monoxy normal human hemoglobin crystallized at low ionic strength and low pH. The structure has been refined at 2.09 A resolution to an R-value of 0.232, and further refinement is currently underway. Although the refinement is not yet complete, our results are the first indication that the Y structure may represent an important quaternary form of liganded hemoglobin under physiological buffer conditions. These results suggest the need for a reexamination of structure-function correlations in the hemoglobin system.
氰化高铁人血红蛋白已在与生理条件相似的氯离子浓度和pH值下结晶。分子置换计算明确表明，血红蛋白亚基以最近在一氧化碳血红蛋白Yp-silanti（β99天冬氨酸-酪氨酸）中发现的Y四级结构形式排列，随后在低离子强度和低pH值下结晶的一氧化碳正常人血红蛋白中也观察到这种结构。该结构已在2.09 Å分辨率下精修至R值为0.232，目前正在进行进一步精修。虽然精修尚未完成，但我们的结果首次表明，Y结构可能代表生理缓冲条件下配体血红蛋白的一种重要四级结构形式。这些结果表明需要重新审视血红蛋白系统中的结构-功能相关性。
