Alter G M
J Biol Chem. 1983 Dec 25;258(24):14966-73.
In an effort to assess the influence that crystallization may have on protein conformations, optical absorption spectra of crystalline state hemoglobin derivatives have been examined. These spectra were obtained from photoacoustic spectra using a computer-assisted analysis. Comparisons of crystal and solution state hemoglobins using crystal minus solution state difference spectra indicate that the conformations of these proteins are similar in both states. Crystallization does not change the absorption properties of horse oxyhemoglobin or the cyanide and azide adducts of horse and human methemoglobin. Spectra of crystalline methemoglobins, which are prepared by ligand exchange in the crystalline state, are identical to the spectra of the final crystalline state adduct prepared without ligand exchange. Further, the allosteric effector, inositol hexaphosphate, causes the same spectral changes in solution and crystalline state hemoglobins. However, differences between crystal and solution state spectra of both fluoride and aquo methemoglobin are observed. These differences suggest that small but perhaps functionally significant changes in the heme regions of these derivatives accompany crystallization.
为了评估结晶可能对蛋白质构象产生的影响，已对结晶态血红蛋白衍生物的光吸收光谱进行了研究。这些光谱是通过计算机辅助分析从光声光谱中获得的。使用晶体减去溶液态差光谱对晶体态和溶液态血红蛋白进行比较表明，这些蛋白质在两种状态下的构象相似。结晶不会改变马氧合血红蛋白或马和人高铁血红蛋白的氰化物和叠氮化物加合物的吸收特性。通过在结晶态中进行配体交换制备的结晶高铁血红蛋白的光谱与未进行配体交换制备的最终结晶态加合物的光谱相同。此外，变构效应剂肌醇六磷酸在溶液态和结晶态血红蛋白中引起相同的光谱变化。然而，观察到氟化物和水合高铁血红蛋白的晶体态和溶液态光谱之间存在差异。这些差异表明，这些衍生物的血红素区域在结晶过程中发生了微小但可能具有功能意义的变化。
