Bianconi A, Congiu-Castellano A, Dell'Ariccia M, Giovannelli A, Morante S, Burattini E, Durham P J
Proc Natl Acad Sci U S A. 1986 Oct;83(20):7736-40. doi: 10.1073/pnas.83.20.7736.
The Fe-site structure variation in the transition from the low-affinity tense (T) quaternary structure to the high-affinity relaxed (R) structure in carp deoxyhemoglobin was studied by analysis of multiple scattering resonances in the XANES (x-ray absorption near edge structure) spectra. High signal-to-noise XANES spectra were measured at the Frascati "wiggler" synchrotron radiation facility. We find that the forces on the Fe active site due to the change of quaternary protein conformation do not induce variations greater than 0.01 A in interatomic Fe-N distances, variations greater than 0.1 A in the Fe displacement toward the heme plane, or the "doming" of the heme. The relevance of these results to the mechanism of protein control of ligand binding is discussed.
通过分析X射线吸收近边结构（XANES）光谱中的多重散射共振，研究了鲤鱼脱氧血红蛋白从低亲和力紧张（T）四级结构向高亲和力松弛（R）结构转变过程中的铁位点结构变化。在弗拉斯卡蒂“摆动器”同步辐射设施上测量了高信噪比的XANES光谱。我们发现，由于四级蛋白质构象变化而施加在铁活性位点上的力，不会导致铁-氮原子间距离的变化大于0.01埃，铁向血红素平面位移的变化大于0.1埃，也不会导致血红素的“隆起”。讨论了这些结果与蛋白质控制配体结合机制的相关性。
