通过X射线吸收近边结构光谱法检测变构效应剂对单峰驼亚铁亚硝基血红蛋白血红素构象的影响。

Influence of allosteric effectors on the heme conformation of dromedary ferrous nitrosylhemoglobin detected by XANES spectroscopy.

作者信息

Congiu Castellano A, Della Longa S, Bianconi A, Barteri M, Burattini E, Ascenzi P, Coletta M, Santucci R, Amiconi G

机构信息

Department of Physics, University of Roma, La Sapienza, Italy.

出版信息

Biochim Biophys Acta. 1991 Oct 25;1080(2):119-25. doi: 10.1016/0167-4838(91)90137-o.

DOI:10.1016/0167-4838(91)90137-o

PMID:1932085

Abstract

The changes of the Fe heme-active site conformation of dromedary (Camelus dromedarius) nitrosylhemoglobin (HbNO) induced by inositol hexakisphosphate (IHP) and chlofibric acid (CFA) have been studied by using X-ray absorption near-edge structure (XANES) spectroscopy. Structural information has been determined by multiple scattering analysis of the Fe K-edge XANES spectra. The proximal histidine is found to move away from iron centers by about 0.4 Angstrom on the average over the four hemes upon binding of CFA or stoichiometric amount of IHP. In molar excess of polyanion or in the simultaneous presence of IHP, CFA and chloride, the proximal histidine moves back to a position very close to that observed in pure buffer; yet, the structure modulation induced by the allosteric effectors is not completely reversible. Such findings parallel with the functional properties and the spectroscopic (e.g., EPR and absorbance) characteristics of HbNO.

摘要

利用X射线吸收近边结构（XANES）光谱研究了肌醇六磷酸（IHP）和氯贝酸（CFA）诱导的单峰驼（Camelus dromedarius）亚硝酰血红蛋白（HbNO）的铁血红素活性位点构象变化。通过对铁K边XANES光谱的多重散射分析确定了结构信息。发现结合CFA或化学计量的IHP后，四个血红素上的近端组氨酸平均从铁中心移开约0.4埃。在多阴离子摩尔过量或同时存在IHP、CFA和氯离子的情况下，近端组氨酸移回到非常接近纯缓冲液中观察到的位置；然而，变构效应剂诱导的结构调节并非完全可逆。这些发现与HbNO的功能特性和光谱（如EPR和吸光度）特征相似。