SOLUTION STRUCTURES OF FERRIHAEM IN SOME DIPOLAR APROTIC SOLVENTS AND THEIR BINARY AQUEOUS MIXTURES
SOLUTION STRUCTURES OF FERRIHAEM IN SOME DIPOLAR APROTIC SOLVENTS AND THEIR BINARY AQUEOUS MIXTURES
复制标题
DOI：
10.1042/bj1150279
复制
发表时间：
1969-01-01
影响因子：
4.1
通讯作者：
LANTZKE, IR
中科院分区：
文献类型：
--
作者：
BROWN, SB;LANTZKE, IR
1.电导率和紫外和可见光谱技术被用来调查的解决方案结构的辅基的铁血红素蛋白（ferrihaem）在二甲基亚砜，NN-二甲基乙酰胺，NN-二甲基甲酰胺和环丁砜，和某些它们的水性混合物。2.在中性或酸性二甲基亚砜中，氯代血红素是单体，完全解离成Cl−离子和亚铁血红素，二甲基亚砜分子位于铁的第五和第六配位。3.在中性的N，N-二甲基乙酰胺和N，N-二甲基甲酰胺氯血红素是单体，但在很大程度上是未解离的，给出不同的光谱从氯血红素在二甲基亚砜。在酸化时，发生解离，并产生二甲基亚砜类型的光谱。4.在第四种溶剂，环丁砜，研究表明，溶剂的配位能力（配体强度），而不是体介电常数是负责氯代血红素的解离。5.在中性二甲基亚砜-水的混合物中，氯代血红素保持单体和完全解离，光谱是独立的混合物组合物，除了在高的水浓度，当沉淀发生。在碱性二甲基亚砜-水混合物中，其中完整的溶剂混合物范围是可访问的，铁血红素是聚合的（可能是二聚的），光谱取决于溶剂组成。定量分析表明，光谱的变化是由于更换水的一个分子的协调二甲基亚砜每个ferrihaem聚集体，并不涉及两个分子的替代已建议的碱性吡啶-水系统。
1. Conductivity and u.v. and visible spectroscopic techniques were used to investigate the solution structure of the prosthetic group of the ferric haemoproteins (ferrihaem) in dimethyl sulphoxide,NN-dimethylacetamide,NN-dimethylformamide and sulpholane, and certain of their aqueous mixtures. 2. In neutral or acid dimethyl sulphoxide, chlorohaemin is monomeric and completely dissociated into Cl−ion and a ferrihaem species with dimethyl sulphoxide molecules in the fifth and sixth co-ordination positions on iron. 3. In neutralNN-dimethylacetamide andNN-dimethylformamide chlorohaemin is monomeric but is largely undissociated, giving different spectra from that of chlorohaemin in dimethyl sulphoxide. On acidification, dissociation occurs and the dimethyl sulphoxide type of spectrum results. 4. Studies in a fourth solvent, sulpholane, indicate that solvent co-ordinating power (ligand strength) rather than bulk dielectric constant is responsible for dissociation of chlorohaemin. 5. In neutral dimethyl sulphoxide–water mixtures chlorohaemin remains monomeric and completely dissociated, and spectra are independent of mixture composition, except at high water concentrations, when precipitation occurs. In alkaline dimethyl sulphoxide–water mixtures, where the complete solvent mixture range is accessible, ferrihaem is polymeric (probably dimeric) and spectra are dependent on solvent composition. A quantitative analysis indicates that the spectral changes are due to replacement by water of one molecule of co-ordinated dimethyl sulphoxide per ferrihaem aggregate, and do not involve a two-molecule replacement as has been suggested for the alkaline pyridine–water system.