Experimental resolution of cooperative free energies for the ten ligation species of cobalt(II)/iron(II)-CO hemoglobin.
Experimental resolution of cooperative free energies for the ten ligation species of cobalt(II)/iron(II)-CO hemoglobin.
复制标题
钴(II)/铁(II)-CO 血红蛋白十种连接物质的协同自由能的实验解析。
DOI：
10.1021/bi00243a030
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发表时间：
1991
期刊：
影响因子：
2.9
通讯作者：
Ackers,GK
中科院分区：
文献类型：
--
作者：
Speros,PC;LiCata,VJ;Yonetani,T;Ackers,GK
Philip C. Speros，** Vince J. LiCata，* Takashi Yonetani，8和GaryK。Ackers*· 1 Department of Biology，The Johns霍普金斯University，巴尔的摩，马里兰州21218，and Department of Biochemistry and Biophysics，University of Pennsylvania School of Medicine，Philadelphia，Pennsylvania 19104-6089 1991年2月21日接收; 1991年4月9日接收修订的Mandarin pt摘要：测定了Co（II）/Fe（II）-CO体系中人类血红蛋白10种连接物质的协同自由能。在这个系统中，含有未连接的钴血红素的亚基与天然存在的亚铁血红素（与一氧化碳连接）共存于同一个四聚体中。由连接和未连接亚基的10种结构独特组合组成的四聚体根据其二聚体-四聚体组装自由能进行表征。通过使用组装和连接之间的热力学联系，使用实验解析值来获得相应的合作自由能（即，连接的实际自由能与固有值的总和贡献之间的差异）。所获得的结果通常与先前关于该相同系统的发现雅阁（Imai等人，1980年）。本研究通过解决双连接四聚体的每个构型异构体的合作性质，扩展了这一早期的工作。发现10种连接物质根据组合代码分布成5个离散的协同自由能级，作为特殊情况，所述组合代码包括先前用氰基高铁血红蛋白和锰取代的血红蛋白发现的代码（Smith等人，1987年; Daughthorn等人，1991年）。这种分布表现出在正常亚铁血红蛋白的氧合中发现的额外特征，包括四级增强效应（米尔斯和阿克斯，1979 a，B）。这些结果以及以下论文的结果（Doyle等人，1991），强烈支持这样的前提，即一组共同的定性规则支配血红蛋白中的协同相互作用，而不管血红素携带的金属和与其结合的配体。
Philip C. Speros,** Vince J. LiCata,* Takashi Yonetani, 8 and GaryK. Ackers*· 1 Department of Biology, The Johns Hopkins University, Baltimore, Maryland 21218, andDepartment of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6089 Received February 21, 1991; Revised Manuscript Received April 9, 1991 abstract: Cooperative free energies have been determined for the 10 ligation species of human hemoglobin in the Co (II)/Fe (II)-CO system. In this system, subunits containing unligated cobaltous hemes coexist in the same tetramer with naturally occurring ferrous hemes that are ligated with carbon monoxide. Tetramers comprising the 10 structurally unique combinations of ligated and unligated subunits were characterized in terms of their dimer-tetramer assembly free energies. By use of the thermodynamic linkage between assembly and ligation, the experimentally resolved values were used to obtain the corresponding cooperative free energies (ie, the differences between actual free energies of ligation and the summed contributions of intrinsic values). The results obtained are in general accord with previous findings on this same system (Imai et al., 1980). The present study extends this earlier work by resolving the cooperative properties of each configurational isomer of the doubly ligated tetramers. The 10 ligation species were found to distribute into 5 discrete cooperative free energy levels according to a combinatorial code which includes, as a special case, the code found previously with cyanomethemoglobinand manganese-substituted hemoglobin (Smith et al., 1987; Daugherty et al., 1991). This distribution exhibits additional characteristics found inthe oxygenation of normal ferrous hemoglobin including the quaternary enhancement effect (Mills & Ackers, 1979a, b). These results, and those of the following paper (Doyle et al., 1991), strongly support the premise that a common set of qualitative rules governs the cooperative interactions in hemoglobin irrespective of the metal carried by the heme and the ligands bound to it.