Ligand binding and release of an analogue of 2,3-diphosphoglycerate from human hemoglobin.
Ligand binding and release of an analogue of 2,3-diphosphoglycerate from human hemoglobin.
复制标题
配体结合并从人血红蛋白中释放 2,3-二磷酸甘油酸类似物。
DOI：
10.1016/s0021-9258(19)44814-x
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发表时间：
1972
期刊：
影响因子：
--
通讯作者：
Q. Gibson
中科院分区：
文献类型：
--
作者：
R. MacQuarrie;Q. Gibson
荧光物质 8-羟基-1,3,6-芘三磺酸盐 (HPT) 已被证明可以与脱氧血红蛋白结合，化学计量为每个血红蛋白四聚体 1 个 HPT 分子。它以相同的化学计量被2,3-二磷酸甘油酸酯和肌醇六磷酸酯取代。当添加到低离子强度的人血红蛋白溶液中时，它会降低氧亲和力。 HPT 已用于研究与一氧化碳结合相关的阴离子释放。这种情况发生在 pH 6 时与血红蛋白 A 反应的后期，可能是在 3 个 CO 分子结合之后，而在 pH 7.5 时则稍早一些。 des-his(β146) 血红蛋白、广岛血红蛋白 (β146asp)、切萨皮克 (α92leu) 和用对汞苯甲酸盐处理的血红蛋白 A 的释放较早。在用一氧化碳进行静态滴定时，配体结合和阴离子释放之间存在良好的比例。以氧作为配体，在低配体浓度的动力学实验中，氧结合和阴离子释放之间几乎没有或没有滞后。详细分析表明需要两种以上的血红蛋白构象才能解释结果。由于组合速度常数，CO 结合反应中协同性的主要动力学贡献发生在 3 个 CO 分子结合后。
The fluorescent substance 8-hydroxy-1,3,6-pyrenetrisulfonate (HPT) has been shown to combine with deoxyhemoglobin with a stoichiometry of 1 molecule of HPT per hemoglobin tetramer. It is displaced with the same stoichiometry by 2,3-diphosphoglycerate and by inositol hexaphosphate. When added to human hemoglobin solutions of low ionic strength it diminishes oxygen affinity. HPT has been used to study anion release associated with carbon monoxide binding. This occurs late in the reaction with hemoglobin A at pH 6, probably after 3 molecules of CO have been bound, and somewhat earlier at pH 7.5. Release is earlier with des-his(β146) hemoglobin, hemoglobins Hiroshima (β146asp), Chesapeake (α92leu), and hemoglobin A treated withp-mercuribenzoate. In static titrations with carbon monoxide there was good proportionality between ligand binding and anion release. With oxygen as ligand there was little or no lag between oxygen binding and anion release in kinetic experiments at low ligand concentrations. Detailed analysis suggests that more than two hemoglobin conformations are required to account for the results. The chief kinetic contribution to cooperativity in the CO binding reaction due to the combination velocity constants occurs after binding of 3 CO molecules.