Effect of heme and non-heme ligands on subunit dissociation of normal and carboxypeptidase-digested hemoglobin. Gel filtration and flash photolysis studies.
Effect of heme and non-heme ligands on subunit dissociation of normal and carboxypeptidase-digested hemoglobin. Gel filtration and flash photolysis studies.
复制标题
血红素和非血红素配体对正常和羧肽酶消化的血红蛋白亚基解离的影响。
DOI：
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发表时间：
1974
影响因子：
4.8
通讯作者：
C. Spagnuolo
中科院分区：
文献类型：
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作者：
E. Chiancone;N. M. Anderson;E. Antonini;J. Bonaventura;C. Bonaventura;M. Brunori;C. Spagnuolo
用凝胶过滤法研究了正常人血红蛋白和羧肽酶消化人血红蛋白在几种实验条件下的解离。这些包括（a）不同的衍生物，特别是脱氧血红蛋白、氧合血红蛋白和CO血红蛋白，（B）溶剂组成和pH的变化，以及（c）肌醇六磷酸的添加。在正常血红蛋白中，与以前的结果一致，脱氧衍生物比氧或CO衍生物解离少得多。这种差异在某些消化的血红蛋白中也观察到，但在那些蛋白质中趋于消失，其中由于广泛消化，伴随配体结合的构象变化被消除。正常和消化的血红蛋白的解离受溶剂组合物的影响，在pH值接近8时最低，并且通过添加肌醇六磷酸而降低。平行闪光光解实验，在相同的条件下进行的凝胶过滤研究中使用的那些，表明快速反应材料的外观平行解离成二聚体在正常血红蛋白。在正常和消化的血红蛋白条件下，减少解离减少快速反应物质的分数。在消化的血红蛋白中，快速反应物质的分数可能比二聚体的量高得多，这表明在这些情况下，四聚体可能快速反应。数据再次指出，羧基末端残基在维持血红蛋白亚基结构和与之相关的相互作用中起着关键作用。
Abstract The dissociation of normal and carboxypeptidase-digested human hemoglobin has been studied by gel filtration under several experimental conditions. These include (a) different derivatives, notably deoxy-, oxy-, and CO-hemoglobin, (b) changes in solvent composition and in pH, and (c) addition of inositol hexaphosphate. In normal hemoglobin, in agreement with previous results, the deoxygenated derivative is much less dissociated than the oxy or CO ones. This difference is observed also in some of the digested hemoglobins, but tends to vanish in those proteins in which, as a result of extensive digestion, the conformational change accompanying ligand binding is abolished. The dissociation of normal and digested hemoglobins is affected by solvent composition, is at a minimum at pH near 8, and is decreased by the addition of inositol hexaphosphate. Parallel flash photolysis experiments, performed under conditions identical with those used in the gel filtration studies, indicate that the appearance of quickly reacting material parallels dissociation into dimers in normal hemoglobin. Both in normal and digested hemoglobins conditions which decrease dissociation decrease the fraction of rapidly reacting material. In the digested hemoglobins the fraction of rapidly reacting material may be much higher than can be accounted for by the amount of dimers, indicating in these cases that the tetramers may be rapidly reacting. The data point once again to the critical role of the COOH-terminal residues in maintaining the subunit structure of hemoglobin and the interaction effects associated with it.