化学
离解(化学)
血红蛋白
蛋白质亚单位
静水压力
吉布斯自由能
化学计量学
分析化学(期刊)
结晶学
色谱法
物理化学
热力学
生物化学
基因
物理
作者
José Ailton Conceição Bispo,Jose Luis Santos,Gustavo Fraga Landini,Juliana E. Gonçalves,Carlos Francisco Sampaio Bonafe
标识
DOI:10.1016/j.bpc.2006.09.009
摘要
We investigated the thermodynamic features of the classic alkaline dissociation of multimeric hemoglobin (3.1 MDa) from Glossoscolex paulistus (Annelidea) using high hydrostatic pressure. Light scattering measurements up to microscopic thermodynamic equilibrium indicated a high pH dependency of dissociation and association. Electron microscopy and gel filtration corroborated these findings. The volume change of dissociation decreased in absolute values from − 48.0 mL/mol of subunit at pH 6.0 to − 19.2 mL/mol at pH 9.0, suggesting a lack of protein interactions under alkaline conditions. Concomitantly, an increase in pH reduced the Gibbs free energy of dissociation from 37.7 to 27.5 kJ/mol of subunit. The stoichiometry of proton release calculated from the pressure-induced dissociation curves was + 0.602 mol of H+/mol of subunit. These results provide a direct quantification of proton participation in stabilizing the aggregated state of the hemoglobin, and contribute to our understanding of protein–protein interactions and of the surrounding conditions that modulate the process of aggregation.
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