Quaternary structure regulates hemin dissociation from human hemoglobin.

摘要: Rate constants for hemin dissociation from the alpha and beta subunits of native recombinant human hemoglobins were measured as a function protein concentration at pH 7.0, 37 degrees C, using H64Y/V68F apomyoglobin acceptor reagent. Hemin rates also isolated chains hemoglobin tetramers stabilized by subunit fusion. The rate constant in increases 1.5 h-1 high to 15 dimers low concentrations. is significantly smaller (0.3-0.6 h-1) shows little dependence on concentration. Recombinant containing fused di-alpha remain tetrameric under all concentrations show loss similar those observed wild-type Rates monomeric are much greater, 12 40 h-1, respectively, 7, C. Aggregation monomers form alpha1beta1 greatly stabilizes bound chains, decreasing its approximately 20-fold. In contrast, dimer formation has stabilizing effect binding subunits. A significant reduction does occur after alpha1beta2 interface hemoglobin. These results suggest that may have evolved lose heme rapidly red cell lysis, allowing prosthetic group be removed serum albumin apohemopexin.