An investigation of human oxyhemoglobin beta tetramer dissociation using haptoglobin binding.
An investigation of human oxyhemoglobin beta tetramer dissociation using haptoglobin binding.
复制标题
使用触珠蛋白结合研究人氧合血红蛋白β四聚体解离。
DOI：
10.1016/s0006-291x(88)80860-x
复制
发表时间：
1988
影响因子：
3.1
通讯作者：
McDonald,MJ
中科院分区：
文献类型：
--
作者：
Michalski,LA;McDonald,MJ
使用触珠蛋白作为大分子探针，研究在 0.1 M 磷酸钾缓冲液中从四聚体形成人氧合血红蛋白 β 链二聚体，温度为 20°C，pH 7 和 pH 8。监测结合珠蛋白与 β 血红素链（2.5 和 5 微摩尔）混合后的光谱变化，结果显示吸光度总体下降，同时 Soret 光谱峰从 415 nm 移动到 417 nm。吸光度下降的幅度与 β 浓度成正比；时间进程在 pH 8 时比在 pH 7 时始终产生更大的颜色。在 pH 8 时，可以看到两个指数阶段 0.47 min−1 和 0.084 min−1，其速率随浓度保持不变。相比之下，在 pH 7 时只有一个指数过程明显，产生 0.21 min−1 的一阶速率常数。我们通过分光光度法跟踪了 β 链四聚体到二聚体的解离反应，从而提供了有关该步骤对血红蛋白组装的贡献的信息。
Haptoglobin was used as a macromolecular probe to investigate the formation of human oxyhemoglobin beta chain dimers from tetramers in 0.1 M potassium phosphate buffer, 20°C at pH 7 and pH 8. Monitoring of spectral changes upon mixing haptoglobin with beta heme chains (2.5 and 5 micromolar) revealed an overall decrease in absorbance accompanied by a shift of the Soret spectral peak from 415 to 417 nm. The magnitude of the absorbance decrease was proportional to the beta concentration; the time courses consistently yielded greater color at pH 8 than at pH 7. At pH 8, two exponential phases of 0.47 min−1and 0.084 min−1were seen whose rates remained invariant with concentration. In contrast, only one exponential process was evident at pH 7, yielding a first order rate constant of 0.21 min−1. We have spectrophotometrically followed the beta chain tetramer to dimer dissociation reaction, thus providing information about the contribution of this step to hemoglobin assembly.