(一)血红蛋白在血液中转运氧

➢血红蛋白(hemoglobin, Hb)的主要功能是在血液中结合并转运氧气。

➢红细胞成熟期间产生大量的Hb (含3亿个 Hb ),Hb以高浓度(约34%) 溶于红细胞溶胶中。

➢动脉血中Hb约为96%氧饱和度,静脉血中氧饱和度为64%,向组织释放6.5 ml O2/100 ml血液。

(二)血红蛋白的结构

Hb亚基:α2β2四聚体,每个亚基都有一个血红素辅基和一个氧结合部位

与Mb相似- - - 折叠的复杂性

不同亚基之间相互作用强,由疏水相互作用主导

分子近球体

(三)结合氧时血红蛋白发生构象变化

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**T态:**紧张态- - 去氧Hb亚基(专一性氢键,盐桥- - 稳定作用)

**R态:**松弛态(与氧结合能力强 - - 正协同效应)(中央孔穴变小)

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(四)血红蛋白与氧结合是协同的

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协同效应- - 针对多亚基蛋白,属于 别构效应

(五)协同性配体结合可以定量描述

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Mb:P50=2 torr

Hb:P50=26 torr

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(六)协同性结合机制的两个模型

齐变模型(MWC):协同模型

序变模型(KNF):渐变模型

(七)血红蛋白 转运H+和CO2- - -Bohr效应

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Bohr效应

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