Abstract

It was found that a decrease in the concentration of extracellular Ca²⁺ ([Ca²⁺]_out) caused an increase in the surface charge of the erythrocyte membrane, which was accompanied by a change in the conformation of heme and globin, as well as in a redistribution of hemoglobin in the cell (a decrease in the optical path difference (OPD) of the cytoplasm and the content of the membrane-associated hemoglobin). It was also found that when [Ca²⁺]_out was decreased from 10^–3 to 10^–6 M, the morphology of the erythrocyte practically did not change, the ζ-potential increased from –15.4 ± 0.2 to –14.5 ± 0.3 mV (at [Ca²⁺]_out decrease from 10^–3 to 5 × 10^–4 M), and the OPD of the cell cytoplasm decreased. A decrease in [Ca²⁺]_out to 10^–6 M changed the conformation of heme, as well as the distribution of hemoglobin in the erythrocyte, as assessed by a decrease in the symmetric vibrations of the side CH groups of pyrrole semirings and an increase in the vibrations of the vinyl groups of hemoporphyrin as well as the affinity of heme to ligands. At the same time, the probability of finding heme in a flat conformation did not change, while the rigidity of its protein surrounding decreased. When [Ca²⁺]_out was decreased from 10^–3 to 10^–4 M, a change in the globin conformation was observed as a decrease in the ordering of the CH groups of globin amino acids, an increase in the globin packing density, and the polarity of the globin surrounding. When erythrocytes were incubated in a medium containing [Ca²⁺]_out = 10^–6 M, the maximum intensity of the Raman scattering of erythrocyte hemoglobin (Raman spectrum bands at 1375 and 1580 cm^–1) was detected in the center of the cell; it was 2.6 times less than that of erythrocytes incubated in a medium containing [Ca²⁺]_out = 10^–3 M.

中文翻译：

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细胞外Ca2+在调节红细胞内血红蛋白分布和构象中的作用

摘要

发现细胞外Ca ²⁺ ([Ca ²⁺ ] _out )浓度降低导致红细胞膜表面电荷增加，伴随着血红素和珠蛋白构象的变化，如细胞中血红蛋白的重新分布（细胞质的光程差（OPD）和膜相关血红蛋白含量的减少）。还发现当 [Ca ²⁺ ] _out从 10 ^–3减少到 10 ^–6 M 时，红细胞的形态几乎没有改变，ζ 电位从 –15.4 ± 0.2 增加到 –14.5 ± 0.3 mV （在 [Ca ²⁺ ]_出从 10 ^–3减少到 5 × 10 ^–4 M)，细胞质的 OPD 降低。内[Ca的降低²⁺ ]_出到10 ^-6中号改变血红素的构象，以及血红蛋白的红细胞的分布，如通过降低在半环的吡咯和侧CH基团的对称振动评估增加血卟啉乙烯基的振动以及血红素与配体的亲和力。同时，在扁平构象中发现血红素的概率没有变化，而其周围蛋白质的刚性降低。当 [Ca ²⁺ ] _out从 10 ^–3减少到 10 ^–4M，观察到珠蛋白构象的变化是珠蛋白氨基酸的 CH 基团排序的减少，珠蛋白堆积密度的增加，以及周围珠蛋白的极性。当红细胞在含有 [Ca ²⁺ ] _out = 10 ^–6 M的培养基中培养时，红细胞血红蛋白的最大拉曼散射强度（拉曼光谱带在 1375 和 1580 cm ^{–1 处}）在细胞中心被检测到; 它比在含有 [Ca ²⁺ ] _out = 10 ^–3 M的培养基中培养的红细胞少 2.6 倍。