一氧化碳从人碳氧血红蛋白的α亚基和β亚基上的解离。

The dissociation of carbon monoxide from the alpha and the beta subunits of human carbonmonoxy hemoglobin.

作者信息

Samaja M, Rovida E

机构信息

Dipartimento di Scienze e Tecnologie Biomediche, Universita' di Milano, Italy.

出版信息

Biochem Biophys Res Commun. 1987 Nov 13;148(3):1196-201. doi: 10.1016/s0006-291x(87)80259-0.

DOI:10.1016/s0006-291x(87)80259-0

PMID:3689391

Abstract

We have measured the intrinsic CO dissociation rates from the subunits of the human hemoglobin tetramers (alpha CO beta NO)2 and (alpha NO beta CO)2 using microperoxidase and a stopped-flow spectrophotometer. The dissociation of NO is negligible. The rate constants for the and the subunits are similar (0.014 s-1 vs. 0.011 s-1, respectively, at pH 7, 20 C; and 0.016 s-1 for both in the presence of inositol hexaphosphate), indicating that they are equivalent in the first step of the CO dissociation. Therefore, the chain unequality observed in the third and fourth steps (Samaja, M., Rovida, E., Niggeler, M., Perrella, M., and Rossi-Bernardi, L. (1987). J. Biol. Chem.: 262, 4528-4533) are not due to the intrinsic properties of the subunits, but to the conformational state of the molecule.

摘要

我们使用微过氧化物酶和停流分光光度计测量了人血红蛋白四聚体（αCOβNO）2和（αNOβCO）2亚基的固有CO解离速率。NO的解离可忽略不计。α和β亚基的速率常数相似（在pH 7、20℃时，分别为0.014 s-1和0.011 s-1；在存在肌醇六磷酸的情况下，两者均为0.016 s-1），这表明它们在CO解离的第一步中是等效的。因此，在第三步和第四步中观察到的链不平等现象（Samaja, M., Rovida, E., Niggeler, M., Perrella, M., and Rossi-Bernardi, L. (1987). J. Biol. Chem.: 262, 4528 - 4533）并非由于亚基的固有特性，而是由于分子的构象状态。