Fronticelli C, Bucci E, Razynska A
Department of Biological Chemistry, University of Maryland, Baltimore School of Medicine 21201.
J Mol Biol. 1988 Jul 20;202(2):343-48. doi: 10.1016/0022-2836(88)90463-9.
In the absence of Cl- in Hepes buffer at pH 7.4, the oxygen affinity of bovine and human hemoglobin is equally sensitive to 2,3-diphosphoglyceric acid. The low oxygen affinity measured for bovine hemoglobin at physiological salt concentration can be explained by the high affinity of Cl- anions for oxygen-linked sites that are absent in human hemoglobin. Bovine hemoglobin can discriminate between the different halogens in the sense that different halide concentrations are necessary to produce the same P50. Competition experiments indicate that the halogens interact with the same oxygen-linked sites. In agreement with the different affinities for halides, the Bohr effect of bovine hemoglobin is larger in the presence of Cl- than in that of Br- and there is good agreement between the number of protons and anions exchanged with the solvent upon oxygenation of bovine hemoglobin.
在pH 7.4的Hepes缓冲液中不存在Cl-时，牛血红蛋白和人血红蛋白的氧亲和力对2,3-二磷酸甘油酸同样敏感。在生理盐浓度下测得的牛血红蛋白低氧亲和力可以通过Cl-阴离子对人血红蛋白中不存在的氧连接位点的高亲和力来解释。牛血红蛋白能够区分不同的卤素，因为产生相同P50需要不同的卤化物浓度。竞争实验表明，卤素与相同的氧连接位点相互作用。与对卤化物的不同亲和力一致，牛血红蛋白在Cl-存在下的玻尔效应比在Br-存在下更大，并且在牛血红蛋白氧合时与溶剂交换的质子和阴离子数量之间存在良好的一致性。
