Vitrano E, Cupane A, Cordone L
J Mol Biol. 1984 Dec 25;180(4):1157-71. doi: 10.1016/0022-2836(84)90275-4.
We have studied the effects of organic cosolvents (monohydric alcohols and formamide) on the oxygen equilibrium of bovine haemoglobin and have compared them with the effects of the same cosolvents on the oxygen equilibrium of human haemoglobin. Our results indicate: (1) that in agreement with previous suggestions, the lower affinity of bovine haemoglobin for oxygen is not due to an increased number of salt bridges stabilizing the T structure; (2) that, following T----R transition, more hydrophobic surface is exposed to the solvent by bovine than by human haemoglobin. We suggest, therefore, that a relevant role in keeping the oxygen affinity of bovine haemoglobin lower than that of human haemoglobin is played by the higher free energy needed to expose this more hydrophobic surface to the solvent. We stress, however, that our analysis does not enable us to say which particular amino acid residues are concerned in these effects.
我们研究了有机助溶剂（一元醇和甲酰胺）对牛血红蛋白氧平衡的影响，并将其与相同助溶剂对人血红蛋白氧平衡的影响进行了比较。我们的结果表明：（1）与之前的观点一致，牛血红蛋白对氧的亲和力较低并非由于稳定T结构的盐桥数量增加；（2）在T→R转变后，牛血红蛋白比人血红蛋白向溶剂暴露更多的疏水表面。因此，我们认为，将这个更多的疏水表面暴露于溶剂所需的更高自由能在使牛血红蛋白的氧亲和力低于人血红蛋白方面发挥了相关作用。然而，我们强调，我们的分析无法让我们说出哪些特定的氨基酸残基与这些效应有关。
