Srivastava T S, Tyagi S, Nath A
Proc Natl Acad Sci U S A. 1977 Nov;74(11):4996-5000. doi: 10.1073/pnas.74.11.4996.
An important feature of Perutz's trigger mechanism for cooperativity in the reversible oxygenation of hemoglobin (Hb) is the tension along the histidine--metal linkage in deoxyHb and deoxycobaltohemoglobin (deoxy CoHb), supposedly due to the pull exerted by the globin on the metal atom. We have attempted to verify the existence of this pull by studying the emission Mössbauer spectra of deoxy 57CoHb and oxy 57 CoHb at different temperatures. The emission Mössbauer spectrum for none of the cobalt Hbs agrees with the absorption spectrum of the corresponding iron analog and, moreover, the spectrum of deoxy 57CoHb is characteristic of the intermediate-spin iron. These observations indicate that the daughter 57Fe atom is "frozen" almost in the same spatial situation as that of the parent 57Co. The protein is apparently holding the cobalt atom in position rather rigidly and, after the electron-capture decay of the 57Co atom, the protein does not permit the daughter 57Fe to move to a position characteristic of the iron atom.
佩鲁茨提出的血红蛋白（Hb）可逆氧化协同作用触发机制的一个重要特征是脱氧血红蛋白（deoxyHb）和脱氧钴血红蛋白（deoxy CoHb）中沿组氨酸 - 金属键的张力，推测这是由于球蛋白对金属原子施加的拉力所致。我们试图通过研究不同温度下脱氧57CoHb和氧合57CoHb的发射穆斯堡尔谱来验证这种拉力的存在。没有一种钴血红蛋白的发射穆斯堡尔谱与相应铁类似物的吸收谱一致，此外，脱氧57CoHb的谱具有中间自旋铁的特征。这些观察结果表明，子体57Fe原子几乎“冻结”在与母体57Co相同的空间位置。蛋白质显然将钴原子相当牢固地固定在位置上，并且在57Co原子的电子俘获衰变后，蛋白质不允许子体57Fe移动到铁原子特有的位置。
