Colombo M F, Sanches R
Instituto de Biociências, Letras e Ciências Exatas, UNESP, S. José do Rio Preto, Brazil.
Biophys Chem. 1990 May;36(1):33-9. doi: 10.1016/0301-4622(90)85004-p.
The equilibrium and kinetics of methemoglobin conversion to hemichrome induced by dehydration were investigated by visible absorption spectroscopy. Below about 0.20 g water per g hemoglobin only hemichrome was present in the sample; above this value, an increasing proportion of methemoglobin appeared with the increase in hydration. The transition between the two derivatives showed a time-dependent biphasic behavior and was observed to be reversible. The rates obtained for the transition of methemoglobin to hemichrome were 0.31 and 1.93 min-1 and for hemichrome to methemoglobin 0.05 and 0.47 min-1. We suggest that hemichrome is a reversible conformational state of hemoglobin and that the two rates observed for the transition between the two derivatives reflect the alpha- and beta-chains of hemoglobin.
通过可见吸收光谱法研究了脱水诱导高铁血红蛋白转化为半色素的平衡和动力学。在每克血红蛋白约0.20克水以下，样品中仅存在半色素；高于此值时，随着水合作用的增加，高铁血红蛋白的比例增加。两种衍生物之间的转变表现出时间依赖性的双相行为，并且观察到是可逆的。高铁血红蛋白向半色素转变的速率分别为0.31和1.93分钟-1，半色素向高铁血红蛋白转变的速率为0.05和0.47分钟-1。我们认为半色素是血红蛋白的一种可逆构象状态，并且观察到的两种衍生物之间转变的两种速率反映了血红蛋白的α链和β链。
