Salhany J M
Biochim Biophys Acta. 1978 Jun 21;534(2):239-45. doi: 10.1016/0005-2795(78)90006-5.
A new experiment is presented in which the kinetics of iron hexacyanide release is measured from partially oxidized intermediates of human deoxy hemoglobin (T state). The intermediates were generated by briefly exposing a solution of hemoglobin and dithionite to various concentrations of ferricyanide at 6 degrees C in 0.1 M phosphate buffer, pH 7. The reaction of the residual dithionite with the partially oxidized intermediates was limited by the release of ferrocyanide and was strongly biphasic with about 75% fast phase and 25% slow and with the two phases differing in rate by a factor of 26. The predominance of rapid over slow phase is the result of a wide (approx. factor of 5) difference in the kinetics of oxidation of the alpha and beta chains by ferricyanide and is not due to heme-heme interaction. This experimental approach appears to offer a clear example of wide kinetic differences between the two types of subunits within the deoxy quaternary structure of human hemoglobin, uncomplicated by strong cooperative effects.
本文介绍了一项新实验，该实验测量了从人脱氧血红蛋白（T态）的部分氧化中间体释放铁氰化物的动力学。中间体是通过在6℃、pH值为7的0.1M磷酸盐缓冲液中，将血红蛋白和连二亚硫酸盐的溶液短暂暴露于不同浓度的铁氰化物中产生的。残余连二亚硫酸盐与部分氧化中间体的反应受亚铁氰化物释放的限制，且呈强烈的双相性，约75%为快相，25%为慢相，两相速率相差26倍。快相占主导地位是由于铁氰化物对α链和β链氧化动力学存在较大差异（约5倍），而非血红素-血红素相互作用所致。这种实验方法似乎提供了一个明确的例子，说明在人血红蛋白脱氧四级结构中，两种亚基之间存在较大的动力学差异，且不受强协同效应的影响。
