Soni S K, Kiesow L A
Biochemistry. 1977 Mar 22;16(6):1165-70. doi: 10.1021/bi00625a021.
The transition from deoxy to oxystructure of hemoglobin A (Hb) is accompanied by the breaking of the salt bridges formed by C-terminal residues in deoxy-Hb. This, in turn, changes the state of the heme. The switch between these different allosteric forms can be followed by changes in the optical absorbance spectra (Perutz, M. F., Ladner, J. E., Simon, S. R., and Ho, C. (1974), Biochemistry 13, 2163). Using difference spectroscopy in the soret region, pH-dependent spectral changes of Hb and its derivatives (carbamylated at both the alpha-NH2 groups, alpha2cbeta2c; N-ethylsuccinimide hemoglobin, NES-Hb) in their deoxy and carbonmonoxy forms were measured. From these measurements, the pK values of histidine-146beta and valine-1alpha in deoxy-Hb were determined to be 8.6 +/- 0.2 and 7.7 +/- 0.1, respectively. In carbonmonoxy-Hb a pK value of 6.3 +/- 0.1 was found.
血红蛋白A（Hb）从脱氧结构向氧合结构的转变伴随着脱氧Hb中由C末端残基形成的盐桥的断裂。这进而改变了血红素的状态。这些不同变构形式之间的转换可以通过光吸收光谱的变化来跟踪（佩鲁茨，M.F.，拉德纳，J.E.，西蒙，S.R.，和何，C.（1974年），《生物化学》13，2163）。使用索雷特区域的差示光谱法，测量了Hb及其衍生物（α-NH2基团均被氨甲酰化，α2cbeta2c；N-乙基琥珀酰亚胺血红蛋白，NES-Hb）在脱氧和一氧化碳结合形式下的pH依赖性光谱变化。通过这些测量，确定脱氧Hb中组氨酸-146β和缬氨酸-1α的pK值分别为8.6±0.2和7.7±0.1。在一氧化碳结合Hb中发现pK值为6.3±0.1。
