Yang Ning-li, Zhang Shu-yi, Sun Li, Qu Min, Shui Xiu-ji, Chen Hui-lan
Laboratory of Modern Acoustics, Institute of Acoustics, Nanjing University, Nanjing 210093, PR China.
Ultrasonics. 2006 Dec 22;44 Suppl 1:e1233-7. doi: 10.1016/j.ultras.2006.05.075. Epub 2006 Jun 5.
Enthalpy and conformational volume changes induced by laser photo-dissociation reactions of mammalian oxy-hemoglobin, such as human, bovine, pig, horse and rabbit oxy-hemoglobins, are investigated by pulsed photoacoustic calorimetry. Generally, the response time of the photoacoustic calorimetry is restricted by the width of the laser pulse and the bandwidth of the acoustic detector. Considering the time window of the experimental system, the enthalpy and conformational volume changes detected should be caused by the tertiary relaxation of the heme proteins. In order to calculate the enthalpy and conformational volume changes, the quantum yields of the photo-dissociation products of oxy-hemoglobins must be measured and taken into account. Finally, the enthalpy and conformational volume changes of the oxy-hemoglobins connected with the tertiary relaxation are obtained, which show that for all measured mammalian oxy-hemoglobins the values of enthalpy changes are in the range of 30.0-46.8 kcal/mol and volume changes are of 2.3-7.8 ml/mol although the quantum yields for the different species may have much bigger differences. A possible explanation of the results is presented.
通过脉冲光声量热法研究了哺乳动物氧合血红蛋白（如人、牛、猪、马和兔的氧合血红蛋白）激光光解离反应引起的焓变和构象体积变化。一般来说，光声量热法的响应时间受激光脉冲宽度和声探测器带宽的限制。考虑到实验系统的时间窗口，检测到的焓变和构象体积变化应由血红素蛋白的三级弛豫引起。为了计算焓变和构象体积变化，必须测量并考虑氧合血红蛋白光解离产物的量子产率。最后，得到了与三级弛豫相关的氧合血红蛋白的焓变和构象体积变化，结果表明，对于所有测量的哺乳动物氧合血红蛋白，焓变值在30.0 - 46.8千卡/摩尔范围内，体积变化为2.3 - 7.8毫升/摩尔，尽管不同物种的量子产率可能有更大差异。文中给出了对结果的一种可能解释。
