Ilari A, Boffi A, Chiancone E
Department of Biochemical Sciences, A. Rossi Fanelli, University La Sapienza, Rome, Italy.
Arch Biochem Biophys. 1995 Jan 10;316(1):378-84. doi: 10.1006/abbi.1995.1050.
The Soret spectra of the dimeric hemoglobin from Scapharca and of horse myoglobin reconstituted with protoporphyrin IX and Zn-protoporphyrin IX have been measured over the range 290-80 K. With increase in temperature the Soret band broadens and shifts to a different extent depending on the protein and the presence of the metal. In the Zn-protoporphyrin IX derivatives the spectral changes are more marked in myoglobin than in the dimeric hemoglobin. In the protoporphyrin IX derivatives, in which the spectral changes are significantly reduced, the opposite is true. The data have been analyzed in terms of coupling of the protein low-frequency vibrational motions to the porphyrin electronic transition (V. Srajer et al., 1986, Phys. Rev. Lett. 57, 1267-1270; A. Di Pace et al., 1992, Biophys. J. 63, 475-484). The analysis indicates that the heme pocket of the dimeric hemoglobin is characterized by an unusual rigidity and that the metal plays a different role in the transmission of the protein motions to the heme moiety in the dimeric hemoglobin and in myoglobin. Static and dynamic fluorescence measurements carried out at room temperature are in line with these conclusions.
在290 - 80K范围内测量了紫贻贝二聚体血红蛋白以及用原卟啉IX和锌原卟啉IX重构的马肌红蛋白的索雷特光谱。随着温度升高，索雷特带变宽并根据蛋白质和金属的存在情况发生不同程度的移动。在锌原卟啉IX衍生物中，肌红蛋白的光谱变化比二聚体血红蛋白更明显。在原卟啉IX衍生物中，光谱变化显著减小，情况则相反。已根据蛋白质低频振动运动与卟啉电子跃迁的耦合对数据进行了分析（V. Srajer等人，1986年，《物理评论快报》57卷，1267 - 1270页；A. Di Pace等人，1992年，《生物物理杂志》63卷，475 - 484页）。分析表明，二聚体血红蛋白的血红素口袋具有异常的刚性，并且金属在二聚体血红蛋白和肌红蛋白中将蛋白质运动传递到血红素部分的过程中发挥着不同的作用。在室温下进行的静态和动态荧光测量与这些结论一致。
