Time-Resolved Vibrational Spectroscopic Investigation of Ultrafast Protein Dynamics Coupled with Photoreaction

超快蛋白质动力学与光反应耦合的时间分辨振动光谱研究

基本信息

批准号：
12045264
负责人：
KITAGAWA Teizo
金额：
$ 9.09万
依托单位：
Center for Integrative Bioscience, Okazaki National Research Institutes
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research on Priority Areas
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

项目摘要

In many biological systems a localized small structural change extends spatially to mesoscopic dimensions to achieve a physiological function, and higher-order structural changes of proteins are essential to this process. Myoglobin (Mb) is one of the best molecules for studying such features of proteins, because photodissociation of CO from carbonmonoxyMb (MbCO), a localized reaction, takes place within 50 fs like a step-function with a quantum yield of nearly unity. It is know from x-ray studies that the iron atom moves out of the porphyrin plane by 〜0.3 A and the core-size expands by 0.05A upon deligation of CO. To explore the protein dynamics involved in this process, we have investigated picosecond time-resolved resonance Raman spectra of photodissociated MbCO.Close inspection of the spectra of deoxyMb following CO photolysis in the 1300-1650 cm^<-1> region revealed that the core-size expansion of porphyrin ring is completed within the instrumental response time (〜2 ps). In contrast, changes in the intensity and frequency of the Fe-His stretching mode (VFe-His) occurred in picoseconds, suggesting appreciable time evolution for the Fe displacement from the porphyrin plane. The same behaviors were observed for the model compound of the heme group without protein matrix. Therefore, this reflects an intrinsic property of heme itself. On the other hand, the frequency of the VFe-His mode changed with a time constant of 〜100 ps. This frequency change was not seen for the model compound without the protein matrix. Therefore, this must be caused by tertiary structural changes of the protein. Temporal changes of the anti-Stokes Raman intensity of the V_4 and V_7 bands demonstrated immediate generation of the vibrationally excited heme upon photolysis and subsequent decay of the vibrationally excited population with the time constants of 1.1±0.6 and 1.9±0.6 ps, respectively.

在许多生物系统中，局部的小结构变化频繁扩展到介镜维度以实现身体功能，而蛋白质的高阶结构变化对于此过程至关重要。肌红蛋白（MB）是研究蛋白质此类特征的最佳分子之一，因为从碳舒张蛋白（MBCO）的CO进行了局部反应的co的光解异位，发生在50 fs之内，例如具有几乎统一的量子产率的步进功能。 It is known from x-ray studies that the iron atom moves out of the porphyrin plane by ~0.3 A and the core-size expands by 0.05A upon determination of CO. To explore the protein dynamics involved in this process, we have investigated picosecond time-resolved resonance Raman spectra of photodissociated MbCO.Close inspection of the spectra of deoxyMb following CO photolysis in the 1300-1650 CM^<-1>区域显示，卟啉环的核心大小膨胀在仪器响应时间（〜2 ps）内完成。相比之下，Fe-His伸展模式的强度和频率（VFE-HIS）发生的变化发生在Picseconds中，这表明从卟啉平面的Fe位移有明显的时间演变。对于没有蛋白质基质的血红素组的模型化合物，观察到相同的行为。因此，这反映了血红素本身的内在特性。另一方面，VFE-HIS模式的频率随时间常数〜100 ps变化。没有蛋白质基质的模型化合物看不到这种频率变化。因此，这必须是由蛋白质的三级结构变化引起的。 V_4和V_7频段的反stokes拉曼强度的时间变化表明，在光解和随后的几乎令人兴奋的种群的衰减后，几乎激发的血红素的时间变化，分别为1.1±0.6和1.9±0.6 ps。