权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

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，局部的微小结构变化在空间上延伸到介观维度以实现生理功能，而蛋白质的高阶结构变化对于这一过程至关重要。肌红蛋白 (Mb) 是研究蛋白质此类特征的最佳分子之一，因为 CO 从碳单氧 Mb (MbCO) 中光解离是一种局域反应，在 50 fs 内发生，类似于量子产率几乎为 1 的阶跃函数。从X射线研究得知，在CO脱位后，铁原子移出卟啉平面约0.3 A，核心尺寸扩大0.05 A。为了探索这一过程中涉及的蛋白质动力学，我们研究了光解MbCO的皮秒时间分辨共振拉曼光谱。仔细检查1300-1650年CO光解后脱氧Mb的光谱 cm^<-1>区域显示卟啉环的核心尺寸扩展在仪器响应时间内（〜2 ps）完成。相比之下，Fe-His 拉伸模式 (VFe-His) 的强度和频率的变化发生在皮秒内，表明 Fe 从卟啉平面位移的时间演化相当可观。对于没有蛋白质基质的血红素组模型化合物也观察到相同的行为。因此，这反映了血红素本身的固有特性。另一方面，VFe-His模式的频率以〜100 ps的时间常数变化。对于没有蛋白质基质的模型化合物，没有观察到这种频率变化。因此，这一定是由蛋白质的三级结构变化引起的。 V_4 和 V_7 波段的反斯托克斯拉曼强度的时间变化表明，光解时立即产生振动激发血红素，并随后振动激发群体的衰变，时间常数分别为 1.1±0.6 和 1.9±0.6 ps。