细菌视紫红质多重突变体结构变化及其中间态的寿命  

Structure Change and Intermediate's Lifetime of Bacteriorhodopsin and Its Multipoint Mutants

作　　者：金卫华[1] 曹军卫[1] 王友亮[1] 熊贵光[2] 姚保利[3] 雷铭[3] 

机构地区：[1]武汉大学生命科学学院,武汉430072 [2]武汉大学物理科学与技术学院,武汉430072 [3]中国科学院西安光学精密机械研究所瞬态光学技术国家重点实验室,西安710086

出　　处：《高等学校化学学报》2007年第12期2321-2326,共6页Chemical Journal of Chinese Universities

基　　金：国家自然科学基金(批准号:60677038)资助

摘　　要：采用基因定点突变的方法,构建了细菌视紫红质(Bacteriorhodopsin,BR)的3种突变体蛋白,即单突变体BRE194Q、三突变体BRI119T/T121S/A126T和四突变体BRI119T/T121S/A126T/E194Q.测定了突变体和野生型BR在水溶液和聚乙烯醇(PVA)膜中的紫外-可见吸收光谱和拉曼光谱,采用显微视频录像技术记录了PVA膜中野生型和3个突变体样品的M态寿命.与野生型BR相比较,在水溶液中,单突变体的可见吸收光谱的最大吸收峰发生了轻微红移,三突变体和四突变体的最大吸收峰则分别发生了11.0和12.0 nm的明显蓝移.在PVA膜中,3个突变体BR的可见吸收光谱的最大吸收峰均发生蓝移,四突变体BR的最大吸收峰为557 nm,蓝移达15.0 nm.四突变体BR在水溶液中的共振拉曼光谱不仅表现有与M态特征相关的1567和1573 cm-1谱带,还有L态特征带1334 cm-1及N态特征带1200,1328,1530和1549 cm-1.在PVA膜中的样品与在水溶液中的比较,四突变体共振拉曼光谱的1334和1549 cm-1带消失,同时1187 cm-1带的强度下降.显微视频录像技术记录的PVA膜中样品的M态寿命表明,野生型BR的M态寿命最短,单突变体的M态寿命小于1.0 s,三突变体的寿命为3.0 s,四突变体的寿命为2.0 s.The site-specific residue replacements E194Q, Il19T/T121S/A126T and Ill9T/T121S/A126T/ E194Q were introduced into bop gene and expressed in halobacterium salinarium L33 with the vector pXL- NovR, respectively. The photoreaction of three mutants BRE194Q, BRI119T/T121S/AI26T and BRI119T/T121S/A126T/EI94Q （the quadruple mutant） of bacteriorhodopsin （BR） and WT-BR （ wild type BR） was investigated in solution and in PVA films at pH =7.0 by UV-Vis absorption spectrum and Resonance Raman spectra. The lifetime of M intermediate of the three mutants in PVA films were recorded by employing photomicrography. In distilled water, the visible absorption maximum of BRIII9T/TI21S/AI26T and BRIl19T/T121S/AI26T/EI94Q mutants were blue shifted notably by 11 and 12 nm respectively and the BRE194Q＇S was weakly red shifted in comparison with WT-BR. In PVA film, BRIIIgT/T1215/A126T/EI94Q mutant caused a blue shift of the visible absorption spectrum from 568 to 557 nm. The characteristic bands of Resonance Raman spectra of BRIl19T/T121S/A126T/EI94Q mutant were observed at 1334cm^-1 of the L intermediate, 1200, 1328, 1530 and 1549 cm^-1 of the N intermediate and 1567 and 1573 cm^-1 of M intermediate in solution. However, the 1334 and 1549 cm^-1 bands of the quadruple mutant disappeared and the intensity of 1187 cm6-1 band decreased in PVA film. The lifetime of M intermediate of BRE194Q was less than 1.0 s by photomicrography. The lifetime of M intermediates of BRI119T/TI21S/A126T and BRIllgT/T121S/A126T/E194Q were 3.0 s and 2.0 s, respectively.

关 键 词：细菌视紫红质 突变体 共振拉曼光谱 聚乙烯醇 

分 类 号：O62[理学—有机化学] Q632[理学—化学]