以時間解析紅外差異吸收光譜法結合數學的相關性分析方法研究細菌視紫質光迴圈的質子傳遞過程與結構變化

Correlation Analyses of the Time-evolved Infrared Features of the Bacteriorhodopsin Photocycle

顏邦廷(Bang-Ting Yan)

指導教授 ： 朱立岡

國立清華大學/理學院/化學系/碩士(2015年)

摘要

吾人以時間解析傅氏紅外光譜儀研究細菌視紫質的光迴圈行為，並由紅外差異吸收光譜中挑選出12支特徵吸收峰，將其時間側寫以相關性方法進行分析，繪製出數個時間區段內的相關性等高線圖。藉由觀察等高線圖之中相關性反轉，分析光迴圈中的動力學行為受到驅動力影響的強度及時序，其結果與前人對光迴圈中間態演進的研究吻合。吾人希望提供一個不需要建立中間態以及整體指數擬合分析的方法，直接由吸收峰之間隨時間變化的關聯性，獲得光迴圈中質子傳遞過程的動力學資訊。

關鍵字

時間解析紅外差異吸收光譜 ； 細菌視紫質 ； 差異吸收 ； 相關性等高線圖

並列摘要

A step-scan Fourier-transform interferometer was employed to collect the time-evolved difference infrared spectra of bacteriorhodopsin upon photoexcitation. Without a kinetics model being established or target analysis to extract the difference spectra of the intermediates in the conventional photocycle, correlation analysis of the infrared features was used to examine the evolution of the interactive strengths between the retinal Schiff base and its proton donor and acceptor in different periods of the photocycle. Following the evolution of the correlation, those correlative characteristics satisfactorily coincided with the transitions of M  N, N  O, and O  bR. We therefore have illustrated the trajectory of the driving forces on the localized molecular moieties during the photocycle: proton acceptor Asp85 (1762 and 1755 cm–1) → proton donor Asp96 (1400 cm–1) → C–C stretch of 13-cis retinal (1186 cm–1) → C14=C15 stretch of all-trans retinal (1506 cm–1) → C10–C11 stretch of all-trans retinal (1168 cm–1). The correlation analysis successfully provided the dynamic and local conformational alterations as the bR photocycle evolved, without the need to establish a kinetics model, introduce discrete intermediates, or use deconvolution algebra. Including more bands in the correlation analysis provides more thorough information of the structural alteration of the photocycle. The combination of the time-resolved infrared spectroscopic method and the correlation analysis could be a promising method of illustrating the photochemistry of photosynthetic proteins at the molecular level.

並列關鍵字

time-resolved Fourier transform infrared spectroscopy ； bacteriorhodopsin ； difference absorbance ； correlation contour

參考文獻

[83] Christian, Z.; Ramona, S.; Jorg, T.; Dieter, O.; Joachim, H. Proc. Natl. Acad. Sci. U.S.A. 1999, 96, 5498−5503.

[10] Eisfeld, W.; Pusch, C.; Diller, R.; Lohrmann, R.; Stockburger, M. Biochemistry 1993, 32, 7196−7215.

[19] Baudry, J.; Tajkhorshid, E.; Molnar, F.; Phillips, J.; Schulten, K. J. Phys. Chem. B 2001, 105, 905−918.

[1] Oesterhelt, D.; Stoeckenius, W. Proc. Nat. Acad. Sci. U. S. A. 1973, 70, 2853−2857.

[4] Stoeckenius, W.; Rowen, R. J. Cell Biol. 1967, 34, 365−393.