Bacteriorhodopsin (bR)為Halobacterium salinarium嗜鹽菌紫色細胞膜(puple membrane，PM)上的獨一光驅動質子泵之光能轉換蛋白。本研究以比色管光電系統證明在開光(light-on)及關光(light-off)情況下，PM溶液分別會有氫離子釋出與吸收的光循環泵機制。

首先，針對PM溶液連續以光激發30分鐘前後，量測系統中工作槽與相對槽溶液之pH值變化，來推測中間介質銅片上兩面的物理及化學反應。以XPS (X-ray photoelectron spectroscopy、SEM (Scanning electron microscopy)及XRD (X-ray diffraction)分析發現，連續照光讓兩邊銅面上產生氧化還原反應，會於相對槽銅面生成氧化亞銅(Cu2O)，後續再利用此被氧化的銅面當工作銅面與PM溶液接觸，便會造成整個系統迴路上光電流強度的大幅增加。

接著，分別針對原生株(native)和重組突變株(wild-type、G241C、D96N)所產生之PM溶液，其light-on、light-off時所產生光電流的應答作一比較。結果發現連續受光激發後的各PM溶液較未受激發的溶液，其光電流值會增強，並在light-on或light-off的主訊號之後，會尾隨連續出現多個小電流的訊號，且其強度會較新鮮的各PM溶液強。

最後，藉以改變光入射頻率以及外在環境之pH值，比較native、wild-type、G241C、D96N PM光電流訊號之差別。發現D96N可以在比其餘PM溶液更高的光頻率下，還有光電流應答產生；關於pH值方面，D96N PM會比native和wild-type PM在酸性或鹼性下，更早轉換成藍膜(BRblue)與鹼膜(BRa)，而G241C PM次之，native及wild-type PM維持在紫色的pH範圍較廣。

Bacteriorhodopsin (bR), the only protein in the purple membrane (PM) of Halobacterium salinarium, is a light-driven proton pump. To verify the release and uptake of protons in the light-on and light-off photocycle, respectively, of an illuminated PM solution, a cuvette photoelectric system was set up to trace the photocurrent arising from proton pumping.

First, the role of the copper-plate medium in the photoelectric system and the reactions taking place on its both sides while the PM solution was continuously illuminated for 30 min were revealed by monitoring the pHs of the solutions facing either side (the working and counter parts). We analyzed by XPS (X-ray photoelectron spectroscopy, SEM (Scanning electron microscopy) and XRD (X-ray diffraction), and suggested that the continuous illumination induced the oxidation of the counter-copper plate. Then we used the counter-copper plate as the working-copper plate to contact with PM solutions. This resulted in the enhancement of the photoelectric signals in the following experiments.

Secondly, the photoelectric signals, light-on and light-off, of the illuminated solutions of native, wild-type, G241C, and D96N PMs were each detected and compared. The results showed that the photoelectric peak signals arisen from continuously illuminated PM solutions were higher and accompanied by more after-peaks than those from the fresh solutions.

Finally, we compared the native, wild-type, G241C and D96N PM by change the frequency of excited light and the surrounding pH. We found that D96N PM could still yield photoelectric response at higher frequency. About the pH, D96N PM changed from BR to BRblue and BRa easier than native and wild-type PM and the following was G241C PM. The color of native and wild-type PM maintained as purple at wider pH range.

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