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Light-Chemical Energy Conversion Study of Reconstituted Zinc-Protoporphyrin/Zinc- Carboxyphenylethynyl Porphyrin Myoglobin Mutants

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Light-Chemical Energy Conversion Study of Reconstituted Zinc-Protoporphyrin/Zinc- Carboxyphenylethynyl Porphyrin Myoglobin Mutants 國 立 交 通 大 學 生物科技研究所 碩士論文 利用重組鋅-原紫質及鋅-乙炔苯酸紫質 之不同肌紅蛋白突變株進行其光能轉化 學能的研究 Light-Chemical Energy Conversion Study of Reconstituted Zinc-Protoporphyrin/Zinc- Carboxyphenylethynyl Porphyrin Myoglobin Mutants 研究生：歐書涵 指導教授：吳東昆 博士 中華民國九十九年七月 利用重組鋅-原紫質及鋅-乙炔苯酸紫質之不同肌紅蛋白突變 株進行其光能轉化學能的研究 Light-Chemical Energy Conversion Study of Reconstituted Zinc-Protoporphyrin/Zinc- Carboxyphenylethynyl Porphyrin Myoglobin Mutants 研究生：歐書涵 Student: Shu-Han Ou 指導教授：吳東昆 博士 Advisor: Prof. Tung-Kung Wu Ph.D 國 立 交 通 大 學 生物科技研究所 碩士論文 A Manuscript of Dissertation Submitted to Department of Biological Science and Technology College of Biological Science and Technology National Chiao Tung University in partial Fulfillment of the Requirements for the Degree of Master of Philosophy in Biological Science and Technology Hsinchu, Taiwan, Republic of China July, 2010 中華民國九十九年七月 利用重組鋅-原紫質及鋅-乙炔苯酸紫質之不同肌紅蛋白突變 株進行其光能轉化學能的研究 中文摘要 經過定點突變的技術，可以將野生型肌紅蛋白 His-64、Val-68、Ile-107 分別 突變成 Asp、Leu、Met。研究指出，經突變的肌紅蛋白具有下列兩種特性：(1) 過氧化酶活性，(2) 能夠穩定帶有自由基的陽離子 (FeIV = O Por+‧)，進而延長電 荷分離的時間。肌紅蛋白的結構已經藉由高解析 X-ray 解出，且基本特性也已分 析完成，因此肌紅蛋白很適合用來當作電子轉移以及化學活性分析的模型。為了 將野生型及突變型肌紅蛋白(MbWT,MbH64D, MbV68L, MbI107M, MbH64D/V68L, MbH64D/V68L/I107M) 應用在以蛋白質為基礎的光-化學能量轉換的系統中及比較其 突變的影響，因此，我們將輔基團 鋅-原紫質 (ZnPP) 以及 鋅-乙炔苯酸紫質 (ZnPE1) 重組到肌紅蛋白內。藉由紫外光-可見光光譜及螢光光譜分析其生物物 理特性以確定輔基團成功地重組到蛋白質的活性中心，並藉此算出其能隙 (energy gap)。此外，我們也經由循環伏安法及微差脈衝伏安法求出重組金屬紫質 -肌紅蛋白複合體的 HOMO/LUMO 電位。在螢光生命期的比較中發現，將輔基 團重組到肌紅蛋白內的生命期比單獨輔基團溶解在四氫呋喃 (THF) 內還要長。 以蛋白質為基礎的光化學能量轉換的系統包含重組金屬紫質-肌紅蛋白複合體當 做感光酵素、三乙醇胺 (TEA) 當作電子提供者以及菸鹼胺腺呤雙核酸磷酸鹽 (NADP+) 當作電子接受者。比較不同輔基團以及突變點的重組金屬紫質-肌紅蛋 V68L + 白複合體中，ZnPE1-Mb 具有最好的 NADP 還原效率 (94.7%) 以及連續照光 6 小時的反應速率 (0.209 mM/hr)。 I Light-Chemical Energy Conversion Study of Reconstituted Zinc-Protoporphyrin/Zinc- Carboxyphenylethynyl Porphyrin Myoglobin Mutants Abstract After replacing His 64 with Asp, Val 68 with Leu, and Ilu 107 with Met of myoglobin (Mb) via molecular engineering, two properties exist: (1) peroxidase activity and (2) the ferryl porphyrin cation radical (FeIV = O Por+‧) stabilization for prolonging charge separation. Because the structure of myoglobin had been successfully solved by high-resolution x-ray crystallography and possess the characterization of availability, it is a suitable model to understand the electron-transfer (ET) reaction as well as the chemical reactivity. In order to apply these proteins into protein-based photo-chemical energy conversion system and compare the mutation effect, various Mb mutants, ranging from mono (MbH64D, MbV68L, MbI107M), double (MbH64D/V68L), and triple (MbH64D/V68L/I107M) mutations were reconstituted with prosthetic groups (ZnPP and ZnPE1) to generate metallo-porphyrin Mb complex. Biophysical properties characterization of the metallo-porphyrin Mb complexes, using UV-Vis and fluorescence spectrometry, validates the successful reconstitution of the prosthetic group inside the active site pocket and energy gap of the reconstituted metallo-porphyrin Mbs. Cyclic voltammetry and differential pulse voltammetry techniques further confirmed the HOMO/LUMO of the reconstituted metallo-porphyrin Mbs. In the picosecond fluorescence decays also showed apo-Mb reconstituted with porphyrin prolonged the lifetime compared with porphyrin in THF. The protein-based photo-chemical energy conversion systems were constructed, using II mutated apo-Mb reconstituted with different metalloporphyrin-derivatives as photosensitizers, triethanolamine (TEA) as electron donor and nicotinamide adenine dinucleotide phosphate (NADP+) as an electron acceptor. Among different reconstituted metalloporphyrin-Mbs in photoirradiation systems, MbV68L reconstituted with ZnPE1 exhibited the best energy conversion efficiency (94.7 %) and reaction rate within 6 hours photoirradiation (0.209 mM/hr), as comparable to that of the myoglobin reconstituted with ZnPP in photo-chemical energy conversion system. III 謝誌 (Acknowledgement) 經過了兩年的努力，終於如願以償拿到碩士學位。在這個過程中要感謝很多人 陪我ㄧ起度過。碩士班生涯中，最感謝的人莫過於指導教授- 吳東昆博士，在研 究方向以及觀念上的導正與指引，老師無不費煞苦心，殷殷指導，在此獻上我最 由衷的敬意。同時亦感謝 楊裕雄老師、李耀坤老師在百忙之中撥空參加學生的 口試以及審閱論文，並給予許多寶貴的意見與指正，使我的論文能夠更加完善。 此外，讓我能夠在兩年順利畢業，要特別感謝帶我的老大-晉豪學長。在他的 細心指導下，我不只學到了實驗的技術及應有的態度，在論文上也給予許多中肯 的建議。不管是在實驗上或是電腦方面有問題，老大總是會不厭其煩熱心地的給 予協助。小麵包學姊總是很有耐心教導我實驗，並且不吝於分享實驗「小撇步」； 不管什麼事情，她總是用認真嚴謹的態度去處理，我也期許自己能夠像她一樣。 感謝裕國學長在我研究感到困惑時，能夠給予建議，並且幫我建立自信心。感謝 程翔學長提供不同種類的早餐，讓我不再天天都吃宿舍樓下的摩斯和全家；當我 實驗遇到瓶頸的時候，學長總是會扮演「心靈導師」的腳色，幫我做好「心理輔 導」，讓我更有動力地繼續下去。媛婷學姊獨有的思考能力，帶給實驗室不凡的 效率與嚴謹，足以讓學弟妹以此為楷模。晉源學長對待事情樂觀的態度，讓我不 再畏懼眼前面臨的困難。小紅學姊總是懷抱著開朗的心情，讓整個實驗室充滿著 愉悅的氣氛。文鴻學長嘗試以幽默的態度教導我在實驗上的最基本原則，讓我明 瞭培養好奇心與求知慾是一切研究的骨架;感謝學長給予包容與耐心，指導著一 點一滴成長的我。感謝Allen學長像個家庭醫師一樣，可以提供免費的問診以及 醫學相關知識。感謝Mili學姊的好手藝，讓我品嘗到道地的印度料理也讓我的英 文會話有一點進步。感謝已畢業的學長姐，宏城學長、宏明學長、小妹學姊、天 昶學長在生活上以及實驗上的幫忙。感謝碩士班一起打拚的同學們，靜婷、小 花、 奕齊，在這一段學習的過程中，有你們在旁邊加油打氣互相勉勵，與你們相處的 時光讓我受益良多。學弟妹世穎、欣芳、欣怡、怡臻、富生、孟兒、欣樺、婉婷、 幫忙分擔實驗室公共事務，有你們在的實驗室格外溫馨，雖然你們還在累積研究 上的經歷，但我特別感謝你們對實驗室的付出與照顧，我衷心期盼未來的你們能 成為學弟妹的典範。感謝專題生孟儒、俞靜、小彥、聖為、奕汝、瑛婷、家嘉， 有你們的加入，實驗室多了一份難能可貴的稚氣，調和大家在實驗之虞的緊繃氣 氛。感謝林敬堯老師實驗室成員幫忙合成ZnPE1化合物；感謝德茹學姊、翊暐撥 空幫忙量測樣品的半生期。 最後，我要感謝我的家人，爸爸、媽媽、小阿姨一家人，因為有你們的支持與 鼓勵，讓我可以無後顧之憂的專心於課業上，順利地走過碩士班兩年的日子。碩 士班生涯已經告一段落，往後的日子又是另一個開始，我會帶著老師們的教誨與 各位的祝福，勇敢面對挑戰。 IV Table of Contents 中文摘要 ....................................................................................................................... I Abstract ........................................................................................................................ II 謝誌 (Acknowledgement) ........................................................................................ IV Table of Contents ........................................................................................................ V Table of Figures...................................................................................................... VIII Table of Tables ....................................................................................................... XIII 1. Introduction .......................................................................................................... 1 1.1 THE ENERGY ISSUE .......................................................................................... 1 1.2 PHOTOSYNTHESIS ........................................................................................... 2 1.3 ARTIFICIAL PHOTOSYNTHESIS ......................................................................... 6 1.4 PORPHYRIN ..................................................................................................... 8 1.5 AGGREGATION FORMS OF PORPHYRIN ........................................................... 10 1.5.1 H-aggregate .............................................................................................. 11 1.5.2 J-aggregate ............................................................................................... 14 1.6 MYOGLOBIN ................................................................................................. 17 1.6.1 Structure of myoglobin ............................................................................ 17 1.6.2 Molecular engineering of myoglobin ....................................................... 19 1.6.3 The application of myoglobin in electron transfer study ......................... 21 1.7 PHOTOTRIGGERED CHEMICAL REDUCTION OF RECONSTITUTED ZINC PORPHYRIN MYOGLOBIN ............................................................................... 25 1.8 DYE-SENSITIZED SOLAR CELL ....................................................................... 26 V 2. Specific aims ....................................................................................................... 29 2.1 RECONSTITUTION OF APO-MYOGLOBIN WITH METALLO-PORPHYRINS............ 29 2.2 OPTIC PROPERTIES OF RECONSTITUTED METALLO-PORPHYRIN-MYOGLOBIN (UV-VIS, FLUORESCENCE, AND TCSPC) ....................................................... 30 2.3 ELECTROCHEMISTRY ANALYSIS (CYCLIC VOLTAMMETRY ANALYSIS (CV) AND DIFFERENTIAL PULSE VOLTAMMETRY (DPV))................................................ 30 2.4 THE LIGHT-CHEMICAL ENERGY CONVERSION ANALYSIS PHOTOIRRADIATION ASSAY ........................................................................................................... 31 3. Experimental materials and procedures .......................................................... 32 3.1 EXPERIMENTAL MATERIALS ........................................................................... 32 3.2 EXPERIMENTAL APPARATUS ........................................................................... 33 3.3 PURIFICATION OF MUTATED MYOGLOBIN AND EXTRACTION OF REMAINED HEME BY METHYL ETHYLKETONE METHOD ................................................... 33 3.4 RECONSTITUTION OF APO-MYOGLOBIN WITH ZNPP AND ZNPE1 ................... 34 3.4.1 Reconstitution of apo-myoglobin with ZnPP .......................................... 34 3.4.2 Reconstitution of apo-myoglobin with ZnPE1 ......................................... 35 3.5 CIRCULAR DICHROISM (CD) SPECTROSCOPOLARIMETRY .............................. 35 3.6 PICOSECOND FLUORESCENCE DECAYS ........................................................... 35 3.7 CYCLIC VOLTAMMETRY ANALYSIS ................................................................. 36 3.8 PHOTOIRRADIATION EXPERIMENT ................................................................. 36 4. Results and discussion ....................................................................................... 38 4.1 PURIFICATION OF APO-MYOGLOBIN MUTANTS ............................................... 38 4.2 UV-VIS ANALYSIS RESULTS OF RECONSTITUTED METALLO-PORPHYRIN-MBS 39 4.3 CIRCULAR DICHROISM (CD) SPECTROPOLARIMETRY ...................................
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