以捲曲螺旋胜肽鏈建構銅活性中心之合成與反應性探討

Assembly of Type II Copper Center in α-Helical Coiled-Coil

盧培中(Pei-Chung Lu)

指導教授 ： 魯才德

中原大學/理學院/化學研究所/碩士(2015年)

https://doi.org/10.6840/cycu201500646

摘要

本研究是以固相胜肽合成法(SPPS)，合成具不同序列之胜肽鏈，並且進一步探討胜肽鏈形成捲曲螺旋結構的條件。本研究成功的利用從頭設計胜肽的方式合成出一系列的胜肽序列G-(EXAAYKZ)n-GYG (X=I、H、E，Y=L、H，Z=Q、K、W)，利用圓二色光譜(circular dichroism spectrum)鑑定胜肽序列的二級結構，進一步利用具捲曲螺旋結構的H1a@H4 (G-EHAALKQ-EIAALKK-EIAALKW-EIAALKQ-GYG)，架構順磁含銅及逆磁含鋅之金屬中心。
研究結果發現，Cu2+與H1a@H4是以1：2的方式存在，也透過NMR、EPR、ESEEM和EXAFS鑑定Cu:(H1a@H4)2的中心金屬結構與配位環境，其配位環境為type II copper center，銅離子以四配位的方式鍵結形成平面四邊形的形式存在，即(H1a@H4)2是以Glu和His去配位銅離子。
之後進一步利用所架構出的Cu:(H1a@H4)2與還原劑反應，發現ascobic acid和dithionite能夠有效地將CuII:(H1a@H4)2的中心金屬還原成CuI:(H1a@H4)2；而CuI:(H1a@H4)2則可與O2反應轉換回CuII:(H1a@H4)2的形式，確定Cu:(H1a@H4)2中Cu具氧化還原特性，進一步利用此氧化還原特性輔助有機化合物的轉換仍須後續探討。

關鍵字

胜肽

並列摘要

Various peptide were synthesized by “ Solid Phase Peptide Synthesis ” (SPPS). Successfully, using a de novo designed peptide prepared series of coiled coil peptides (G-(EXAAYKZ)n-GYG (X=I、H、E，Y=L、H，Z=Q、K、W)) based on the heptad repeat approach to study copper enzymes. H1a@H4 was helix bundle conformation based on circular dichroism (CD) spectrum. H1a@H4 used that metals form strong interactions with the side chains of residues such as His, to binding with Cu(II) and Zn(II).
H1a@H4 binding Cu(II) with a 1:1metal:dimer ratio. Then Cu:(H1a@H4)2 which was characterized by NMR、EPR、ESEEM and EXAFS. The activity site of Cu:(H1a@H4)2 was type II copper center, and the coordination geometry of Cu(II), distorted square planar. Cu:(H1a@H4)2 reaction with ascorbic acid and dithionite, that can reduce CuII:(H1a@H4)2 to CuI:(H1a@H4)2. Then Cu:(H1a@H4)2 reacted with some substrates ( fluorene、styrene、xanthene、9,10-dihydroanthracene、cyclhexanol、1-phenylethanol ), to test Cu:(H1a@H4)2 had any catalase reactivity. The results Cu:(H1a@H4)2 features O2-reductase reactivity and catalase reactivity of H2O2.

並列關鍵字

α-Helical Coiled-Coil

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