Electron-Transfer Reactions of Chemically Modified Hemoproteins and Their Model Compounds

1)二亚乙三胺五乙酸(MetMbDTPA)修饰的高铁肌红蛋白(MetMbDTPA)分别与铜(II)和钴(II)结合形成metMb{Cu^&lt；ii&gt；(DTPA)}和metMb{Co^&lt；ii&gt；(DTPA)}。后者被K_3[Fe(CN)_6]进一步氧化生成metMb{Co^&lt；III&gt；(DTPA)}。用电子自旋共振、原子吸收光谱和循环伏安法对这些化合物进行了表征。2)用分光光度法研究了单电子还原脱氧分子Mb{Co^&lt；III&gt；(DTPA)}在分子内和分子间的电子转移反应。分子内的电子转移反应取决于DTPA的键合位置。3)用锌(II)离子取代了MetMbDTPA的血红素铁，结合的铜(II)离子有效地猝灭了其激发的单重态和三重态。3)合成并表征了紫精或喹啉偶联的N-烷基卟啉二元化合物。研究了在乙腈和丙二醇中，位向和距离对猝灭和光致电子转移反应速率的影响。紫精或喹啉离子与卟啉平面的垂直取向减慢了电子和能量转移反应的速度。5)研究了手性紫精自由基阳离子与血红蛋白之间的立体选择性电子转移反应。手性紫精的(S，S)-异构体优先还原高铁肌红蛋白和细胞色素c。

1) Metmyoglobin modified with diethylenetriaminepentaacetic acid (metMbDTPA) binds Cu(II) and Co(II) to form metMb{Cu^<II>(dtpa)} and metMb{Co^<II>(dtpa)}, respectively. The latter was further oxidized by K_3[Fe(CN)_6] to form metMb{Co^<III>(dtpa)}. These compounds were characterized by an ESR and an atomic absorption spectro-scopies and a cyclic voltammetry. 2) The intra- and intermolecular electron-transfer reactions of one electron-reduced deoxyMb{Co^<III>(dtpa)} were investigated by spectrophotometrically. The intramolecular electron-transfer reaction depends on the attached site of DTPA.3) The heme iron of metMbDTPA was replaced by a Zn(II) ion and the excited singlet and triplet states of ZnMbDTPA were efficiently quenched by a bound Cu(II) ion. The excited triplet state of ZnMbDTPA was also quenched intramolecularly by the oxidized form of cytochrome c. 4) Viologen or quinoliniumlinked N-alkylporphyrin dyads were synthesized and characterized. The orientation and distance effects on the rates of the quenching and photo-induced electron-transfer reactions were investigated in acetonitrile and propylene glycol. Orthogonal orientation of viologen or quinolinium ion against the porphyrin plane decelerated the electron- and energy-transfer reaction rates. 5) The stereoselective electron-transfer reactions between hemoproteins and chiral viologen-radical cations were investigated. The (S,S) -isomers of chiral viologens preferentially reduced metmyoglobin and cytochrome c.