Chemical Functions of Novel Organic Cofactors Derived from Amino Acids by Post-translational Modification

新型氨基酸衍生的氧化还原活性辅因子的化学功能：我们长期的研究活动之一涉及新发现的有机辅因子的合成和表征，如细菌醇脱氢酶的吡咯喹啉醌（PQQ），胺脱氢酶的色氨酸-半胱氨酸-半胱氨酸-醌（TTQ）和半乳糖氧化酶的酪氨酸-半胱氨酸辅因子（Tyr-Cys）。本研究的主要工作是探索CTQ和Tyr-Cys辅因子的氧化还原功能、反应机制以及翻译后修饰途径。此外，大量的努力已经集中在金属离子对有机辅因子的氧化还原反应性的影响的检查。作为结果，我们发现Tyr-Cys辅因子模型化合物的氧化还原活性和稳定性在很大程度上受到与过渡金属离子的相互作用的控制，这为研究Tyr-Cys辅因子模型化合物的氧化还原活性和稳定性提供了重要的见解。 ...更多信息 酶促氧化还原反应的机理。CTQ辅因子的模型化合物也已经开发，以检查有机辅因子的化学性质和功能有机自由基复合物的氧化还原性质和功能：我们的主要注意力集中在生物相关的有机自由基，如苯氧基自由基和半醌自由基的模型化合物的发展。本文通过对有机自由基的电子结构、氧化还原活性及其金属配合物的结构、物理化学性质和催化活性的研究，揭示了有机自由基在RNR中的生物学功能（核糖核苷酸还原酶），PSII（光系统II）、前列腺素合酶等。例如，以2，4-二叔丁基苯酚与氮杂冠醚、2，4-二叔丁基-6-（1，4，7，10-四氧杂-13-氮杂-环十五碳-13-基甲基）苯酚和2，4-二叔丁基-6-（1，4，7，10，13-五氧杂-16-氮杂-环十八碳-16-基甲基）苯酚。这样做是为了研究阳离子对酚盐和苯氧基自由基复合物的结构、物理化学性质和氧化还原反应性的影响。

Chemical Functions of Novel Amino Acid Derived Redox-Active Cofactors: One of our longstanding research activities involves synthesis and characterization of newly found organic cofactors such as pyrroloquinolinequinone (PQQ) of bacterial alcohol dehydrogenases, tryptophan tryptophylquinone (TTQ) and cysteine tryptophylquinone (CTQ) of amine dehydrogenases, and tyrosine-cysteine cofactor (Tyr-Cys) of galactose oxidase. The main efforts of this study have been directed toward exploration of redox functions and the reaction mechanism as well as the post-translational modification pathways of CTQ and Tyr-Cys cofactors. In addition, great deals of efforts have been focused on the examination of metal ion effects on the redox reactivity of the organic cofactors. As the results, we have found that the redox activity and stability of the Tyr-Cys cofactor model compounds are largely controlled by the interaction with transition-metal ions, providing siginificantly important insights into the m … More echanism of enzymatic redox reactions. Model compounds of CTQ cofactor have also been developed in order to examine the chemical properties and functions of the organic cofactorRedox Properties and Functions of Organic Radical Complexes: Our main attention has focused on the development of model compounds of biologically relevant organic radicals such as phenoxyl radicals and semiquinone radicals. Electronic structures and redox reactivity of the organic radicals as well as the structure, physicochemical properties, and catalytic activities of their metal complexes have been investigated to shed light on biological functions of such species in RNR (ribonucleotide reductase), PSII (photosystem II), prostaglandin synthase, and so on. For example, phenolate and phenoxyl radical complexes of a series of alkaline earth metal ions as well as the monovalent and divalent cations have been prepared using 2,4-di-tert-butylphenol connected to aza-crown ethers, 2,4-di-tert-butyl-6-(1,4,7,10-tetraoxa-13-aza-cyclopentadec-13-ylmethyl) phenol and 2,4-di-tert-buty1-6-(1,4,7,10,13-pentaoxa-16-aza-cyclooctadec-16-ylmethyl) phenol. This was done to examine the effects of the cations on the structure, physicochemical properties and redox reactivity of the phenolate and phenoxyl radical complexes Less