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

新型氨基酸衍生氧化还原活性辅助因子的化学功能：我们长期以来的研究活动之一是合成和表征新发现的有机辅助因子，如细菌醇脱氢酶的吡罗喹啉醌（PQQ），胺脱氢酶的色氨酸色氨酸醌（TTQ）和半胱氨酸色氨酸醌（CTQ），半乳糖氧化酶的酪氨酸-半胱氨酸辅助因子（Tyr-Cys）。本研究的主要工作是探索CTQ和tyrr - cys辅助因子的氧化还原功能和反应机制以及翻译后修饰途径。此外，对金属离子对有机辅因子氧化还原活性的影响也进行了大量的研究。结果表明，tyrr - cys辅助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与过渡金属离子的相互作用控制，这为进一步了解酶促氧化还原反应的机制提供了重要的见解。为了检验有机辅助因子的化学性质和功能，还开发了CTQ辅助因子的模型化合物。氧化还原性质和有机自由基配合物的功能：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）的模型化合物的开发。研究了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、理化性质和催化活性，揭示了其在核糖核苷酸还原酶（RNR）、光系统II （PSII）、前列腺素合成酶等方面的生物学功能。例如，用2,4-二叔丁基苯酚与叠氮冠醚、2,4-二叔丁基-6-（1,4,7,10-四氧基-13-叠氮-环戊基-13-甲基）苯酚和2,4-二叔丁基-6-（1,4,7,10,13-五氧基-16-叠氮-环十八基-16-甲基）苯酚连接，制备了一系列碱土金属离子的酚酸和苯氧基自由基配合物以及一价和二价阳离子。这样做是为了检查阳离子对结构的影响，物理化学性质和苯酚和苯氧基配合物的氧化还原反应性

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