Studies on Chemical Functions of Novel Redox Coenzymes

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In this research project, the physicochemical properties and chemical functions of novel redox coenzymes such as PQQ (pyrroloquinolinequinone) of bacterial alcohol and glucose dehydrogenases, TTQ (tryptophan tryptophylquinone) of bacterial amine dehydrogenases, and Tyr-Cys (a dimer of tyrosine and cysteine) of galactose oxidase have been explored. Followings are the summary of the results.PQQ Project・Model studies on quinoprotein methanol dehydrogenase has been carried out to find that the oxidation of methanol by calcium complex of coenzyme PQQ proceeds via addition-elimination mechanism. The catalytic role of calcium ion on the methanol oxidation has been also explored.・Catalysis by calcium ion on the reoxidation of reduced PQQ by molecular oxygen has been investigated.・Electrochemical behavior of coenzyme PQQ in aprotic organic media has been explored.・Photochemical oxidation of benzyl alcohols by the triplet excited state of coenzyme PQQ has been explored.・Photochemical redox react … More ions of coenzyme PQQ and related o-quinones have been investigated in detail.・Novel addition-cyclization reaction of nitroalkane anions with o-quinone derivatives has been found to proceed via electron transfer in the charge-transfer complexes.・TTQ Project・Model studies of TTQ-containing amine dehydrogenases has been performed to clarify the amine oxidation mechanism by TTQ coenzyme.・Electrostatic environment of the TTQ cofactor in methylamine dehydrogenase has been investigated by using TTQ model compounds.・Synthesis, physicochemical properties, and amine-oxidation reaction ofindolequinone derivatives as model compounds of novel organic cofactor TTQ of amine dehydrogenases have been investigated.Try-Cys Project・Active site models for galactose oxidase have been developed in order to shed light on the electronic effect of the thioether group in the novel organic cofactor.・Active site models for galactose oxidase have been developed in order to study the physicochemical properties and reactivities of copper (II) complex of the phenoxyl radical species of the novel organic cofactor. Less