新規な複素環オルトキノン系補欠分子の化学的機能と応用

抄録

The chemical functions of novel heterocyclic o-quinone cofactors, PQQ (pyrroloquinolinequinone) and TTQ (tryptophan tryptophylquinone), and their derivatives were investigated from the viewpoints of synthetic organic chemistry. PQQ was found to be a good catalyst in the aerobic oxidation of biologically important substances such as amines, amino acids, thiols, glucose, NADH, and so on. Studies on the structure-reactivity relationships and product analyses provided a lot of important information on the structural importance of PQQ and on the oxidation reaction mechanisms. In particular, the reaction of PQQ and methanol was examined in detail to suggest that the enzymatic oxidation of methanol proceeds via an ionic mechanism through the C-4 acetal intermediate. PQQ and its related compounds were also found to act as an efficient mediator in the electrochemical oxidation of NADH and the electrochemical reduction of O₂, which could be coupled with enzymatic redox reactions. An efficient enzymatic redox reaction in organic solvents was also constructed by applying PQQ as an electron transfer catalyst. The model compound of the newly found cofactor TTQ was synthesized for the first time and its physicochemical properties and chemical functions were found to be very close to those of the native enzyme.