Isolation and identification of N-carbamoyl-beta-D-glucopyranosylamine from human serum.

N-carbamoyl-beta-D-glucopyranosylamine (NCG) is a compound, which can chemically be synthesized by the condensation of glucose and urea by heating under acidic condition. In this study, we isolated and identified NCG and its anomer from human serum. This is the first study showing the occurrence and isolation of NCG from a natural source. The NCG level in human serum was estimated to be 71+/-33 microM using a glucose-3-dehydrogenase-based assay. Because NCG is not commercially used in foods or drugs, we conclude that the NCG isolated from human serum is synthesized from blood glucose and urea in vivo.

Enzyme electrochemical preparation of a 3-keto derivative of 1,5-anhydro-D-glucitol using glucose-3-dehydrogenase.

A novel enzymatic organic synthesis was reported, utilizing glucose-3-dehydrogenase (G3DH) and its regeneration via electrochemical methods. We combined the water-soluble G3DH prepared from a marine bacterium, Halomonas sp. alpha-15, and electron mediator with the electrode system in order to regenerate the enzyme. Using this system, the conversion of 1,5-anhydro-D-glucitol (1,5AG), a diabetes marker in human blood, was investigated. The final yield of the product, 3-keto anhydroglucitol (3-ketoAG), which was identified by 13C nuclear magnetic resonance, was 82% based on the initial amount of 1,5AG. The electrochemical yield of the reaction proceeded almost stoichiometrically. The electrochemical conversion rate of 1,5AG was 1.24 mmol/(L.h), and the electrochemical yield of 1,5AG consumption was 80%, whereas that for 3-ketoAG was 60%.