title: Enzymatic metabolism of 3-deoxyglucosone, a Maillard intermediate.
abstract: In order to verify the formation of endogenous 3-deoxyglucosone (3-DG), an intermediate compound in the Maillard reaction, we tried to detect 3-deoxyfructose (3-DF) which is main metabolite of 3-DG. Endogenous 3-DF was detected in the urine of normal and diabetic rats by the oral administration of 3-DG-free feed. Metabolizing activities of crude extracts prepared from porcine organs were examined using methylglyoxal (MG) and 3-DG as substrates. NAD- or NADP-dependent 2-oxoaldehyde dehydrogenase activity was detected in liver, kidney, small intestine and lung. On the other hand, NADH- or NADPH-dependent 2-oxoaldehyde reductase activity was detected in all porcine organs in which liver and kidney contained higher activity of NADPH-dependent enzyme than the other organs. The reductase which catalyzes the reduction of 3-DG to 3-DF and MG to acetol, was purified and characterized from porcine kidney. The enzyme was the same to NADPH-dependent-2-oxoaldehyde reductase from porcine liver, which is speculated to prevent the advanced stage of the Maillard reaction as a self-defense enzyme.
authors.affiliation: Department of Agricultural Chemistry, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, 113, Tokyo, Japan.
authors.forename: F
authors.initials: F
authors.lastname: Hayase
authors.forename: Z Q
authors.initials: ZQ
authors.lastname: Liang
authors.forename: Y
authors.initials: Y
authors.lastname: Suzuki
authors.forename: N
authors.initials: N
authors.lastname: van Chuyen
authors.forename: T
authors.initials: T
authors.lastname: Shinoda
authors.forename: H
authors.initials: H
authors.lastname: Kato