Glyceraldehyde-3-phosphate dehydrogenase as a quinone reductase in the suppression of 1,2-naphthoquinone protein adduct formation

作者：Miura Takashi; Shinkai Yasuhiro; Hirose Reiko; Iwamoto Noriko; Cho Arthur K; Kumagai Yoshito^*

来源：Free Radical Biology and Medicine, 2011, 51(11): 2082-2089.

DOI：10.1016/j.freeradbiomed.2011.09.008

• GAPDH
• 1,2-Napthoquinone
• Two-electron reduction
• Covalent modification
• Free radicals

1,2-Naphthoquinone (1,2-NQ) is electrophilic, and forms covalent bonds with protein thiols, but its two-electron reduction product 1,2-dihydroxynaphthalene (1,2-NQH(2)) is not, so enzymes catalyzing the reduction with reduced pyridine nucleotides as cofactors could protect cells from electrophile-based chemical insults. To assess this possibility, we examined proteins isolated from the 9000 g supernatant from mouse liver for 1,2-NQ reductase activity using an HPLC assay procedure for the hydroquinone of 1,2-NQ and Cibacron Blue 3GA column chromatography and Western blot analysis with specific antibody to determine 1,2-NQ-bound proteins. Among the proteins with high affinities for pyridine nucleotides that also inhibited 1,2-NQ-protein adduct formation in the presence of NADH, a 37-kDa protein was found and identified as glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Using recombinant human GAPDH, we found that this glycolytic enzyme indeed catalyzes the two-electron reduction of 1,2-NQ accompanied by extensive NADH consumption under 20% oxygen conditions. When either 1,2-NQH2 or 1,2-NQ was incubated with GAPDH in the presence of NADH, minimal covalent bonding to the enzyme occurred compared to that in its absence. These results indicate that GAPDH can inhibit 1,2-NQ-based electrophilic protein modification by conversion to the nonelectrophilic 1,2-NQH2 via an NADH-dependent process.

• 出版日期2011-12-1