Diacetyl/l-Xylulose Reductase Mediates Chemical Redox Cycling in Lung Epithelial Cells
Environmental Health Science
Reactive carbonyls such as diacetyl (2,3-butanedione) and 2,3-pentanedione in tobacco and many food and consumer products are known to cause severe respiratory diseases. Many of these chemicals are detoxified by carbonyl reductases in the lung, in particular, dicarbonyl/l-xylulose reductase (DCXR), a multifunctional enzyme important in glucose metabolism. DCXR is a member of the short-chain dehydrogenase/reductase (SDR) superfamily. Using recombinant human enzyme, we discovered that DCXR mediates redox cycling of a variety of quinones generating superoxide anion, hydrogen peroxide, and, in the presence of transition metals, hydroxyl radicals. Redox cycling activity preferentially utilized NADH as a cosubstrate and was greatest for 9,10-phenanthrenequinone and 1,2-naphthoquinone, followed by 1,4-naphthoquinone and 2-methyl-1,4-naphthoquinone (menadione). Using 9,10-phenanthrenequinone as the substrate, quinone redox cycling was found to inhibit DCXR reduction of l-xylulose and diacetyl. Competitive inhibition of enzyme activity by the quinone was observed with respect to diacetyl (K
Yang, S., Jan, Y., Mishin, V., Heck, D. E., Laskin, D., & Laskin, J. (2017). Diacetyl/l-Xylulose Reductase Mediates Chemical Redox Cycling in Lung Epithelial Cells. Chemical Research in Toxicology, 30 (7), 1406-1418. https://doi.org/10.1021/acs.chemrestox.7b00052
Originally published in Chemical Research in Toxicology, 30 (7), 1406-1418. The original material can be found here.