Oxygen reactivity in flavoenzymes: Context matters
(2011) Journal of the American chemical society — Vol. 133, n° 42, p. 16809-16811 (2011)
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- Abstract
- Many flavoenzymes-oxidases and monooxygenases-react faster with oxygen than free flavins do. There are many ideas on how enzymes cause this. Recent work has focused on the importance of a positive charge near N5 of the reduced flavin. Fructosamine oxidase has a lysine near N5 of its flavin. We measured a rate constant of 1.6 × 10 <sup>5</sup> M <sup>-1</sup> s <sup>-1</sup> for its reaction with oxygen. The Lys276Met mutant reacted with a rate constant of 291 M <sup>-1</sup> s <sup>-1</sup>, suggesting an important role for this lysine in oxygen activation. The dihydroorotate dehydrogenases from E. coli and L. lactis also have a lysine near N5 of the flavin. They react with O <inf>2</inf> with rate constants of 6.2 × 10 <sup>4</sup> and 3.0 × 10 <sup>3</sup> M <sup>-1</sup> s <sup>-1</sup>, respectively. The Lys66Met and Lys43Met mutant enzymes react with rate constants that are nearly the same as those for the wild-type enzymes, demonstrating that simply placing a positive charge near N5 of the flavin does not guarantee increased oxygen reactivity. Our results show that the lysine near N5 does not exert an effect without an appropriate context; evolution did not find only one mechanism for activating the reaction of flavins with O <inf>2</inf>. © 2011 American Chemical Society.
- Affiliations
University of Michigan Department of Biological Chemistry Case Western Reserve University Department of Pathology
Citations
McDonald, C. A., Fagan, R. L., Collard, F., Monnier, V. M., & Palfey, B. A. (2011). Oxygen reactivity in flavoenzymes: Context matters. Journal of the American chemical society, 133(42), 16809-16811. https://doi.org/10.1021/ja2081873 (Original work published 2011)