organisms and may more generally be involved in iron metabolism. We have now isolated the gene for the E. coli flavin reductase from a lambda gt11 library. After DNA sequencing we found an open reading frame coding for a polypeptide of 233 amino acids, with a molecular weight of 26,212 and with an N-terminal segment identical to that determined by direct Edman degradation. The coding sequence is preceded
Ye, Hongping; Rong, Ding; Tong, Weida, Journal of the Chemical Society. Perkin transactions II, 1992, # 11, p. 2071 - 2076
作者:Ye, Hongping、Rong, Ding、Tong, Weida、D'Souza, Valerian T.
DOI:——
日期:——
Oxygen Reactivity in Flavoenzymes: Context Matters
作者:Claudia A. McDonald、Rebecca L. Fagan、François Collard、Vincent M. Monnier、Bruce A. Palfey
DOI:10.1021/ja2081873
日期:2011.10.26
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 NS of the reduced flavin. Fructosamine oxidase has a lysine near NS of its flavin. We measured a rate constant of 1.6 x 10(5) M(-1) s(-1) for its reaction with oxygen. The Lys276Met mutant reacted with a rate constant of 291 M(-1) s(-1), suggesting an important role for this lysine in oxygen activation. The dihydroorotate dehydrogenases from E. coli and L. lactis also have a lysine near NS of the flavin. They react with O(2) with rate constants of 6.2 x 10(4) and 3.0 x 10(3) M(-1) s(-1), 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 NS does not exert an effect without an appropriate context; evolution did not find only one mechanism for activating the reaction of flavins with O(2).
Reduction of Hg(II)·EDTA by conformationally biased flavins
作者:Justin J. Hasford、Carmelo J. Rizzo
DOI:10.1016/s0040-4039(98)00001-x
日期:1998.3
The rates of Hg(II) EDTA reduction by conformationally biased flavins are reported. The rates of the reduction correlate to the redox potential of the flavin model. In the case of 8,9,10-trimethylflavin (6), the rate was slower than expected from the redox potential. (C) 1998 Elsevier Science Ltd. All rights reserved.