Flavin oxidation in flavin-dependent N-monooxygenases.

ABSTRACT: Siderophore A (SidA) from Aspergillus fumigatus is a flavin-containing monooxygenase that hydroxylates ornithine (Orn) at the amino group of the side chain. Lysine (Lys) also binds to the active site of SidA; however, hydroxylation is not efficient and H₂ O₂ is the main product. The effect of pH on steady-state kinetic parameters was measured and the results were consistent with Orn binding with the side chain amino group in the neutral form. From the pH dependence on flavin oxidation in the absence of Orn, a pK_a value >9 was determined and assigned to the FAD-N5 atom. In the presence of Orn, the pH dependence displayed a pK_a value of 6.7 ±0.1 and of 7.70 ±0.10 in the presence of Lys. Q102 interacts with NADPH and, upon mutation to alanine, leads

SUBMITTER: Robinson RM 

PROVIDER: S-EPMC6295899 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature