biostudies-literatureSedlacek VCzech Science FoundationGrant Agency of Masaryk University902https://www.ebi.ac.uk/biostudies/studies/S-EPMC9137774biostudies-literatureUnknown11(5)<i>Paracoccus denitrificans</i> ArsH is encoded by two identical genes located in two distinct putative arsenic resistance (<i>ars</i>) operons. <i>Escherichia coli</i>-produced recombinant N-His₆-ArsH was characterized both structurally and kinetically. The X-ray structure of ArsH revealed a flavodoxin-like domain and motifs for the binding of flavin mononucleotide (FMN) and reduced nicotinamide adenine dinucleotide phosphate (NADPH). The protein catalyzed FMN reduction by NADPH via ternary complex mechanism. At a fixed saturating FMN concentration, it acted as an NADPH-dependent organoarsenic reductase displaying ping-pong kinetics. A 1:1 enzymatic reaction of phenylarsonic acid with the reduced form of FMN (FMNH₂) and formation of phenylarsonous acid were observed.Antioxidants (Basel, Switzerland)The ArsH Protein Product of the <i>Paracoccus denitrificans ars</i> Operon Has an Activity of Organoarsenic Reductase and Is Regulated by a Redox-Responsive Repressor.PMC9137774GA 16-18476SMUNI/A/1604/2020Kucera ISedlacek VKryl MfalseThe ArsH Protein Product of the <i>Paracoccus denitrificans ars</i> Operon Has an Activity of Organoarsenic Reductase and Is Regulated by a Redox-Responsive Repressor.<i>Paracoccus denitrificans</i> ArsH is encoded by two identical genes located in two distinct putative arsenic resistance (<i>ars</i>) operons. <i>Escherichia coli</i>-produced recombinant N-His₆-ArsH was characterized both structurally and kinetically. The X-ray structure of ArsH revealed a flavodoxin-like domain and motifs for the binding of flavin mononucleotide (FMN) and reduced nicotinamide adenine dinucleotide phosphate (NADPH). The protein catalyzed FMN reduction by NADPH via ternary complex mechanism. At a fixed saturating FMN concentration, it acted as an NADPH-dependent organoarsenic reductase displaying ping-pong kinetics. A 1:1 enzymatic reaction of phenylarsonic acid with the reduced form of FMN (FMNH₂) and formation of phenylarsonous acid were observed.2022-01-01T00:00:00Z2022 May2026-04-08T10:24:43.84Z2024-11-15T11:14:39.142ZS-EPMC91377743562476610.3390/antiox11050902