NADH oxidase activity of Bacillus subtilis nitroreductase NfrA1: Insight into its biological role

AbstractNfrA1 nitroreductase from the Gram-positive bacterium Bacillus subtilis is a member of the NAD(P)H/FMN oxidoreductase family. Here, we investigated the reactivity, the structure and kinetics of NfrA1, which could provide insight into the unclear biological role of this enzyme. We could show that NfrA1 possesses an NADH oxidase activity that leads to high concentrations of oxygen peroxide and an NAD+ degrading activity leading to free nicotinamide. Finally, we showed that NfrA1 is able to rapidly scavenge H2O2 produced during the oxidative process or added exogenously.Structured summaryMINT-7990140: nfrA1 (uniprotkb:P39605) and nfrA1 (uniprotkb:P39605) bind (MI:0407) by X-ray crystallography (MI:0114

Isolation and Characterization of α,β-Unsaturated γ-Lactono-Hydrazides from <i>Streptomyces</i> sp.

Two novel α,β-unsaturated γ-lactono-hydrazides, geralcin A (<b>2</b>) and geralcin B (<b>3</b>), were isolated from <i>Streptomyces</i> sp. LMA-545. This unusual scaffold consists of the condensation of alkyl-hydrazide with an α,β-unsaturated γ-lactone, 3-(5-oxo-2<i>H</i>-furan-4-yl)­propanoic acid (<b>1</b>), which was isolated from the same broth culture. Amberlite XAD-16 solid-phase extraction was used during the cultivation step, and the trapped compounds (<b>1</b>–<b>3</b>) were eluted from the resin with methanol. The structures were elucidated using ¹H, ¹³C, and ¹⁵N NMR spectroscopic analysis and high-resolution mass spectrometry. Geralcin B (<b>3</b>) was cytotoxic against MDA231 breast cancer cells with an IC₅₀ of 5 μM