Most inducible mutagenesis in Escherichia coli is dependent upon the activity of the UmuDC proteins. The role of UmuC in this process is poorly understood, possibly because of the limited number of genetically characterized umuC mutants. To better understand the function of the UmuC protein in mutagenic DNA repair, we have isolated several novel plasmid-encoded umuC mutants. A multicopy plasmid...

The tetraheme cytochrome c(554) (cyt c(554)) from Nitrosomonas europaea is believed to function as an electron-transfer protein from hydroxylamine oxidoreductase (HAO). We show here that cyt c(554) also has significant NO reductase activity. The protein contains one high-spin and three low-spin c-type hemes. HAO catalyzed reduction of the cyt c(554), ligand binding, intermolecular electron tran...

In the preceding paper (l), hydroxyurea was shown to be a substrate for urease and to be associated with the development of a marked inhibition of the enzyme during t,he course of the reaction. The lack of significant inhibition during the hydrolysis of urea at equal concentrations suggested that the hydroxylamine formed during hydroxyurea hydrolysis was the responsible agent. The inhibitory ef...

PURPOSE The purpose of this study was to develop an X-Band electron paramagnetic resonance imaging protocol for visualization of oxidative stress in biopsies. METHODS The developed electron paramagnetic resonance imaging protocol was based on spin trapping with the cyclic hydroxylamine spin probe 1-hydroxy-3-methoxycarbonyl-2,2,5,5-tetramethylpyrrolidine and X-Band EPR imaging. Computer softw...

A multiheme protein having hydrazine-oxidizing activity was purified from enriched culture from a reactor in which an anammox bacterium, strain KSU-1, was dominant. The enzyme has oxidizing activity toward hydrazine but not hydroxylamine and is a 130-kDa homodimer composed of a 62-kDa polypeptide containing eight hemes. It was therefore named hydrazine-oxidizing enzyme (HZO). With cytochrome c ...

The lymphocyte toxicity assay (LTA) is a proposed surrogate marker of sulfonamide antibiotic hypersensitivity. In the LTA, peripheral blood mononuclear cells (PBMCs) undergo apoptosis more readily in hypersensitive versus tolerant patients when exposed to drug-hydroxylamine metabolites in vitro. The purpose of this study was to identify key gene transcripts associated with increased cytotoxicit...

The sole energy-yielding reaction of the autotrophic nitrifying bacterium Nitrosomonas europaea involves the conversion of ammonium to nmtrite. As early as 1926, Kluyver and Donker postulated that the six electron oxidation proceeds with the intermediary formation of hydroxylamine and hyponitrous acid. Only recently have there been any studies of the biochemical mechanism of chemoautotrophic am...

Among biochemical tests useful in the study of mycobacteria, the hydroxylamine test is shown to be an effective tool in the differentiation of Mycobacterium kansasii from saprophytic strains of group III acid-fast bacilli when combined with the photochromogen test.

This article describes the aza-Piancatelli rearrangement with hydroxylamines to 4-aminocyclopentenones and subsequent transformations that highlight the versatility of the cyclopentene scaffold and the value of the hydroxylamine nucleophile in this transformation.