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PubMed1981

Oxidation of ammonia by Nitrosomonas europaea. Definite 18O-tracer evidence that hydroxylamine formation involves a monooxygenase.

NH2OH, the first intermediate in the oxidation of NH4+ to nitrite by the nitrifying bacterium, Nitrosomonas europaea, was recovered as the oxime of cyclohexanone. 15N, 18O-tracer experiments using highly enriched 15NH4Cl and 18O2 yielded oxime that was correspondingly highly enriched (greater than or equal to 92 atom %) in these isotopes. These results show that the source of NH2OH is largely or entirely NH4+, as opposed to hydrazine, which was added to inhibit the further oxidation of NH2OH to nitrite, and that NH4+ yields NH2OH by way of a monooxygenase reaction involving direct insertion of O from O2. The oxidation of NH4+ and NH2OH must be functionally linked in N. europaea, inasmuch as the reducing equivalents required by the monooxygenase to reduce the second atom of O2 to water can arise only through the concomitant oxidation of NH2OH.

Ammonia↗
PubMedDate not supplied

[Abiogenic synthesis of amino acids during polycondensation of formaldehyde and hydroxylamine].

Using two-dimensional thin layer chromatography of dansyl derivatives, studies have been made on the formation of amino acids from formaldehyde and hydroxyamine at the expense of energy from catalytic breakdown of hydroxy peroxide in aqueous medium in the presence of Fe3qt temperature 30 degrees C, pH 2.4. Accumulation of glycine, serine, proline and treonine was observed.

Amino Acids↗
PubMed1999

Reductive Activation of a Hydroxylamine Hemiacetal Derivative of Dehydromonocrotaline: The First Reductively Activated Pyrrolizidine Alkaloid Capable of Cross-Linking DNA.

The acute hepatotoxicity displayed by the pyrrolizidine alkaloids, which obviates their clinical utility, is a result of activation in vivo by cytochrome P450 mediated oxidation. Now the first reductively activated progenitor of the highly cytotoxic dehydropyrrolizidine alkaloid dehydromonocrotaline has been synthesized and demonstrated to mediate interstrand DNA cross-link formation (see scheme); pyrrolizidine alkaloids exert their cytotoxicity through the formation of DNA-DNA interstrand and DNA-protein cross-links.

Journal Article↗
PubMed1997

Salt-Sensitive and Auxotrophic Mutants of Halomonas elongata and H. meridiana by Use of Hydroxylamine Mutagenesis

The killing action and induced mutagenicity inhydroxylamine (HA)-treated cells of two moderately halophilic species of thegenus Halomonas, H. elongata and H. meridiana, wereinvestigated. A high sensitivity of H. elongata and especially ofH. meridiana to HA was found. The efficiency of the mutagenicityobtained with the HA treatment was tested at different salinities. Optimalexperimental conditions for HA mutagenesis of these two moderate halophileswere determined. A clear, efficient mutagenicity of both H. elongataand H. meridiana after HA mutagenesis was achieved. The optimalprocedures yielded a number of useful auxotrophic mutants of H.elongata as well as different salt-sensitive mutants of H.elongata and H. meridiana for further studies. Some of theselatter mutants appeared to be affected in the synthesis of compatiblesolutes.

Journal Article↗