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Title: 3-nitropropionic acid metabolism and nitrification in legumes
Author: Simpson, D. J.
Awarding Body: University of Wales Swansea
Current Institution: Swansea University
Date of Award: 2000
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The occurrence of 3-nitropropionic acid (3NPA) was measured in 80 legume species. 3 NPA was detected in 19 species, 6 of which have not been recorded previously as containing 3NPA. 3NPA oxidase was detected in 15 of these species, but not in Astragalus hamosus, Astragalus excapus and Astragalus massiliensis. The enzyme was not detected in species which do not accumulate 3NPA. Annual variation in 3NPA levels was detected in field populations of Hippocrepis comosa, with levels significantly higher from April to September. 3NPA was also detected in Hippocrepis comosa leaves in field populations from 16 vice-counties in Britain. The following experiments produced evidence of nitrification in legumes that accumulate 3NPA, 3NPA, nitrite and nitrate were found in the leaves of Hippocrepis comosa, Coronilla viminalis and Securigera securidaca grown in water culture with reduced nitrogen. Significantly more oxidised nitrogen was found in Hippocrepis comosa and Securigera securidaca grown in sterile agar with ammonium than is present in the seed. Nodulated Hippocrepis comosa plants grown in perlite without added nitrogen contained nitrite, nitrate and 3NPA. Higher levels of 3NPA, nitrite and nitrate were measured in soil collected from under Hippocrepis comosa plants than in soil sampled from under a control species, suggesting that the deposition of Hippocrepis comosa litter may have a significant effect on the nitrogen content of the soil. Further characterisation of 3NPA oxidase was carried out. The flavin component was identified as FMN, with 1 molecule FMN per subunit. The stoichiometry of the reaction is complex and non-integral in the consumption of oxygen, with a role suggested for hydrogen peroxide and superoxide.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available