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Title: Pyrimidine primary and secondary metabolism in plants
Author: Turan, Y.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1995
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In this study, the biosynthesis of albizziine has been elucidated, and a direct precursor relationship shown to exist between uracil and albizziine. This was confirmed by the demonstration that [2-14C]uracil specifically labels C-5 of albizziine. It is concluded that the biosynthetic sequence involves the hydroxylation of uracil to isobarbituric acid, then amination to 5-aminouracil, followed by hydrogenation and ring-opening, to yield albizziine. 2,3-Diaminopropanoic acid was shown to be formed from albizziine by the action of β-ureidopropionase. Thus, the formation of albizziine and 2,3-diaminopropanoic acid represents a further aspect of the interfacing of pyrimidine primary and secondary metabolism through uracil. Lathyrine was shown to be catabolyzed in Lathyrus tingitanus to yield the non-protein amino acid 4-hydroxyhomoarginine, and it was thus confirmed that 4-hydroxyhomoarginine is a catabolite rather than a precursor of lathyrine. 2-Amino-4-carboxypyrimidine, the immediate precursor of the lathyrine ring-system, was shown to be synthesized enzymically from uracil. The relative amount of exogenously supplied uracil diverted into production of the isomeric pyrimidinyl amino acids willardiine and isowillardiine in Pisum sativum, and also that diverted into the production of the pyrimidine amino acid lathyrine in Lathyrus tingitanus was determined. Uracil was shown to have a pronounced inhibitory effect on the germination and growth of Phaseolus aureus and Glycine max. As these plants do not produce pyrimidine-derived secondary products, this observation is consistent with the view that production of such compounds is a detoxification mechanism for bioactive pyrimidines.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available