Shoots excised from pea seedlings (Pisum sativum) at different stages of growth (2, 9, 13 and 21 day old) were supplied with [U-19C] adenine. Incorporation of radioactivity into the resulting metabolites was traced and measured. In the 2 day old shoots, adenine was converted to the adenosine nucleotides AMP, ADP and A1P and incorporated into nucleic acids. In 9, 13 and 21 day old shoots radioactivity was mostly incorporated into the purine catabolites xanthine and allantoin, and to a lesser extent into adenosine nucleotides a very small proportion of the radioactivity was incorporated into hypoxanthine and inosine. These experiments were repeated with 13 and 21 day old seedlings in the presence of allopurinol which fed, simultaneously, with [U-19C] adenine to the plants. Marked changes in the pattern of incorporation of the precursor into its metabolites were observed. Incorporation of radioactivity into allantoin and xanthine decreased, whereas incorporation into inosine, hypoxanthine and the adenosine nucleotides increased. It is concluded from the results obtained that allopurinol blocks the reactions leading to formation of xanthine and uric acid. Attempts to detect traces of radioactive uric acid, IMP and guanine derivatives in the presence of absence of allopurinol failed. In the expectation of directly demonstrating xanthine oxidase activity in seedlings of P. sativum and Lens eacutenta, enzymic extracts of these seedlings were made and incubated with [U-14C] adenine, [8-19C] hypoxanthine. However, whereas the adenine was converted to hypoxanthine and AMP, the hypoxanthine was recovered unchanged.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:636974 |
| Date | January 1980 |
| Creators | Firuzzray, M. |
| Publisher | Swansea University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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