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. 1982 Jul;70(1):55–60. doi: 10.1104/pp.70.1.55

De Novo Purine Synthesis in Nitrogen-Fixing Nodules of Cowpea (Vigna unguiculata [L.] Walp.) and Soybean (Glycine max [L.] Merr.) 1

Craig A Atkins 1,2, Anne Ritchie 1,2, Peter B Rowe 1,2, Eric McCairns 1,2, Dorit Sauer 1,2
PMCID: PMC1067085  PMID: 16662479

Abstract

Partially purified, cell-free extracts from nodules of cowpea (Vigna unguiculata L. Walp. cv. Caloona) and soybean (Glycine max L. Merr. cv. Bragg) showed high rates of de novo purine nucleotide and purine base synthesis. Activity increased with rates of nitrogen fixation and ureide export during development of cowpea plants; maximum rates (equivalent to 1.2 micromoles N2 per hour per gram fresh nodule) being similar to those of maximum nitrogen fixation (1-2 micromoles N2 per hour per gram fresh nodule). Extracts from actively fixing nodules of a symbiosis not producing ureides, Lupinus albus L. cv. Ultra, showed rates of de novo purine synthesis 0.1% to 0.5% those of cowpea and soybean. Most (70-90%) of the activity was associated with the particulate components of the nodule, but up to 50% was released from this fraction by osmotic shock. The accumulated end products with particulate fractions were inosine monophosphate and aminoimidazole carboxamide ribonucleotide. Further metabolism to purine bases and ureides was restricted to the soluble fraction of the nodule extract. High rates of inosine monophosphate synthesis were supported by glutamine as amide donor, lower rates (10-20%) by ammonia, and negligible rates with asparagine as substrate.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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