NATURAL-ABUNDANCE OF N-15 IN AMINO-ACIDS AND POLYAMINES FROM LEGUMINOUS NODULES - UNIQUE N-15 ENRICHMENT IN HOMOSPERMIDINE

The natural N-15 abundance (delta(15)N value) in acetylpropyl derivati ves of amino acids and in ethyloxycarbonyl derivatives of polyamines w as determined using a gas chromatography/combustion/mass spectrometer (GC/C/MS). delta(15)N values determined for 12 amino acids and five po lyamines by GC/C/MS were identical to those obtained by a direct combu stion method using an automatic nitrogen and carbon analysis (AMCA) ma ss spectrometer, the difference being less than +/-1.0% in most cases, The GC/C/MS method was used to analyse delta(15)N values in the amino acids and polyamines from root nodules of pea and faba bean and from stem nodules of Sesbania rostrata, The analysis of delta(15)N values r evealed that homospermidine had high delta(15)N values, as much as +40 parts per thousand, while the amino acids investigated had delta(15)N values between -3 and +6 parts per thousand, putrescine between +2 an d +8 parts per thousand, cadaverine between fl and +7 parts per thousa nd, spermidine between -2 and +4 parts per thousand, and spermine betw een 0 and +6 parts per thousand, The mechanism of N-15 enrichment in h omospermidine is discussed.