NMR study of the metabolic N-15 isotopic enrichment of cyanophycin synthesized by the cyanobacterium Synechocystis sp. strain PCC 6308

H-1, C-13 and N-15 nuclear magnetic resonance (NMR) spectroscopy has been u sed to characterize cyanophycin, a multi-L-arginyl-poly-[L-aspartic acid] p olypeptide from the cyanobacterium Synechocystis sp. strain PCC 6308. H-1,C -13 and N-15 chemical shifts and (1)J(HN) and (1)J(CN) coupling constants w ere measured in isolated N-15-labeled cyanophycin, and showed chemical shif t values and J-couplings consistent with the reported polypeptide structure . N-15 enrichment levels were determined from the extent of H-1-N-15 J-coup ling in H-1 NMR spectra of cyanophycin. Similar experiments using C-13-N-15 coupling in C-13 NMR spectra were not useful in determining enrichment lev els. (C) 1999 Elsevier Science B.V. All rights reserved.