SYNTHESIS OF N-15(OMEGA)-HYDROXY-L-ARGININE AND ESR AND N-15-NMR STUDIES FOR THE ELUCIDATION OF THE MOLECULAR MECHANISM OF ENZYMATIC NITRIC-OXIDE FORMATION FROM L-ARGININE(+)++))

N-omega-Hydroxy-L-arginine (2) was prepared by a multi-stage synthesis ; the key step was the addition of hydroxylamine to the protected cyan amide 8. The presence of N-hydroxyguanidines was confirmed, above all, by N-15-NMR investigations. N-15(omega)-Hydroxy-L-arginine (2) was co nverted quantitatively to (NO)-N-15 by NO synthases from macrophages. (NO)-N-15 was identified by ESR-spectroscopy. These experiments confir m that N-15(omega)-hydroxy-L-arginine (2) is an intermediate in the bi osynthesis of NO from arginine (1) and that the N-hydroxylated N-atom is present in the NO formed.