Observations on cation-binding characteristics and nuclear magnetic resonance spectra of the N-carboxymethyl and N-acetyl analogs of heparin

Abstract

Based on the observed paramagnetic relaxation effects of Cu2+ and Fe3+ ions and the chemical shift displacements induced by Ca2+ ions, nuclear resonance spectroscopy has been used to compare cation-binding characteristics of heparin with those of its N-carboxymethyl and N-acetyl analogs and related polyanions. Heparin is unique in exhibiting a high affinity for all three cations. Among the other polymers, binding selectivities differ notably. Such factors as the incidence and distribution of anionic charges are discussed. The preparation of the N-carboxymethyl analog of heparin is described, and 1H and 13C nuclear magnetic resonance spectroscopic data are reported for it, as well as for the N-acetyl analog. Keywords: heparin, N-carboxymethyl analog, N-acetyl analog, cation binding, ion-selectivity, anionic charge distribution.