15N-NMR Spectroscopy. V. Investigation of Peptides and Sequence Polyamides Containing ω-Aminosulfonic Acids

Abstract
Natural abundance 15N-NMR spectra of ten different sequence polymers containing taurine, γ-aminopropanesulfonic acid, or sulfanilic acid as well as various aminocarboxylic acids were measured in trifluoroacetic acid. Strong neighboring residue effects and a relationship between chemical shift and chain length of the ω-amino acyl residues are observed and discussed. Isomeric sequences of first and second order like (Tau-γ-Abu)n, and (γ-Aps-β-Ala)n or (Tau-Gly-β-Ala)n, and (Tau-β-Ala-Gly)n, show different spectra. The deprotonation of the sulfonamide groups in alkaline solution results in a downfield shift as well as a substantial decrease in signal intensity.