(Cholestanyloxycarbonyl)benzyl Esters as Peptide Substituents: Conformational Properties of Fully Protected Oligo-L-Lysines with C-Terminal (Cholestanyloxycarbonyl)benzyl and Benzyl Ester Moieties

Article abstract of DOI:10.1002/hlca.19860690214

This study involves L-lysine oligo peptides, protected at the N-terminus by the Nps and at the ε-amino functions by Boc groups.Two series were prepared from dimer to octamer, one containing the p-<(cholestan-3β-yloxy)carbonyl>benzyl, the other one the benzyl ester group at the C-terminus.Conformational analyses were performed by IR absorption.The occurence of the intermolecular β-structure in the solid state and in CH2Cl2 solution was demonstrated for the highest oligomers.The relative stabilities of the self-associated species were determined by adding a variety of polar solvents to the CH2Cl2 solutions.The cholestanyl-containing peptides have a lower propensity to self-aggregate than the benzyl-ester analogues.Self-aggregation and decreasing solubility run in parallel.It was also directly shown that soluble urea derivatives may disrupt intermolecular H-bonds in CH2Cl2, a point of practical interest, particularly in solid-phase peptide synthesis.