Conformational characteristics of homo-oligopeptides of O-benzyl-L-tyrosine+

Conformational studies of X [-L-Tyr(Bzl)-]n-series bound to polyethyleneglycol (X = H2 Nps; n = 3–8) in the solid state and in solvents of different polarities and capabilities of forming hydrogen bonds are reported. By using i.r. absorption, the occurrence of the β-structure in the higher oligomers in the solid state was established. By means of i.r. absorption and CD the onset of that ordered conformation in solution was assessed as a function of chain length. The effects induced by the presence of the N-protecting group and added base, and by changing the nature of solvent on the conformational preferences of the [-L-Tyr(Bzl)-]n homo-peptides were also examined. The 2-nitrophenylsulphenyl chromophoric derivative of the α-amino group is proposed as a circular dichroism sensor for β-structure in peptides.