The 2-nitrophenylsulphenyl chromophoric derivative of the α-amino-group as a circular dichroism probe for the β-structure in oligo-tyrosine peptides

Abstract

A comparison of circular dichroism (c.d) spectra has revealed that the randomly coiled lower oligomers of the Nps[L-Tyr(Bzl)]nGly-OPEG-M [n= 3–8, Nps = 2-nitrophenylsulphenyl, Bzl = PhCH2, OPEG-M = poly(ethylene glycol monomethyl ether)] peptide series have a positive Cotton effect at 350–400 nm, associated with the 2-nitrophenylsulphenylamino-chromophore, while the β-forming higher oligomers have a negative Cotton effect in that region of their spectra, this suggests the use of the Nps group at the N-terminus as a c.d. probe for β-structure in oligo-Tyr-peptides.