SOLUTION STRUCTURE OF DEHYDROPEPTIDES - A CD INVESTIGATION

A CD investigation of eleven dehydropeptides is reported The compounds investigated include tri-, tetra-, hexa-, hepta-, and octapeptides an d contain one, two, or three dehydro-phenylalanine (Delta Phe) residue s. The peptides showed different CD profiles depending on chain length , position, and number of dehydro residues. The CD data very much comp lemented that provided by nmr studies, confirming the conformational p reference for beta-bend structures in small peptides (tripeptides), an d 3(10)-helical or alpha-helical structures in longer peptides. The se condary structures were stable in chloroform;solution and were denatur ated by addition of trifluoroacetic acid. Solvent titration experiment s performed by measuring CD as a function of solvent composition provi ded evidence that the order reversible arrow disorder conformational c hanges occurred as cooperative transitions. (C) 1996 John Wiley & Sons , Inc.