Single Peptide Bonds Exhibit Poly(Pro)II ("Random Coil") Circular Dichroism Spectra
Single Peptide Bonds Exhibit Poly(Pro)II ("Random Coil") Circular Dichroism Spectra
Received April 22, 2005
Web Release Date: June 16, 2005
Isa Gokce, Robert W. Woody, Gregor Anderluh, and Jeremy H. Lakey*
J. Am. Chem. Soc.
ACS Publications
Copyright © 2005 American Chemical Society
Institute of Cell and Molecular Biosciences, University of Newcastle-upon-Tyne, Framlington Place Newcastle-upon-Tyne NE2 4HH, U.K., and Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins Colorado 80525
J.H.lakey@ncl.ac.uk
Abstract:
The far-UV circular dichroism spectra of a series of amino acid derivatives containing single peptide bonds have been measured. The N-acetyl-alanine displays a polyproline (PP) II-like spectrum, but alaninamide shows a very weak positive signal. Similarly Gly-Ala shows a PPII spectrum, but Ala-Gly does not. On heating, the spectrum shows a two-state transition also shown by long PPII polypeptides. Thus the characteristic PPII negative maximum at <200 nm results from the coupling of a peptide bond N-terminal to the chiral -carbon, and therefore the simplest peptide bonds have a preferred conformation that defines the spectrum of disordered proteins of any size.
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