Deuterium magic angle spinning NMR used to study the dynamics of peptides adsorbed onto polystyrene and functionalized polystyrene surfaces.

ABSTRACT: LK?14 is a 14 amino acid peptide with a periodic sequence of leucine and lysine residues consistent with an amphipathic ?-helix. This "hydrophobic periodicity" has been found to result in an ?-helical secondary structure at air-water interfaces and on both polar and nonpolar solid polymer surfaces. In this paper, the dynamics of LK?14 peptides, selectively deuterated at a single leucine and adsorbed onto polystyrene and carboxylated polystyrene beads, are studied using (2)H magic angle spinning (MAS) solid state NMR over a 100 °C temperature range. We first demonstrate the sensitivity enhancement possible with (2)H MAS techniques, which in turn enables us to obtain high-quality (2)H NMR spectra for selectively deuterated peptides adsorbed onto solid polymer surfaces. The extensive literature shows that the dynamics of leucine side chains are sensitive to the local structural environment of the protein. Therefore, the degree to which the dynamics of leucine side chains and the backbone of the peptide LK?14 are influenced by surface proximity and surface chemistry is studied as a function of temperature with (2)H MAS NMR. It is found that the dynamics of the leucine side chains in LK?14 depend strongly upon the orientation of the polymer on the surface, which in turn depends on whether the LK?14 peptide adsorbs onto a polar or nonpolar surface. (2)H MAS line shapes therefore permit probes of surface orientation over a wide temperature range.

SUBMITTER: Breen NF 

PROVIDER: S-EPMC3253709 | biostudies-literature | 2011 Aug

REPOSITORIES: biostudies-literature