Selection of side-chain carbons in a high-molecular-weight, hydrophobic peptide using solid-state spectral editing methods

Abstract

Solid-state spectral editing techniques have been used by others to simplify ¹³C CPMAS spectra of small organic molecules, synthetic organic polymers, and coals. One approach utilizes experiments such as cross-polarization-with-polarization-inversion and cross-polarization-with-depolarization to generate subspectra. This work shows that this particular methodology is also applicable to natural-abundance ¹³C CPMAS NMR studies of high-molecular-weight biopolymers. The editing experiments are demonstrated first with model peptides and then with α-elastin, a high-molecular-weight peptidyl preparation obtained from the elastic fibers in mammalian tissue. The latter has a predominance of small, nonpolar residues, which is evident in the crowded aliphatic region of typical ¹³C CPMAS spectra. Spectral editing is particularly useful for simplifying the aliphatic region of the NMR spectrum of this elastin preparation.