[NMR paper] 2D (1)H/(1)H RFDR and NOESY NMR Experiments on a Membrane-Bound Antimicrobial Peptide Under Magic Angle Spinning.

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2D (1)H/(1)H RFDR and NOESY NMR Experiments on a Membrane-Bound Antimicrobial Peptide Under Magic Angle Spinning.

Related Articles 2D (1)H/(1)H RFDR and NOESY NMR Experiments on a Membrane-Bound Antimicrobial Peptide Under Magic Angle Spinning.

J Phys Chem B. 2013 May 14;

Authors: Ramamoorthy A, Xu J

Abstract
There is significant interest in solving high-resolution dynamic structures of membrane-associated peptides using solid-state NMR spectroscopy. Previous solid-state NMR studies have provided valuable insights into the functional properties of an exciting class of biomacromolecules such as antimicrobial peptides and amyloid peptides. However, it has been a major challenge to apply solid-state NMR techniques to study peptides or proteins that are not labeled with specific isotopes such as 13C, 15N and/or 2H. This study utilizes 2D 1H/1H RFDR (radio-frequency-driven dipolar recoupling) and NOESY pulse sequences under magic angle spinning to study a membrane-bound antimicrobial peptide MSI-78 (or also known as pexiganan). We demonstrate that proton resonances can be assigned and structural constraints - NOE and 1H-1H dipolar couplings - can be measured without the need for any isotopic enrichment. The buildup curves, showing the dependence of the cross peak intensity against the mixing time, obtained from 2D 1H/1H NOESY and RFDR experiments are compared. Our results reveal that the RFDR-recovered 1H-1H dipolar couplings associated with alpha and side chain protons are larger than that with the amide-protons. This study provides a means to measure residual 1H-1H dipolar couplings for the investigation of structure, dynamics, and aggregation of peptides using a suitable model membrane like micelles or bicelles.


PMID: 23672643 [PubMed - as supplied by publisher]



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