Recent Progress in the Solid-State NMR Studies of Short Peptides: Techniques, Structure and Dynamics

In this chapter, progress in the solid-state NMR studies of short peptides published during the last 10 years is reviewed. The chapter is divided into sections. After the preface, Section 2 presents a comprehensive introduction to the modern NMR techniques which are used in structural studies of peptides. Techniques employing fast magic-angle spinning with sample rotation over 40 kHz are highlighted. Two-dimensional homo- and heteronuclear correlation experiments with inverse detection (based on J and dipolar interactions) are discussed for spin I = 1/2 nuclei as well as for quadrupolar nuclei (I > 1/2). Section 3 reviews methodologies which are employed to analysis of molecular dynamics of peptides in the solid state. Tools for inspection of local molecular motions in different time scales such as measurements of relaxation times, chemical shift anisotropies, line-shape analysis of static spectra and heteronuclear dipolar couplings obtained by means of recoupling sequences are shortly discussed. Section 4 is devoted to problem of polymorphism and solvatomorphism. Special attention is paid to NMR study of hydrates and their solid-state transformations. In Section 5, the complementarity of theoretical (GIPAW, GIAO, ONIOM) and NMR methods in structural analysis of peptides in the solid state is reviewed. The attention is paid to the assignment problem, refinement of crystal and molecular structure for disordered peptides and correlations between theoretical and experimental shielding parameters for systems which are under fast exchange regime.