Peptide toxin structure and function by NMR

Peptide toxins are potent and often exquisitely selective probes of the structure and function of ion channels and receptors and as such are of significant interest to the pharmaceutical and biotech industries as both therapeutic leads and pharmacological tools. NMR spectroscopy has played a key role in elucidating the structures of peptide toxins and probing their structure-function relationships. This Chapter describes the application of solution-state NMR to studies of peptide structure and dynamics. The requirements for sample preparation and the types of experiments commonly used to obtain NMR-based restraints for structure determination are discussed, as are cautions regarding the definition of disulfide connectivities and the interpretation of NMR data on peptides lacking ordered structure or containing significant regions of disorder. All of these studies are enhanced by the use of peptides labelled with stable isotopes, which can also be used in NMR relaxation studies to obtain valuable information on peptide dynamics over a range of timescales. Examples of several peptide toxin structures determined on the basis of NMR data are presented in order to illustrate the typical features of such structures and the functional correlates that can be inferred.