Peptide–Membrane Interactions by Spin-Labeling EPR

Abstract

Site-directed spin labeling (SDSL) in combination with Electron Paramagnetic Resonance (EPR) spectroscopy is a well-established method that has recently grown in popularity as an experimental technique, with multiple applications in protein and peptide science. The growth is driven by development of labeling strategies, as well as by considerable technical advances in the field, that are paralleled by an increased availability of EPR instrumentation. While the method requires an introduction of a paramagnetic probe at a well-defined position in a peptide sequence, it has been shown to be minimally destructive to the peptide structure and energetics of the peptide-membrane interactions. In this chapter, we describe basic approaches for using SDSL EPR spectroscopy to study interactions between small peptides and biological membranes or membrane mimetic systems. We focus on experimental approaches to quantify peptide-membrane binding, topology of bound peptides, and characterize peptide aggregation. Sample preparation protocols including spin-labeling methods and preparation of membrane mimetic systems are also described.

From liposomes to cells: Filling the gap between physicochemical and microbiological studies of the activity and selectivity of host‐defense peptides

“…By entrapping fluorescent dyes inside the liposomes, it is possible to follow peptide‐induced pore formation by measuring their release, and by using molecules of different sizes the pore dimensions can be determined . In addition, it is possible to study peptide‐induced changes in membrane order and fluidity, lipid domains, lipid translocation across the two leaflets (flip‐flop), vesicle aggregation and fusion, and so forth …”

“…Several other aspects of peptide/membrane system can be elucidated by exploiting multiple spectroscopic techniques: IR absorption, fluorescence, circular dichroism, EPR, NMR . For instance, it is possible to determine peptide conformation, aggregation state, depth of insertion, orientation in the membrane and distribution between the two leaflets of the bilayer.…”

Nitroxide spin labels and EPR spectroscopy: A powerful association for protein dynamics studies

“…Due to the sensitivity for the dynamic events in the ps-ns time range [4,11,13,38] , SDSL-EPR spectroscopy can be used to monitor disorder-to-order transitions, induced structural variations and possible conformational modifications arising from the binding processes with partner molecules [39][40][41] . In this section, we will focus on some recent SDSL-EPR studies involving nitroxide labels for the characterization of structural changes, protein-nucleotides and protein-protein interactions mainly through cw-EPR spectroscopy.…”

The two sides of a lipid-protein story

“…δ corresponds to the central linewidth, whose inverse value is proportional to the mobility. Adapted from Dyszy et al (2013) with permission a broad range of local and collective molecular motions of proteins and membranes and have greatly contributed to the success of ESR in protein-membrane studies (Borbat et al 2001;Jeschke et al 2004;McHaourab et al 2011;Sahu and Lorigan 2015;Smirnova and Smirnov 2015).…”