Apart from x-ray crystallography and neutron diffraction dedicated to crystallised proteins, all other biophysical techniques that are well suited for proteins in solution could be adapted to interfacial analysis, although there are limitations depending upon the heterogeneous character of the protein-sorbent phase under study. Recent progresses in NMR spectroscopy allows the determination of structures of small membrane proteins (up to 20 kDa) in detergent micelles (Booth et al. 2004; Tamm et al. 2003). This opens a new window into the study of the dynamics of proteins at the aqueous-fluid interface. A first high-resolution structural characterisation using solid-state NMR was carried out for statherin, a protein of around 5 kDa, adsorbed onto an inorganic support such as hydroxyapatite in the hydrated and lyophilised states (Long et al. 2001), enlightening the role of water in stabilising the helical structure of the adsorbed peptide. A combined study involving CD and NMR spectroscopies has shown the localised a-helix unfolding of small peptides adsorbed at an aqueous-colloidal interface (Read and Burkett 2003).
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