Raman spectroscopy shows antifreeze glycoproteins interact with highly oriented pyrolytic graphite



Raman spectra of a mixture of antifreeze glycoproteins (AFGP) 6, 7 and 8 adsorbed on a highly oriented pyrolytic graphite (HOPG) surface spanning the range of 50 to 4500 cm−1 were measured. It was found that the Raman signature of AFGP had been significantly altered because of its interaction with the HOPG surface; when compared with the spectra of bulk AFGP compounds, at least three new peaks were observed around 860, 940 and 1000 cm−1, and two other peaks that were not well resolved in the bulk spectra around 1050 and 1155 cm−1 were enhanced and well discriminated. The peak positions depended on the facet of HOPG presented to the proteins, and their relative intensities depended on the concentration of AFGP used in the adsorption experiment. The results indicated the possibility of multiple binding sites of AFGP on HOPG surfaces. Copyright © 2005 John Wiley & Sons, Ltd.