Cyclic peptides and their interaction with peptide coated surfaces

Focusing on biochemical and pharmaceutical inhibitor systems the interactio n of cyclic peptides with model peptides have been investigated by 4TR-FTIR -spectroscopy. Information about the participation of special functional gr oups e.g. COOH, COO-, NH3+ or peptide backbone was gathered by observing cy clohexapeptides (c(X1LX2LX3)) which are interacting with covalently coated Si-ATR-crystals (L-arginine, tripeptide I (aNS), tripeptide II (SNa)). To d etermine the interaction, further studies about the band sequence (1800-150 0 cm(-1)) for non-adsorbed cyclohexapeptides and for the interaction with t he silicon surface (SiOH) were necessary. The spectra of the interacting cy clohexapeptides with the SiOH-groups were treated like reference spectra fo r the evaluation of the peptide-peptide interaction. Based on these spectra , we can conclude that there is peptide-peptide interaction with the coatin g and not with the residual OH-groups. Determination of interaction mechanisms was done by spectra which represent adsorbed molecules only. The amount of adsorbed molecules was considerably less than a monolayer. Therefore the intensities of the spectra are about 10(-4) absorbance units. The spectra contain information about both changes of the coating and of the cyclohexapeptide. (C) 2001 Elsevier Science B.V. All rights reserved.