Proceedings book download - 5Z.com

Fig. 2. Plots of chemical shifts of the visible NH protons in the 1 H NMR spectra ofhexapeptides 2-4 as a function of increasing percentages of DMSO (v/v) added to theCDCl 3 solution. Peptide concentration: 1mM.Results and DiscussionHere, we describe our recent FT-IR absorption (Figure 1) and 1 H NMR data (Figure 2) onthe conformational analyses of the linear hexapeptides 2-4. The huge IR absorption bandnear 3330 cm -1 and the sensitivity to the addition of the perturbing agent DMSO of thechemical shifts of only the NH(1) and NH(2) protons clearly support the view that stable3 10 -helical structures are formed by all three hexapeptides examined. These results are ingood accord with those already reported [4] for the related hexapeptide 1.Moreover, in a prelimimary investigation (still underway) of the Paternò-Yangphotocyclization on the hexapeptide substrates 2-4 we already demonstrated the significanteffects induced by the distance and relative orientation of the Bpa/Met side chains on theisomeric product ratios and on the regio- and stereospecificities of the reaction.References1. Kauer, J.C., Erickson-Viitanen, S., Wolfe, H.R., Jr., DeGrado, W.F. J. Biol. Chem. 261, 10695-10700 (1986).2. Deseke, E., Nakatani, Y., Ourisson, G. Eur. J. Org. Chem. 243-251 (1998).3. Toniolo, C., Benedetti, E. Trends Biochem. Sci. 16, 350-353 (1991).4. Moretto, A., Crisma, M., Formaggio, F., Huck, L.A., Mangion, D., Leigh, W.J., Toniolo, C. Chem.Eur. J. 15, 67-70 (2009).587