Common conformational characteristics in bioactive peptides which exhibit multifunctional properties

The majority of immune systems mediators are polypeptide or proteins by nature. They serve as messengers in the signal transfer between various immunocompetent cells providing cell cooperation during the development of the immune responses. Peptide and polypeptide molecules are implicated in an intricate network of bioregulatory processes resulting in homeostasis. The biological function ("function" code) of biologically active peptides is determined by the conformations coded in their primary structure ("structure" code). Biologically active fragments originating from food proteins should be taken into account as potential modulators of various regulatory processes in the body. In contrast to endogenous bioactive peptides, many food-derived sequences reveal multifunctional properties -i.e. specific peptide sequences having two different biological activity have been reported. In the following table are reported few sequences used in this work. ProteinFragmentNameBiological ActivityRef. beta-Casein(60-66) YPFPGPIbeta-Casomorphin-7Opioid, Immunomodulatory1,2,5 beta-Casein(191-193) LLYImmunopeptideImmunomodulatory1 beta-Lactoglobulin(102-105) YLLFbeta-LactorphinOpioid Agonist1,3 beta-Haemoglobin(31-35) LVVYPLVV-HemorphinOpioid, Immunomodulatory4 It is well accepted that the binding of the ligand to its receptor is mediated by hydrogen bonding, hydrophobic interactions, and shape complementarity, but the relative contribution of each of these interactions is still poor understood for the bioactive sequences here observed. In our work on synthetic opioid peptides we studied conformational behavior of following conventionally protected sequences: -LVVYP-, -LVVY-, -LVVF-,-LLY-, and -LLF-. These products have been synthesized, purified, and then analyzed by NMR spectroscopy, employing both mono- and bi-dimensional techniques. The results obtained are here compared and discussed. References 1.H.Meisel Biopolymers (1997) 43, 119-128 2.E.Fenude, Roggio A.M., XII° National Congress of Società Chimica Italiana (2006), Firenze 10-15/09/2006 3.E.Fenude, S.Dedola, M.Fais Congress "Complex Systems: structure,properties, reactivity, and dynamics"(2005) Alghero, 13-15/06/2005 4.R.V.Petrov, A.A.Mikhailova, L.A. Fonona, Biopolymers (1997) 43, 139-146. 5. G. Micera, D. Sanna, & al, Journal of Inorganic Biochemistry(1998) 69, 91-95