Simulations of transferred NOE in a ternary peptide-receptor-lipid complex

Analyses of neuropeptides interacting with their receptors in presence of lipid membranes require the use of spin systems including several molecules (peptide, membrane, receptor) in at least three states (free, membrane-bound and receptor-bound ligand). Moreover, the exchange rates can be arbitrary. We have developed a program, based on the generalized relaxation matrix method, capable of treating all direct and indirect spin interactions. The program allows a simulation of homonuclear NOE and ROE experiments in case of arbitrary exchange rates, for systems with internal mobility and groups of equivalent spins. We present here some simulations for a system of three states, such as the free, membrane-bound and receptor-bound ligand, aiming at defining more precisely the limits of the transferred NOE experiments for the determination of the receptor-bound conformation of a neuropeptide.