SOLUTION CONFORMATION OF NOCICEPTIN

Nociceptin, a novel heptadecapeptide, interacts with ORL1 a G protein- coupled receptor whose sequence is closely related to that of the kapp a opioid receptor but has no opioid activity. We have Investigated the conformational preferences of Nociceptin also in comparison to Dynorp hin A, The N-terminal part of Nociceptin has the same conformational p references of She message of endogenous opioids but the C-terminal par t of the sequence is more flexible than the corresponding address of D ynorphin A. [Tyr(1)]-Nociceptin, while retaining nociceptive activity, has also an opioid activity comparable to that of enkephalins. (C) 19 97 Academic Press.