GLN(5) SELECTIVELY MONODANSYLATED SUBSTANCE-P AS A SENSITIVE TOOL FORINTERACTION STUDIES WITH MEMBRANES

Substance P (SP) is a neuropeptide endowed with several important biol ogical activities both in the central and peripheral nervous system. T aking advantage of the presence of glutamine residues in SP, the pepti de was labelled with the fluorescent probe monodansylcadaverine using the transglutaminase (TGase)-reaction in order to study interactions b etween SP and model or natural membranes. Although it was verified tha t both adjacent glutamines of the peptide can act as substrate for TGa se in a consecutive reaction, conditions were optimized to selectively label Gln(5). This fluorescent SP analogue was found to adopt environ ment-dependent conformations similar to those of the natural peptide a nd proved to be functionally active on guinea pig trachea. Fluorescenc e spectroscopy was used to demonstrate the potential use of dansylated SP in studies involving interactions with membranes. (C) 1994 Academi c Press, Inc.