title: Tritiated peptides. 12. Synthesis and biological activity of [4-3H-Phe8]substance P.
abstract: Substance P has been prepared 3H labeled at Phe8 by catalytic deiodination of a protected precursor. Synthesis of the precursor was by solid-phase methodology on polydimethylacrylamide resin and by condensation in solution of fragments covering sequences 1-4, 5-7, and 8-11. Free peptide made by each route analyzed satisfactorily and had the same chromatographic characteristics as unlabeled substance P. It was indistinguishable from the latter by radioimmunoassay when N and C terminally directed antisera were used and in the ability to cause contractions of isolated guinea pig ileum. Specific radioactivity was 23 Ci/mmol.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D055598:Chemical Phenomena; D002621:Chemistry; D002851:Chromatography, High Pressure Liquid; D003429:Cross Reactions; D006168:Guinea Pigs; D007082:Ileum / Q000378:metabolism; D066298:In Vitro Techniques; D007553:Isotope Labeling; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D013373:Substance P / Q000276:immunology / Q000494:pharmacology; D014316:Tritium
chemical_list: D000596:Amino Acids; D014316:Tritium; D013373:Substance P