title: Binding affinities to rat brain synaptosomes--synthesis of biotinylated analogues of Substance P.
abstract: The synthesis of four biotinylated analogues of Substance P is described. The affinities of these analogues and of their complexes with avidin for the 125I-Bolton Hunter Substance P binding sites on rat brain synaptosomes were determined. While these biotinylated peptides complexed to avidin retain a good biological activity on the guinea-pig ileum bioassay, we observe a net decrease in their binding affinities in the central nervous system. The present study confirms that in the central nervous system the higher affinity is related to the N-terminal tetrapeptide and establishes that the free amino group (N-alpha-Arg and N-epsilon-Lys) are not essential in the binding.
mesh_terms: D000345:Affinity Labels / Q000138:chemical synthesis; D000818:Animals; D001681:Biological Assay; D001710:Biotin; D001921:Brain / Q000378:metabolism*; D007082:Ileum / Q000378:metabolism; D008297:Male; D051381:Rats; D018040:Receptors, Neurokinin-1; D017981:Receptors, Neurotransmitter / Q000378:metabolism*; D013329:Structure-Activity Relationship; D013373:Substance P / Q000031:analogs & derivatives* / Q000378:metabolism; D013574:Synaptosomes / Q000378:metabolism
chemical_list: D000345:Affinity Labels; D018040:Receptors, Neurokinin-1; D017981:Receptors, Neurotransmitter; D013373:Substance P; D001710:Biotin