Binding affinities to rat brain synaptosomes – synthesis of biotinylated analogues of Substance P

Publisher Website
Google Scholar
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‐α‐Arg and N‐α‐Lys) are not essential in the binding.