title: [3H] Boc [Nle28, 31]CCK27-33, a new highly labelled ligand for CCK receptors: binding on brain and on pancreas.
abstract: Preliminary results on the binding of [3H]Boc[Nle28, 31]CCK27-33, designated [3H]Boc[diNle]CCK7, on mouse brain and rat pancreas membranes are presented. This new ligand for CCK receptors possesses a high specific activity (144 Ci/mmole), and binds in a saturable manner to mouse brain (Kd = 0.49 nM, Bmax = 49 fmoles/mg protein) and rat pancreas (Kd = 4.4 nM, Bmax = 696 fmoles/mg protein). Unlabelled Boc[diNle]CCK7 displaces [125I]CCK8 from its binding sites on mouse brain membranes with a high affinity, slightly superior to that of CCK8. The order of potencies to displace [3H]Boc[diNle]CCK7 from its binding sites was the same in mouse brain and rat pancreas: [3H]Boc[diNle]CCK7 greater than CCK8, Boc-CCK7 greater than non-sulfated CCK8, the pancreas binding sites being more discriminative than the brain binding sites. Thus, [3H]Boc[diNle]CCK7 is a very promising new probe for the characterization of CCK receptors and their interaction with different CCK fragments.
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism*; D002766:Cholecystokinin / Q000378:metabolism*; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D051379:Mice; D010179:Pancreas / Q000378:metabolism*; D010446:Peptide Fragments; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011949:Receptors, Cholecystokinin; D012844:Sincalide / Q000378:metabolism / Q000031:analogs & derivatives; D013329:Structure-Activity Relationship
chemical_list: D010446:Peptide Fragments; D011956:Receptors, Cell Surface; D011949:Receptors, Cholecystokinin; D002766:Cholecystokinin; C047716:cholecystokinin (27-33), tert-butyloxycarbonyl-Nle(28,31)-; D008274:Magnesium; D012844:Sincalide