title: [mono[125I]iodo-Tyr10,MetO17]-vasoactive intestinal polypeptide. Preparation, characterization, and use for radioimmunoassay and receptor binding.
abstract: Vasoactive intestinal polypeptide (VIP) was labeled with sodium [125I]iodide using the chloramine-T method and subsequently purified by reverse-phase high performance liquid chromatography. Three main 125I-labeled peaks designated A, B, and C resulted from the radioiodination and purification procedures. They were characterized by electrophoresis of tryptic fragments; Edman degradation (for Peaks A and C); enzymatic digestion to amino acids by leucine aminopeptidase, carboxypeptidase Y and Pronase; and treatment with cyanogen bromide. Peak A corresponds to VIP monoiodinated on Tyr10 and with the Met17 residue oxidized to methionine sulfoxide. This [mono[125I]iodo-Tyr10,MetO17]VIP displays the following characteristics. 1) It constitutes quantitatively the major product of the iodination procedure (62.5%); 2) it is well resolved from other labeled and unlabeled products; 3) it is stable (2 months at -20 degrees C); 4) it possesses a high specific activity (2050 Ci/mmol); 5) it maintains the biological activity of native VIP; and 6) it binds to antibody and membrane recognition sites in a specific, saturable, and reversible manner. Reduction of [mono[125I]iodo-Tyr10, Met-O17]VIP to [mono[125I]iodo-Tyr10]VIP does not improve the performance of the tracer in a radioimmunoassay. The method described in this article is simple and rapid and yields a molecular form of 125I-labeled VIP that has been fully characterized and is suitable for use in biological studies.
mesh_terms: D000818:Animals; D002268:Carboxypeptidases / Q000378:metabolism; D002700:Chloramines; D002851:Chromatography, High Pressure Liquid; D003429:Cross Reactions; D003488:Cyanogen Bromide / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D006003:Glycogen / Q000378:metabolism; D006868:Hydrolysis; D007457:Iodine Radioisotopes / Q000378:metabolism; D007700:Kinetics; D007931:Leucyl Aminopeptidase / Q000378:metabolism; D008715:Methionine / Q000031:analogs & derivatives / Q000494:pharmacology; D051379:Mice; D007470:Monoiodotyrosine / Q000378:metabolism; D010446:Peptide Fragments / Q000032:analysis; D011402:Pronase / Q000378:metabolism; D011863:Radioimmunoassay; D011956:Receptors, Cell Surface / Q000378:metabolism*; D018005:Receptors, Vasoactive Intestinal Peptide; D013570:Synaptic Membranes / Q000378:metabolism; D014105:Tosyl Compounds; D014357:Trypsin / Q000378:metabolism; D014660:Vasoactive Intestinal Peptide / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: D002700:Chloramines; D007457:Iodine Radioisotopes; D010446:Peptide Fragments; D011956:Receptors, Cell Surface; D018005:Receptors, Vasoactive Intestinal Peptide; D014105:Tosyl Compounds; C016300:chloramine-T; D014660:Vasoactive Intestinal Peptide; D006003:Glycogen; C048556:vasoactive intestinal peptide, iodo-Tyr(10)-Met sulfoxide(17)-; D008715:Methionine; D002268:Carboxypeptidases; D007931:Leucyl Aminopeptidase; C022633:serine carboxypeptidase; D014357:Trypsin; D011402:Pronase; D007470:Monoiodotyrosine; D003488:Cyanogen Bromide; C013111:methionine sulfoxide