title: Rapid purification of radioiodinated peptides with Sep-Pak reversed phase cartridges and HPLC.
abstract: A simple, rapid method is described for the purification of radioiodinated peptides for use in radioimmuno- and in radioreceptor assays. Iodinated reaction mixtures are applied directly onto Sep-Pak disposable, reversed phase cartridges equilibrated with phosphate buffer. Unreacted 125-iodide and other non-peptide reaction components are eluted with buffer. The peptide fraction is then eluted with 70% buffer: 30% acetonitrile. The peptide fraction is further purified by reversed phase high pressure liquid chromatography to separate the native peptide and the mono- and diiodo-derivatives. In this study the method is used to prepare 125-iodide-labeled monoiodo-leucine enkephalin and monoiodo-angiotensin II, which are free of the parent peptides and diiodo-derivatives and are of maximum obtainable specific radioactivity. The usefulness of these labeled peptides in radioimmuno- and radioreceptor assays is demonstrated by their binding to specific antibodies and receptors, respectively.
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods; D007457:Iodine Radioisotopes; D009842:Oligopeptides / Q000302:isolation & purification*; D010455:Peptides / Q000302:isolation & purification*; D011863:Radioimmunoassay; D011865:Radioisotope Dilution Technique; D011869:Radioligand Assay; D013056:Spectrophotometry, Ultraviolet
chemical_list: D007457:Iodine Radioisotopes; D009842:Oligopeptides; D010455:Peptides