title: Measurement of opioid peptides with combinations of reversed phase high performance liquid chromatography, radioimmunoassay, radioreceptorassay, and mass spectrometry.
abstract: Novel state-of-the-art mass spectrometric methods have been developed and are now used to identify and to quantify enkephalins and other neuropeptides in biological tissue extracts. As the first step, RP-HPLC gradient elution is performed of a Sep-Pak treated peptide-rich fraction from a tissue extract, and the eluent is monitored by a variety of post-HPLC detectors. In an effort to maximize the structural information that can be obtained from the analysis, UV (200 nm) provides the analog absorption trace; receptorassay analysis (RRA) data of all (90) fractions that are collected are used to construct the profile of opioid-receptoractive peptides; radioimmunoassay (RIA) of selected HPLC fractions at retention times corresponding to the retention time of standards, or in some special cases of all 90-fractions, provides immunoreactivity information; and fast atom bombardment mass spectrometry (FAB-MS) in two modes - corroboration of the (M+H)+ of the expected peptide, or MS/MS to monitor an amino acid sequence-determining fragment ion unique to that peptide in the selected ion monitoring (SIM) mode - provides structural information. As a demonstration of the level of quantification sensitivity that can be attained by these novel MS methods, FAB-MS-MS-SIM of solutions of synthetic leucine enkephalin was sensitive to the 70 femtomole level. This paper discusses RIA versus RRA data, and recent MS measurements of peptides in human tissues.
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004723:Endorphins / Q000032:analysis*; D005260:Female; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods; D010902:Pituitary Gland / Q000032:analysis*; D010920:Placenta / Q000032:analysis; D011863:Radioimmunoassay / Q000379:methods; D011869:Radioligand Assay / Q000379:methods; D014070:Tooth / Q000032:analysis
chemical_list: D004723:Endorphins