Preparative and analytical capillary zone electrophoresis analysis of native endorphins and enkephalins extracted from the bovine pituitary: mass spectrometric confirmation of the molecular mass of leucine enkephalin.
One proopiomelanocortin peptide [beta-endorphin (BE)] and two proenkephalin A peptides [methionine enkephalin (ME) and leucine enkephalin (LE); LE derives also from proenkephalin B] were searched for in a bovine pituitary extract by capillary zone electrophoresis (CZE) and liquid secondary-ion mass spectrometry (LSIMS). A bovine pituitary homogenate was subjected to acid precipitation/centrifugation and solid-phase extraction of peptides using an octadecyl-silyl disposable cartridge. The peptide-enriched fraction was subjected to CZE at pH 2.5 and at pH 5.5., and fractions were collected under preparative CZE conditions within defined time windows where synthetic BE, ME, and LE migrate. The resolving power of CZE was demonstrated by collecting biological fractions at pH 5.5 under preparative conditions and by subsequently analyzing these fractions at pH 2.5 under analytical conditions. Preparative CZE was further performed at pH 2.5 for fractions collected at pH 5.5. LSIMS analysis of this second-dimensional CZE fraction revealed the appropriate protonated molecule ion [(M + H)+, m/z 556.4] of LE.
D000818:Animals; D002197:Capillary Action; D002417:Cattle; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004586:Electrophoresis / Q000379:methods; D004723:Endorphins / Q000032:analysis* / Q000302:isolation & purification; D004744:Enkephalin, Methionine / Q000032:analysis; D004745:Enkephalins / Q000032:analysis* / Q000302:isolation & purification; D008970:Molecular Weight; D009479:Neuropeptides / Q000032:analysis; D010902:Pituitary Gland / Q000737:chemistry*; D018629:Spectrometry, Mass, Secondary Ion / Q000379:methods; D001615:beta-Endorphin / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification
D004723:Endorphins; D004745:Enkephalins; D009479:Neuropeptides; D004744:Enkephalin, Methionine; D001615:beta-Endorphin