title: Characterisation of xenopsin immunoreactivity derived from pepsinised human skin and possible mechanism of in vivo generation.
abstract: Human skin was subjected to a variety of extraction and enzymatic digestion procedures. Extracts and digests were subjected to neurotensin and xenopsin radioimmunoassays of known specificity. No neurotensin immunoreactivity was detected in any preparation with any region-specific antiserum. C-terminal xenopsin immunoreactivity was present in skin homogenates following incubation with both soluble and solid-phase pepsin and in those incubated with a leucocyte lysate or purified cathepsin D. The generation of xenopsin immunoreactivity was dependent on low pH and enzymes of pepsin-type specificity acting on a tissue precursor of approximately 30 kDa. Gel permeation chromatography of skin-derived xenopsin immunoreactivity identified a single molecular species larger than synthetic xenopsin which was resolved into two components by reverse-phase HPLC with retention times similar to synthetic xenopsin and kinetensin. Human skin thus contains a high-molecular-weight precursor protein and an endogenous acid protease, cathepsin D, capable of generating a peptide of similar size and C-terminal structure to amphibian xenopsin under acidic conditions such as might occur locally in wounds or at sites of inflammation.
authors.affiliation: Department of Medicine, Queen's University of Belfast, Northern Ireland.
authors.forename: D J
authors.initials: DJ
authors.lastname: Eedy
authors.forename: C
authors.initials: C
authors.lastname: Shaw
authors.forename: C F
authors.initials: CF
authors.lastname: Johnston
authors.forename: K D
authors.initials: KD
authors.lastname: Buchanan
mesh_terms: D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009496:Neurotensin / Q000276:immunology; D009842:Oligopeptides / Q000096:biosynthesis / Q000276:immunology / Q000302:isolation & purification*; D010434:Pepsin A / Q000494:pharmacology; D010455:Peptides; D011498:Protein Precursors / Q000276:immunology / Q000302:isolation & purification; D011863:Radioimmunoassay; D012867:Skin / Q000032:analysis* / Q000276:immunology / Q000378:metabolism; D012995:Solubility; D014020:Tissue Extracts; D029867:Xenopus Proteins
chemical_list: D009842:Oligopeptides; D010455:Peptides; D011498:Protein Precursors; D014020:Tissue Extracts; D029867:Xenopus Proteins; D009496:Neurotensin; C016832:xenopsin; D010434:Pepsin A