digitonin and potassium-thiocyanate

The association of endogenous synenkephalin and met-enkephalin containing peptides with the membrane of bovine chromaffin granules and physicochemical characteristics of this association were studied. The associated materials were only released at a non physiological pH range and this effect was enhanced with growing salt concentrations (0.5, 1.0 and 2.0 M KSCN). A higher peptide dissociation occurred with membrane solubilizing agents (SDS greater than Triton X-100 greater than digitonin). In microsomes the materials dissociated with 2 M KSCN (pH 7.4) corresponded to peptides larger than 12.0 kDa, while in granules corresponded to molecules smaller than 8.5 kDa, displaying synenkephalin and met-enkephalin immunoreactivities. These data suggest that some sequence of the C-terminal portion of synenkephalin may be responsible for the association of proenkephalin derived peptides with microsome and granule membranes.

Topics: Adrenal Medulla; Animals; Cattle; Chemical Phenomena; Chemistry, Physical; Chromaffin Granules; Chromatography, Gel; Digitonin; Enkephalin, Methionine; Enkephalins; Hydrogen-Ion Concentration; Intracellular Membranes; Microsomes; Molecular Weight; Octoxynol; Osmolar Concentration; Polyethylene Glycols; Protein Precursors; Sodium Dodecyl Sulfate; Thiocyanates