Purification and characterization of endoproteases from human choroid plexus cleaving prodynorphin-derived opioid...

An endoprotease converting the dynorphins and alpha-neoendorphin has been purified to apparent homogeneity from soluble extracts of human choroid plexus. The purified enzyme was stained as a single band after sodium dodecyl sulphate polyacrylamide gel electrophoresis with an apparent molecular weight of around 54,000 Da. The enzyme potently cleaves dynorphin A, dynorphin B and alpha-neoendorphin at consecutive pairs of basic amino acid residues generating Leu-Enk-Arg6, but it is less active on other neuropeptides containing dibasic stretches. It is optimally active at neutral pH, sensitive to EDTA and slightly affected by the serine protease inhibitors DFP and PMSF. A similar membrane-bound enzyme present in the same tissue was solubilized with 0.5% Triton X-100 and isolated with the same purification procedure. This latter enzyme showed almost identical properties with the soluble peptidase, except for a slightly higher molecular weight.