Dynorphin-converting enzyme

This chapter presents an overview of the structural chemistry and the biological aspects of Dynorphin-Converting enzyme (DCE). Dynorphins (Dyn) are a class of potent opioid peptides with wide distribution in the nervous system. They are synthesized as large proteins containing biologically active peptides flanked by dibasic and monobasic processing signals. DCE has been purified to homogeneity from the cattle neurointermediate lobe of the pituitary using phenyl-Sepharose hydrophobic chromatography, preparative isoelectrofocusing, nondenaturing electrophoresis and FPLC with Mono-Q (Pharmacia). The enzyme has also been partially purified (about 2,500-fold) from the anterior pituitary. Other sources from which DCE has been partially purified include rat brain and ileum, and cell lines AtT-20, GH4C1 and BRL 2A. The enzyme is present in most tissues, but is particularly abundant in rat brain and pituitary. In tissue homogenates, the activity is equally distributed between soluble and membrane-bound forms. Subcellular fractionation studies have shown that DCE is present in the neuropeptide-containing secretory vesicles in cattle pituitary. DCE is also found in the functional secretory compartment in endocrine cell lines, such as AtT-20 cells and GH4C1 cells.