Cerebrocystatin suppresses degradation of myelin basic protein by purified brain cysteine proteinase.
Procedures are described for extraction or release, assay and purification of cerebrocystatin an inhibitor of brain cathepsin B or of papain. Neurosecretory regions of rat brain contained significantly higher amounts of cerebrocystatin compared to cortex, cerebellum, mid- and lower brain regions, and spinal cord. Inhibitor was purified to apparent homogeneity by alkaline treatment of rat brain cytosol, followed by gel-filtration and affinity chromatography on Reacti-gel coupled to alkylated papain. Purified cerebrocystatin was a single polypeptide of Mr 12,500 as shown by gel-electrophoresis on urea-SDS slab gels. Cerebrocystatin inhibited the hydrolysis of BANA by papain (Ki, 1 nM) or by purified rat brain cathepsin B (Ki, 10 nM) and suppressed the hydrolysis of myelin basic protein (MBP) by cathepsin B (I50, 0.8 microM) and prevented its cleavage to form polypeptides of Mr 15,000-17,000.
D000818:Animals; D001923:Brain Chemistry; D002417:Cattle; D003546:Cysteine Endopeptidases; D003600:Cytosol / Q000378:metabolism*; D004676:Myelin Basic Protein / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000302:isolation & purification / Q000494:pharmacology*; D011480:Protease Inhibitors; D051381:Rats
D004676:Myelin Basic Protein; D009419:Nerve Tissue Proteins; D011480:Protease Inhibitors; C037791:cerebrocystatin; D003546:Cysteine Endopeptidases