title: Dipeptidyl peptidase III of human cataractous lenses. Partial purification.
abstract: A partial purification of dipeptidyl peptidase III has been achieved from human cataractous lens. The specific activity was increased 45.5-fold over that of the original aqueous extract. The exopeptidase exhibited a marked preference for the release of Arg-Arg from Arg-Arg-2-NNap at the optimum pH 8.8 and 37 degrees. The Km for this substrate was estimated to be 6.061 X 10(-3). Lens DPP III was inhibited by EDTA, p-chloromercuriphenyl sulfonate, puromycin and DFP. The preparation contained leucyl aminopeptidase and a neutral endopeptidase as contaminating proteases.
mesh_terms: D002386:Cataract / Q000201:enzymology*; D011232:Chemical Precipitation; D003459:Crystallins / Q000032:analysis; D004151:Dipeptides / Q000378:metabolism; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000032:analysis* / Q000302:isolation & purification; D010450:Endopeptidases / Q000032:analysis*; D006358:Hot Temperature; D006801:Humans; D006868:Hydrolysis; D007908:Lens, Crystalline / Q000201:enzymology*
chemical_list: D003459:Crystallins; D004151:Dipeptides; C040852:arginylarginine 2-naphthylamide; D010450:Endopeptidases; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases