title: Isolation and characterization of papaya peptidase A from commercial chymopapain.
abstract: Chromatography on a column of SP-Sephadex shows that commercial chymopapain contains three components with proteolytic activity. Each behaves as a single protein upon rechromatography and electrophoresis on polyacrylamide gels. The major component, which represents 31% of the activity applied to the column and is the most basic protein, was identified as papaya peptidase A. This enzyme has no methionine and isoleucine on its N-terminus. Its molecular weight is about 24,000 as determined by sodium dodecyl sulfate polyacrylamide electrophoresis and sedimentation equilibrium centrifugation. Its fluorescence emission as a function of pH resembles that for unactivated papain. Reduction is required for full activity, and in general it is less active than papain against substrates such as casein, N-benzoyl-L-arginine ethyl ester, N-tosyl-L-arginine methyl ester, N-benzoyl-L-arginineamide, and N-benzoyl-DL-arginine p-nitroanilide. Of the other components isolated from crude chymopapain, the more acidic enzyme contains 20% of the activity applied to the column, has a molecular weight of about 25,000, and N-terminal residues of tyrosine and glutamic acid. The other enzyme represents 26% of the initial activity, has a molecular weight of about 28,000 and tyrosine on its N-terminus. Both proteins have a single residue of methionine per molecule. The more acidic component resembles chymopapain A, and the other enzyme is similar to chymopapain B.
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D002852:Chromatography, Ion Exchange; D002917:Chymopapain / Q000302:isolation & purification*; D004589:Electrophoresis, Disc; D010450:Endopeptidases / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008970:Molecular Weight; D010447:Peptide Hydrolases / Q000302:isolation & purification*; D010944:Plants / Q000201:enzymology; D013050:Spectrometry, Fluorescence; D013329:Structure-Activity Relationship
chemical_list: D000596:Amino Acids; D010450:Endopeptidases; D010447:Peptide Hydrolases; D002917:Chymopapain