Purification, subunit structure and inhibitor profile of cathepsin A.
Cathepsin A (EC 3.4.16.1), a lysosomal carboxypeptidase, has been purified 1374-fold from pig kidney. Purification steps included concanavalin A-Sepharose and phenyl-Sepharose chromatography and chromatofocusing. The specific activity (16.9 U/mg) of the purified enzyme was significantly higher than previously reported values. The enzyme preparation appeared homogeneous when analyzed by non-denaturing polyacrylamide gel electrophoresis and was free of detectable protease contamination. The molecular mass (M(r) = 97,000), isoelectric point (5.0), and sensitivity to inhibitors were consistent with reported properties of cathepsin A. However, the previously reported three-peptide chain structure was not observed. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the presence or absence of 2-mercaptoethanol demonstrated that the enzyme is composed of two M(r) 47,000 subunits, each of which dissociate in the presence of 2-mercaptoethanol into two polypeptide chains of 19,000 and 31,000.
Miller
J J
JJ
Department of Biochemistry, University of Louisville School of Medicine, KY 40292.
Changaris
D G
DG
Levy
R S
RS
D000595:Amino Acid Sequence; D000818:Animals; D002268:Carboxypeptidases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000302:isolation & purification*; D043402:Cathepsin A; D002403:Cathepsins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000302:isolation & purification*; D002845:Chromatography; D003545:Cysteine / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D007668:Kidney / Q000201:enzymology; D008247:Lysosomes / Q000201:enzymology; D008969:Molecular Sequence Data; D008970:Molecular Weight; D013552:Swine
D002268:Carboxypeptidases; D002403:Cathepsins; D043402:Cathepsin A; D003545:Cysteine