title: Biochemical characterization of cathepsin D from the mussel Lamellidens corrianus.
abstract: A lysosomal cathepsin D (EC 3.4.23.5) was purified to homogeneity from the soft tissues of the fresh water mussel (Lamellidens corrianus) by pepstatin A affinity chromatography. The purified enzyme is a glycoprotein and migrates as a single protein species in native PAGE and shows a single band in SDS-PAGE corresponding to a molecular mass of ~43 kDa. Under both these conditions cathepsin D hydrolyzes hemoglobin as shown by zymogram analysis. The purified enzyme cross-reacts with an antiserum to purified starfish (Asterias rubens) cathepsin D. Additionally, the enzyme was recognized by the starfish lysosomal enzyme targeting receptors (mannose 6-phosphate receptors: MPR 300 and 46) in ligand blot analysis. The KM value of the purified enzyme with hemoglobin is 1.5mM. pH and temperature optimum for the enzyme are 3.5 and 60 °C respectively.
authors.affiliation: Protein Biochemistry and Glycobiology Laboratory, Department of Biochemistry, University of Hyderabad, Hyderabad 500046, India.
authors.forename: Ashapogu
authors.initials: A
authors.lastname: Venugopal
authors.affiliation: Protein Biochemistry and Glycobiology Laboratory, Department of Biochemistry, University of Hyderabad, Hyderabad 500046, India. Electronic address: nsksl@uohyd.ernet.in.
authors.forename: Nadimpalli
authors.initials: N
authors.lastname: Siva Kumar
mesh_terms: D000818:Animals; D049872:Bivalvia / Q000201:enzymology*; D002402:Cathepsin D / Q000737:chemistry*; D008247:Lysosomes / Q000201:enzymology; D017527:Receptor, IGF Type 2 / Q000737:chemistry
chemical_list: D017527:Receptor, IGF Type 2; D002402:Cathepsin D
keywords: 5-bromo-4-chloro-3′-indolyl phosphate; BCIP; Cathepsin D; ECL; Hb; IU; Invertebrate; Lamellidens corrianus; MPR; Mannose 6-phosphate receptor; NBT; PBST; TCA; Zymogram; enhanced chemiluminescence; hemoglobin; international unit; mannose 6-phosphate receptor; nitro blue tetrazolium chloride; phosphate-buffered saline containing Tween 20; trichloroacetic acid