title: Purification, characterization and kinetics of thiol protease inhibitor from goat (Capra hircus) lung.
abstract: In the present study, two molecular forms of goat lung cystatin (GLC), I and II, were purified to homogeneity by a two-step procedure including ammonium sulfate precipitation (40-60%) and ion exchange chromatography. The inhibitor forms migrated as single bands under native and SDS-PAGE with and without reducing agent giving molecular mass of 66.4 and 76.4 kDa, respectively. GLC-I possesses 0.07% and GLC-II 2.3% carbohydrate content and no -SH groups. GLC-I showed greater affinity for papain than for ficin and bromelain. Immunological studies showed that the inhibitor was pure and there was cross reactivity between anti-GLC-I serum and goat brain cystatin. Both inhibitor forms were stable in the pH range of 3-10 and up to 75 degrees C. GLC-I was found to possess 49% alpha-helical structure by CD spectroscopy. The inhibitor-papain complexes showed conformational changes as invoked by UV and fluorescence spectroscopic studies.
authors.affiliation: Department of Biochemistry, Faculty of Life Sciences, Aligarh Muslim University, Aligarh, 202002, India.
authors.forename: Mohd Shahnawaz
authors.initials: MS
authors.lastname: Khan
authors.forename: Bilqees
authors.initials: B
authors.lastname: Bano
mesh_terms: D000818:Animals; D015891:Cystatins / Q000737:chemistry* / Q000302:isolation & purification* / Q000378:metabolism; D015853:Cysteine Proteinase Inhibitors / Q000737:chemistry* / Q000302:isolation & purification* / Q000378:metabolism; D006041:Goats / Q000378:metabolism*; D007700:Kinetics; D008168:Lung / Q000737:chemistry* / Q000378:metabolism; D008970:Molecular Weight; D055550:Protein Stability
chemical_list: D015891:Cystatins; D015853:Cysteine Proteinase Inhibitors