title: Structure-activity relationship in buffalo spleen cathepsin B.
abstract: Effect of pH, urea, and guanidine hydrochloride on the activity and structure of buffalo spleen cathepsin B was investigated. At alkaline pH, there was an irreversible loss of the structure as well as the activity of the buffalo enzyme. At acidic pH, however, the inactivation of the enzyme was reversible. The enzyme reversibly lost most of its activity at denaturant concentrations which did not cause a significant change in its secondary structure. The inactivation could be attributed to minor perturbations in the environment of the amino acid residue(s) at and/or around the active site of the enzyme. High urea/guanidine hydrochloride concentrations leading to the structural changes in cathepsin B made the inactivation process irreversible.
authors.affiliation: Department of Biochemistry, School of Life Sciences, North-Eastern Hill University, Shillong, India.
authors.forename: M Y
authors.initials: MY
authors.lastname: Khan
authors.forename: S K
authors.initials: SK
authors.lastname: Agarwal
authors.forename: S
authors.initials: S
authors.lastname: Ahmad
mesh_terms: D000818:Animals; D001665:Binding Sites; D002020:Buffaloes; D002401:Cathepsin B / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D019791:Guanidine; D006146:Guanidines / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D011487:Protein Conformation / Q000187:drug effects; D013154:Spleen / Q000201:enzymology; D013329:Structure-Activity Relationship; D014508:Urea / Q000494:pharmacology
chemical_list: D006146:Guanidines; D014508:Urea; D002401:Cathepsin B; D019791:Guanidine