title: Deletion of the carboxy terminal part of stefin B does not have a major effect for binding to papain.
abstract: Determination of crystal structures of chicken cystatin and human stefin B complexed with papain revealed a novel model of protease inhibition and also structural differences between two cysteine proteinase inhibitor (CPI) families. According to the 3D alignment, stefins have an extension of 9 amino acids on their carboxy terminus in comparison with cystatins. The extension was not expected to make a major contribution to interaction with the enzyme. A deletion mutant of stefin B, corresponding in length to the carboxy terminal sequence of chicken cystatin, was constructed by the use of polymerase chain reaction (PCR). This (C3S, delta 89-98) human stefin B, 10 amino acids shorter, inhibited papain with a Ki of 0.012 nM which is comparable to the Ki of 0.03 nM for authentic, nondeleted recombinant stefin B. This finding thus confirms the tertiary structure-based alignment.
authors.affiliation: Department of Biochemistry, Jozef Stefan Institute, Ljubljana, Yugoslavia.
authors.forename: R
authors.initials: R
authors.lastname: Jerala
authors.forename: L
authors.initials: L
authors.lastname: Kroon-Zitko
authors.forename: M
authors.initials: M
authors.lastname: Kopitar
authors.forename: T
authors.initials: T
authors.lastname: Popovic
authors.forename: V
authors.initials: V
authors.lastname: Turk
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002872:Chromosome Deletion; D055313:Cystatin B; D015891:Cystatins / Q000235:genetics / Q000378:metabolism*; D004247:DNA / Q000235:genetics; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D008969:Molecular Sequence Data; D009154:Mutation; D010206:Papain / Q000378:metabolism*; D013329:Structure-Activity Relationship
chemical_list: C524994:CSTB protein, human; D015891:Cystatins; D055313:Cystatin B; D004247:DNA; D010206:Papain