title: Purification and characterization of cystatin from duck egg white.
abstract: It is the second peptidase inhibitor, after ovostatin, which showing the same antipapain activity in egg white in different avian species implies differences in amino-acid sequences. Cystatin from duck egg white was purified by carboxymethylpapain affinity chromatography and size-exclusion HPLC. The purified inhibitor which showed partial identity in the immunodiffusion test with chicken egg white cystatin, had an apparent molecular mass of 9.3 kDa as determined by SDS/PAGE. IEF analysis revealed five molecular forms of pI in the range 7.8-8.4. The obtained cystatin was neither glycosylated nor phosphorylated as it is in the case of chicken cystatin. The determined Ki (0.005 +/- 0.001 nM) was similar to that reported for human and chicken cystatin C.
authors.affiliation: Department of Pharmaceutical Biochemistry, Medical Academy, Wrocław, Poland.
authors.forename: M
authors.initials: M
authors.lastname: Warwas
authors.forename: J
authors.initials: J
authors.lastname: Gburek
authors.forename: J
authors.initials: J
authors.lastname: Osada
authors.forename: K
authors.initials: K
authors.lastname: Gołab
mesh_terms: D000818:Animals; D002645:Chickens; D015891:Cystatins / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification*; D015853:Cysteine Proteinase Inhibitors / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification*; D004372:Ducks / Q000378:metabolism*; D005260:Female; D006031:Glycosylation; D006801:Humans; D007120:Immunochemistry; D007526:Isoelectric Point; D008970:Molecular Weight; D010063:Ovum / Q000737:chemistry*; D010206:Papain / Q000037:antagonists & inhibitors; D010766:Phosphorylation; D013045:Species Specificity
chemical_list: D015891:Cystatins; D015853:Cysteine Proteinase Inhibitors; D010206:Papain