title: Specific degradation of H. pylori urease by a catalytic antibody light chain.
abstract: Catalytic antibodies capable of digesting crucial proteins of pathogenic bacteria have long been sought for potential therapeutic use. Helicobacter pylori urease plays a crucial role for the survival of this bacterium in the highly acidic conditions of human stomach. The HpU-9 monoclonal antibody (mAb) raised against H. pylori urease recognized the alpha-subunit of the urease, but only slightly recognized the beta-subunit. However, when isolated both the light and the heavy chains of this antibody were mostly bound to the beta-subunit. The cleavage reaction catalyzed by HpU-9 light chain (HpU-9-L) followed the Michaelis-Menten equation with a K(m) of 1.6 x 10(-5) m and a k(cat) of 0.11 min(-1), suggesting that the cleavage reaction was enzymatic. In a cleavage test using H. pylori urease, HpU-9-L efficiently cleaved the beta-subunit but not the alpha-subunit, indicating that the degradation by HpU-9-L had a specificity. The cleaved peptide bonds in the beta-subunit were L121-A122, E124-G125, S229-A230, Y241-D242, and M262-A263. BSA was hardly cleaved by HpU-9-L, again indicating the digestion by HpU-9-L was specific. In summary, we succeeded in the preparation of a catalytic antibody light chain capable of specifically digesting the beta-subunit of H. pylori urease.
authors.affiliation: Prefectural University of Hiroshima, Faculty of Bioscience and Environment, Hiroshima, Japan.
authors.forename: Emi
authors.initials: E
authors.lastname: Hifumi
authors.forename: Kenji
authors.initials: K
authors.lastname: Hatiuchi
authors.forename: Takuro
authors.initials: T
authors.lastname: Okuda
authors.forename: Akira
authors.initials: A
authors.lastname: Nishizono
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Okamura
authors.forename: Taizo
authors.initials: T
authors.lastname: Uda
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017151:Antibodies, Catalytic / Q000378:metabolism*; D000911:Antibodies, Monoclonal / Q000378:metabolism; D001665:Binding Sites; D016480:Helicobacter pylori / Q000201:enzymology* / Q000235:genetics / Q000276:immunology*; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D021122:Protein Subunits; D014510:Urease / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*
chemical_list: D017151:Antibodies, Catalytic; D000911:Antibodies, Monoclonal; D010446:Peptide Fragments; D021122:Protein Subunits; D014510:Urease