Degradation of beta-amyloid by proteolytic antibody light chains.
Deposition of beta-amyloid (Abeta) is considered an important early event in the pathogenesis of Alzheimer's disease (AD). Clearance of Abeta thus represents a potential therapeutic approach. Antibody-mediated clearance of Abeta by vaccination inhibited and cleared Abeta deposition in animal models; however, inflammatory side effects were observed in humans. An alternative potentially noninflammatory approach to facilitate clearance is to proteolytically cleave Abeta. We screened 12 proteolytic recombinant antibody fragments for potential alpha-secretase activity, a naturally occurring enzyme that cleaves between the Lys16 and Leu17 residues of the amyloid precursor protein (APP). We utilized the synthetic alpha-secretase substrate, benzyloxycarbonyl-l-lysine o-nitrophenyl ester (Z-lys-o-Np) as a preliminary screen for alpha-secretase activity. Two antibody light chain fragments that hydrolyzed Z-lys-o-Np were identified. Abeta hydrolysis was studied using mass spectrometry to identify the cleavage patterns of the antibodies. The recombinant antibody light chain antibody fragment, c23.5, showed alpha-secretase-like activity, producing the 1-16 and 17-40 amino acid fragments of Abeta. The second light chain antibody fragment, hk14, demonstrated carboxypeptidase-like activity, cleaving sequentially from the carboxyl terminal of Abeta. These antibody light chains provide a novel route toward engineering efficient therapeutic antibodies capable of cleaving Abeta in vivo.
Rangan
Srinath Kasturi
SK
Department of Chemical and Materials Engineering, Arizona State University, Tempe, Arizona 85287, USA.
Liu
Ruitian
R
Brune
Daniel
D
Planque
Stephanie
S
Paul
Sudhir
S
Sierks
Michael R
MR
D000544:Alzheimer Disease / Q000378:metabolism; D053829:Amyloid Precursor Protein Secretases; D016229:Amyloid beta-Peptides / Q000276:immunology / Q000378:metabolism*; D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism; D016282:Aspartic Acid Endopeptidases; D002268:Carboxypeptidases / Q000276:immunology / Q000378:metabolism; D002384:Catalysis; D002863:Chromogenic Compounds / Q000378:metabolism; D010450:Endopeptidases / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D006868:Hydrolysis; D007128:Immunoglobulin Fragments / Q000378:metabolism; D007147:Immunoglobulin Light Chains / Q000378:metabolism*; D007700:Kinetics; D008239:Lysine / Q000031:analogs & derivatives* / Q000378:metabolism; D013058:Mass Spectrometry; D051379:Mice; D010446:Peptide Fragments / Q000276:immunology / Q000378:metabolism*; D013379:Substrate Specificity
D016229:Amyloid beta-Peptides; D000911:Antibodies, Monoclonal; D002863:Chromogenic Compounds; D007128:Immunoglobulin Fragments; D007147:Immunoglobulin Light Chains; D010446:Peptide Fragments; C084358:amyloid beta-protein (1-28); C055966:immunoglobulin Fv; C034117:N-benzyloxycarbonyllysine 4-nitrophenyl ester; D053829:Amyloid Precursor Protein Secretases; D002268:Carboxypeptidases; D010450:Endopeptidases; D016282:Aspartic Acid Endopeptidases; C509280:BACE1 protein, human; C509282:Bace1 protein, mouse; D008239:Lysine