1. Degradation of beta-amyloid by proteolytic antibody light chains.
- Author
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Rangan SK, Liu R, Brune D, Planque S, Paul S, and Sierks MR
- Subjects
- Alzheimer Disease metabolism, Amyloid Precursor Protein Secretases, Amyloid beta-Peptides immunology, Animals, Antibodies, Monoclonal metabolism, Aspartic Acid Endopeptidases, Carboxypeptidases immunology, Carboxypeptidases metabolism, Catalysis, Chromogenic Compounds metabolism, Endopeptidases immunology, Humans, Hydrolysis, Immunoglobulin Fragments metabolism, Kinetics, Lysine metabolism, Mass Spectrometry, Mice, Peptide Fragments immunology, Substrate Specificity, Amyloid beta-Peptides metabolism, Endopeptidases metabolism, Immunoglobulin Light Chains metabolism, Lysine analogs & derivatives, Peptide Fragments metabolism
- Abstract
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.
- Published
- 2003
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