title: Basis for selection of improved carbohydrate-binding single-chain antibodies from synthetic gene libraries.
abstract: A technique is described for the simultaneous and controlled random mutation of all three heavy or light chain complementarity-determining regions (CDRs) in a single-chain Fv specific for the O polysaccharide of Salmonella serogroup B. Sense oligonucleotides were synthesized such that the central bases encoding a CDR were randomized by equimolar spiking with A, G, C, and T at a level of 10% while the antisense strands contained inosine in the spiked regions. Phage display of libraries assembled from the spiked oligonucleotides by a synthetic ligase chain reaction demonstrated a bias for selection of mutants that formed dimers and higher oligomers. Kinetic analyses showed that oligomerization increased association rates in addition to slowing dissociation rates. In combination with some contribution from reduced steric clashes with residues in heavy-chain CDR2, oligomerization resulted in functional affinities that were much higher than that of the monomeric form of the wild-type single-chain Fv.
authors.affiliation: Institute for Biological Sciences, National Research Council of Canada, Ottawa, ON.
authors.forename: S J
authors.initials: SJ
authors.lastname: Deng
authors.forename: C R
authors.initials: CR
authors.lastname: MacKenzie
authors.forename: T
authors.initials: T
authors.lastname: Hirama
authors.forename: R
authors.initials: R
authors.lastname: Brousseau
authors.forename: T L
authors.initials: TL
authors.lastname: Lowary
authors.forename: N M
authors.initials: NM
authors.lastname: Young
authors.forename: D R
authors.initials: DR
authors.lastname: Bundle
authors.forename: S A
authors.initials: SA
authors.lastname: Narang
mesh_terms: D000595:Amino Acid Sequence; D000906:Antibodies / Q000737:chemistry* / Q000276:immunology; D000907:Antibodies, Bacterial / Q000096:biosynthesis* / Q000737:chemistry* / Q000276:immunology; D001666:Binding Sites, Antibody; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002241:Carbohydrates; D003001:Cloning, Molecular; D004926:Escherichia coli; D015723:Gene Library; D005813:Genes, Synthetic; D007700:Kinetics; D046911:Macromolecular Substances; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016296:Mutagenesis; D016297:Mutagenesis, Site-Directed; D019081:O Antigens; D009844:Oligosaccharides / Q000737:chemistry / Q000378:metabolism; D011135:Polysaccharides, Bacterial / Q000276:immunology*; D017433:Protein Structure, Secondary; D011897:Random Allocation; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000276:immunology; D015183:Restriction Mapping; D012475:Salmonella / Q000276:immunology; D013329:Structure-Activity Relationship
chemical_list: D000906:Antibodies; D000907:Antibodies, Bacterial; D002241:Carbohydrates; D046911:Macromolecular Substances; D019081:O Antigens; D009844:Oligosaccharides; D011135:Polysaccharides, Bacterial; D011994:Recombinant Proteins