1g6v
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Complex of the camelid heavy-chain antibody fragment CAB-CA05 with bovine carbonic anhydrase
OverviewOverview
Detailed knowledge on antibody-antigen recognition is scarce given the, unlimited antibody specificities of which only few have been investigated, at an atomic level. We report the crystal structures of an antibody, fragment derived from a camel heavy chain antibody against carbonic, anhydrase, free and in complex with antigen. Surprisingly, this, single-domain antibody interacts with nanomolar affinity with the antigen, through its third hypervariable loop (19 amino acids long), providing a, flat interacting surface of 620 A(2). For the first time, a single-domain, antibody is observed with its first hypervariable loop adopting a type-1, canonical structure. The second hypervariable loop, of unique size due to, a somatic mutation, reveals a regular beta-turn. The third hypervariable, loop covers the remaining hypervariable loops and the side of the domain, that normally interacts with the variable domain of the light chain., Specific amino acid substitutions and reoriented side chains reshape this, side of the domain and increase its hydrophilicity. Of interest is the, substitution of the conserved Trp-103 by Arg because it opens new, perspectives to 'humanize' a camel variable domain of heavy chain of heavy, chain antibody (VHH) or to 'camelize' a human or a mouse variable domain, of heavy chain of conventional antibody (VH).
About this StructureAbout this Structure
1G6V is a Single protein structure of sequence from Bos taurus and Camelus dromedarius with as ligand. Active as Carbonate dehydratase, with EC number 4.2.1.1 Full crystallographic information is available from OCA.
ReferenceReference
Antigen specificity and high affinity binding provided by one single loop of a camel single-domain antibody., Desmyter A, Decanniere K, Muyldermans S, Wyns L, J Biol Chem. 2001 Jul 13;276(28):26285-90. Epub 2001 May 7. PMID:11342547
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