Dual Beneficial Effect of Interloop Disulfide Bond for Single Domain Antibody Fragments

• DOI: 10.1074/jbc.m111.242818
• Publication Date: 2011-12-01T12:34:02Z
• Authors: Jochen Govaert; Mireille Pellis; Nick Deschacht; Cécile Vincke; Katja Conrath; Serge Muyldermans; Dirk Saerens
• Keywords: Single-domain antibody

The antigen-binding fragment of functional heavy chain antibodies (HCAbs) in camelids comprises a single domain, named the variable domain HCAbs (VHH). VHH harbors remarkable amino acid substitutions framework region-2 to generate an that functions absence light partner. provide more hydrophilic, hence soluble, character but decrease intrinsic stability domain. Here we investigate role additional hallmark dromedary VHHs, i.e. extra disulfide bond between first and third loops. After substituting cysteines forming this interloop cystine by all 20 acids, selected characterized several VHHs retain antigen binding capacity. Although domains can function bond, demonstrate its presence constitutes net advantage. First, stabilizes counteracts destabilization acids. Second, rigidifies long loop, leading stronger interaction. This dual beneficial effect explains vivo antibody maturation process favoring with bond.