Recognition of a Cell-Surface Oligosaccharide of Pathogenic Salmonella by an Antibody Fab Fragment

M Cygler, DR Rose, DR Bundle - Science, 1991 - science.org
M Cygler, DR Rose, DR Bundle
Science, 1991science.org
The 2.05 angstrom (Å) resolution crystal structure of a dodecasaccharide-Fab complex
revealed an unusual carbohydrate recognition site, defined by aromatic amino acids and a
structured water molecule, rather than the carboxylic acid and amide side chains that are
features of transport and other carbohydrate binding proteins. A trisaccharide epitope of a
branched bacterial lipopolysaccharide fills this hydrophobic pocket (8 Å deep by 7 Å wide) in
an entropy-assisted association (association constant= 2.05× 105 liters per mole, enthalpy …
The 2.05 angstrom (Å) resolution crystal structure of a dodecasaccharide-Fab complex revealed an unusual carbohydrate recognition site, defined by aromatic amino acids and a structured water molecule, rather than the carboxylic acid and amide side chains that are features of transport and other carbohydrate binding proteins. A trisaccharide epitope of a branched bacterial lipopolysaccharide fills this hydrophobic pocket (8 Å deep by 7 Å wide) in an entropy-assisted association (association constant = 2.05 × 105 liters per mole, enthalpy = -20.5 ± 1.7 kilojoules per mole, and temperature times entropy = +10.0 ± 2.9 kilojoules per mole). The requirement for the complementarity of van der Waals surfaces and the requirements of saccharide-saccharide and protein-saccharide hydrogen-bonding networks determine the antigen conformation adopted in the bound state.
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