Dynamic Strength of the Interaction between Lung Surfactant Protein D (SP-D) and Saccharide Ligands

In order to investigate the dynamic strength of the interaction between lung surfactant protein D (SP-D) and different sugars, maltose, mannose, glucose, and galactose, we have used an atomic force microscope to monitor the interaction on a single molecule scale. The experiment is performed by measu...

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Veröffentlicht in:Biochemistry (Easton) 2007-10, Vol.46 (43), p.12231-12237
Hauptverfasser: Thormann, Esben, Dreyer, Jakob K., Simonsen, Adam C., Hansen, Per L., Hansen, Søren, Holmskov, Uffe, Mouritsen, Ole G.
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Sprache:eng
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Zusammenfassung:In order to investigate the dynamic strength of the interaction between lung surfactant protein D (SP-D) and different sugars, maltose, mannose, glucose, and galactose, we have used an atomic force microscope to monitor the interaction on a single molecule scale. The experiment is performed by measuring the rupture force when the SP-D−sugar bond is subjected to a continuously increasing force. Under these dynamic conditions, SP-D binds strongest to d-mannose and weakest to maltose and d-galactose. These results differ from equilibrium measurements wherein SP-D exhibits preference for maltose. On the basis of this finding, we propose that the binding of the disaccharide maltose to SP-D, which is energetically stronger than the binding of any of the monosacchrides, alters the structure of the binding site in a way that lowers the dynamic strength of the bond. We conclude that determining the strength of a protein−ligand bond under dynamic stress using an atomic force microscope is possibly more relevant for mimicking the actual nonequilibrium physiological situation in the lungs.
ISSN:0006-2960
1520-4995
DOI:10.1021/bi700823k