Related Experiment Video
Updated: May 20, 2026

Fluorescence Anisotropy as a Tool to Study Protein-protein Interactions
Published on: October 21, 2016
Ligand binding induces a sharp decrease in hydrophobicity of folate binding protein assessed by
Jan Holm1, Anders J Lawaetz, Steen I Hansen
1Department of Clinical Biochemistry, Hillerød Hospital, Dyrehavevej 29, DK-3400 Hillerød, Denmark.
Abstract:
High affinity folate binding protein (FBP) regulates as a soluble protein and as a cellular receptor intracellular trafficking of folic acid, a vitamin of great importance to cell growth and division. We addressed two issues of potential importance to the biological function of FBP, a possible decrease of the surface hydrophobicity associated with the ligand-induced conformation change of FBP, and protein-inter-protein interactions involved in self-association of hydrophobic apo-FBP. The extrinsic fluorescent apolar dye 1-anilinonaphthalene-8-sulphonate (ANS) exhibited enhanced fluorescence intensity and a blueshift of emission maximum from 510-520 nm to 460-470 nm upon addition of apo-FBP indicating binding to a strongly hydrophobic environment. Neither enhancement of fluorescence nor blueshift of ANS emission maximum occurred when folate-ligated holo-FBP replaced apo-FBP. The drastic decrease in surface hydrophobicity of holo-FBP could have bearings on the biological function of FBP since changes in surface hydrophobicity have critical effects on the biological function of receptors and transport proteins. ANS interacts with exposed hydrophobic surfaces on proteins and may thereby block and prevent aggregation of proteins (chaperone-like effect). Hence, hydrophobic interactions seemed to participate in the concentration-dependent self-association of apo-FBP which was suppressed by high ANS concentrations in light scatter measurements.
More Related Videos
15:04PeptiQuick, a One-Step Incorporation of Membrane Proteins into Biotinylated Peptidiscs for Streamlined Protein Binding Assays
Published on: November 2, 2019
13:57Bio-layer Interferometry for Measuring Kinetics of Protein-protein Interactions and Allosteric Ligand Effects
Published on: February 18, 2014
Related Concept Videos
Ligand Binding Sites
Protein-ligand interactions are quite specific; even though numerous potential ligands surround a cellular protein at any given time, only a particular ligand can bind to that protein. Moreover, a ligand binds only to a dedicated area on the surface of the protein, known as the...
Factors Affecting Protein-Drug Binding: Protein-Related Factors
The physicochemical properties of a drug play a significant role in its ability to bind to proteins. Lipophilic drugs, which dissolve in fats, oils, and lipids, can be bound by...
Factors Affecting Protein-Drug Binding: Drug-Related Factors
One crucial factor in drug-protein binding is the drug's lipophilicity or its affinity for fat. More lipophilic drugs tend to have higher binding extents. For example, highly lipophilic drugs like cloxacillin exhibit substantial protein binding, with as much as 95% of the drug binding to proteins. In contrast,...
Ligand Binding and Linkage
The Equilibrium Binding Constant and Binding Strength
Factors Affecting Protein-Drug Binding: Drug Interactions
Displacement interactions can have varying outcomes, ranging from toxicity to virtually...