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Fluorescence-based protein footprinting using histidine-tagged protein
1National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
Biotechniques
|February 10, 1998
Summary
This study introduces a protein footprinting method using histidine tags and protease digestion to map ligand-binding sites on proteins. This technique identifies DNA-protein interaction sites protected from enzymatic cleavage.
Area of Science:
- Biochemistry
- Molecular Biology
- Proteomics
Background:
- Identifying protein-ligand interaction sites is crucial for understanding biological processes.
- Existing methods may have limitations in resolution or scope.
- Protein footprinting offers a way to map these interactions directly.
Purpose of the Study:
- To develop and present a novel protein footprinting procedure.
- To identify specific regions of proteins that interact with ligands, such as DNA.
- To validate the method's applicability in detecting direct and allosteric binding sites.
Main Methods:
- Utilizing a histidine-tagged protein for affinity purification on metal-chelated resin.
- Performing limited protease digestion to generate protein fragments.
- Separating histidine-tagged fragments, labeling them with a fluorescein derivative.
- Analyzing labeled peptides via denaturing polyacrylamide gel electrophoresis and FluorImager visualization.
Main Results:
- Successfully identified protease target sites protected from digestion due to ligand (DNA) interaction.
- Demonstrated the ability to resolve and visualize labeled digestion products.
- Established a method for mapping protein regions involved in ligand binding.
Conclusions:
- The described protein footprinting technique effectively maps ligand-binding interfaces.
- The method is applicable for identifying direct contact sites and allosterically affected regions.
- This approach provides valuable insights into protein-ligand interactions.