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Analysis of Protein Binding by Fluorescence recovery after photobleaching (FRAP) (CAT#: STEM-MT-0002-WXH)

Introduction

Protein binding can involve plasma proteins, extracellular tissue proteins, or intracellular tissue proteins. Many drugs in circulation are bound to plasma proteins, and because bound drug is too large to pass through biologic membranes, only free drug is available for delivery to the tissues and to produce the desired pharmacologic action. Therefore the degree of protein binding can greatly affect the pharmacokinetics of drugs.




Principle

Fluorescence recovery after photobleaching (FRAP) is a microscopy technique capable of quantifying the mobility of molecules within cells. By exploiting the phenomenon of photobleaching, fluorescent mole- cules within a region of interest can be selectively and irreversibly 'turned off'. It is capable of quantifying the two-dimensional lateral diffusion of a molecularly thin film containing fluorescently labeled probes, or to examine single cells.

Applications

• Characterization of the mobility of individual lipid molecules within a cell membrane.
• Analysis of molecule diffusion within the cell
• Study of protein interaction partners, organelle continuity and protein trafficking.

Procedure

1. An initial fluorescence of fluorescent molecules is measured in the region of interest (ROI).
2. The fluorescent molecules are rapidly photobleached by focusing the high-intensity laser beam onto the defined area.
3. The exchange of bleached molecules with unbleached molecules from the surrounding region is followed over time using a low-intensity laser.

Materials

• Optical microscope.
• Light source.
• Fluorescent probe.