The measurement of free fatty acid concentration with the fluorescent probe ADIFAB: A practical guide for the use of the ADIFAB probe

The aqueous phase monomers of fatty acids (FFA) appear in many steps of fat metabolism. Understanding metabolism requires that accurate measurements o f FFA levels be determined in enzyme-mediated as well as in membrane and pr otein binding reactions. Measuring long chain FFA levels with sufficient se nsitivity and temporal resolution is now possible using fluorescent probes constructed by ligating fluorescent groups and fatty acid binding proteins. In this paper we provide a practical description of the use of ADIFAB, the acrylodan labeled intestinal fatty acid binding protein. We describe with specific examples how ADIFAB can be used to determine, (1) FFA concentratio ns in aqueous solutions, (2) binding affinities of fatty acid binding prote ins, (3) membrane/water partition coefficients, (4) lipase activities, and (5) serum levels of FFA.