Detection of analytes using fluorescence energy transfer

摘要

The invention provides labeled proteins suitable for determining the presence of cAMP, other second messengers and organic molecules. The proteins are separately labeled with fluorochromes which, when in close spatial proximity, preferably, less than about 6 nm, interact through the transfer of energy from one fluorochrome to the other. A composition of matter (S1kA)n1(S2kD)n2 is provided wherein S1 and S2 are two proteins which are associated in one state and substantially disassociated in another, the equilibrium between which is controlled by the free concentration of an analyte, and A and D are fluorochromes, the emission wavelength of fluorochrome D overlapping the excitation wavelength of fluorochrome A and the distance between A and D being in sufficiently close proximity to allow radiationless transfer of energy between the fluorochromes. A and D can be selected from a variety of acceptor, donor pairs such as fluorescein and tetramethylrhodamine.