Patent ID: 8206941

Claim:
A method for determining kinase activity comprising: a) providing: i) a substrate molecule that can be phosphorylated by a kinase wherein said substrate molecule is labeled with an energy donor of a fluorescence resonance energy transfer (FRET) pair; ii) a detection molecule labeled with an energy acceptor of the fluorescence resonance energy transfer (FRET) pair, and iii) a binding partner which binds to both the phosphorylated substrate molecule and to the detection molecule, but does not bind to the unphosphorylated substrate molecule; b) phosphorylating the labeled substrate molecule with a kinase; c) combining said labeled, phosphorylated substrate molecule, said labeled detection molecule, and said binding partner such that both of said phosphorylated substrate molecule and said detection molecule bind to said binding partner d) determining kinase activity by measuring energy transfer from the energy donor of said labeled substrate molecule to the energy acceptor of said labeled detection molecule while both are bound to said binding partner, wherein the energy donor has an emission lifetime of less than 10 microseconds.