Patent ID: 7445902
Filing Date: 2008-11-04
Classification: C07H,C09B

Abstract:
1. In a method for a homogeneous fluorescence resonance energy transfer (FRET) assay for measuring binding of a ligand to a GPCR polypeptide, which method comprises the steps of: i) contacting the GPCR polypeptide, which contains a Gα subunit comprising a covalently bound tag and a GTP binding site, with a fluorescent GTPase resistant GTP analogue, wherein said analogue comprises a first fluorescence resonance energy transfer (FRET) label; ii) contacting the GPCR with a detection molecule that comprises a binding moiety that specifically binds to the covalently bound tag and a second FRET label; and measuring the fluorescence intensity resulting from the intramolecular interaction between the first and second FRET labels in the presence and absence of said ligand; wherein an increase in fluorescence intensity is a measure of the potency of ligand binding to the GPCR polypeptide; the improvement comprises: using a compound having the formula hereinbelow as a donor or an acceptor of the FRET assay: wherein: X and Y are the same or different and are selected from >C(CH one of groups R wherein: BASE is a purine base; R′ and R″ are independently H or OH; Z is —O—, —S—, or —NR LiNK is a linking group containing from 1-20 linked carbon atoms which may optionally include one or more groups selected from —NR when any of groups R when any of groups R n is an integer from 1 to 3; and biologically compatible salts thereof.