New N-2-Labelled Fluorescent Derivatives of Guanosine Nucleotides and Their Interaction with GTP-Binding Proteins

Convenient syntheses of new fluorescent derivatives of guanosine nucleotides are described. The analogs bear a fluorescent group attached by an aliphatic linker containing 2 or 4 methylene groups on the N-2 position of the guanine base. They interact with the small GTPases H-Ras and cdc42 with an accompanying increase in fluorescence yield and display kinetic constants which are similar to those of unmodified nucleotides. The derivatives thus appear to be attractive alternatives to the widely used 2′(3′)-O-methylanthraniloyl derivatives and are likely to be useful for GTPases which do not tolerate modifications of the sugar moiety of the nucleoside.