Dansyl-GCVLS

Description :
Fluorogenic substrate for farnesyl diphosphate farnesyltransferase (FTase). The pentapeptide is based on the C-terminal region of H-Ras with a dansyl group attached to the N-terminus. Due to farnesylation of the cysteine thiol group the dansyl group is placed from a polar to a non-polar molecular environment which is accompanied by an enhancement of fluorescence and a shift to a lower wavelength emission maximum of the dansyl group. Complete conversion of the product results in a decrease of the emission maximum wavelength from 565 nm to 515 nm together with a 13-fold enhancement in fluorescence intensity at 505 nm. Dansyl-GCVLS can be used for continuously monitoring FTase activity in the presence of farnesyl diphosphate (FPP) at 505 nm using an excitation wavelength of 340 nm (kcat = 0.5 s⁻¹; Km = 1.4 µM). It represents a useful tool for screening potential FTase inhibitors. The substrate is highly specific to FTase and is not recognized by geranylgeranyl transferse type I (GGTase I). Concentrations of stock solutions of Dns-GCVLS can be calculated from the extinction coefficient of the dansyl moiety (ε₃₄₀ = 4250 M⁻¹cm⁻¹ in 20 mM Tris-HCl, pH 7.5, 10 mM EDTA).