Evaluation of Isoprenoid Conformation in Solution and in the Active Site of Protein-Farnesyl Transferase Using Carbon-13 Labeling in Conjunction with Solution- and Solid-State NMR

Abstract

The enzyme protein-farnesyl transferase (FTase) catalyzes the farnesylation of the Ras protein and other key signal transduction proteins, using farnesyl diphosphate (FPP) as the prenyl source. Inhibitors of FTase are thus of great interest as potential novel anticancer agents. The design of such agents would be informed by a detailed knowledge of the solution conformation of FPP, as well as its conformation in the active site of FTase. Four bis-13C-labeled derivatives of farnesol and geranylgeraniol have been synthesized and used to prepare the corresponding FPP and GGPP derivatives. The labeled farnesyl and geranylgeranyl derivatives 2−7 were utilized in conjunction with solution 13C NMR to probe the conformation of the prenyl chain in a variety of different solvents. These studies, along with molecular dynamics simulations, demonstrate that the prenyl chain exists primarily in an extended conformation. Surprisingly, this preference for the extended conformation is solvent-insensitive; no significant ch...