ausblenden:
Schlagwörter:
G-PROTEINS; PROTECTING GROUP; SIGNAL-TRANSDUCTION; ENZYMATIC-SYNTHESIS; LIPID MODIFICATIONS; RAS LIPOPEPTIDES; CHOLINE ESTER; PEPTIDE
Chemistry; cell signaling; enzyme reactions; lipopeptides; protecting groups; proteins;
Zusammenfassung:
For the study of biological signal transduction via heterotrimeric N-myristoylated and S-palmitoylated G proteins, useful reagents may be lipidated peptides that contain the lipid groups and amino acid sequences of their parent lipoproteins. The synthesis of S-palmitoylated peptides like Myr-Gly-Cys(Pal)-Thr-Leu-Ser-Ala-OH (I), which represents the characteristic N-terminus of the alpha-subunit of human G(alpha O) protein, is complicated by the pronounced base- lability of the thioester. Lipidated G-protein peptide I and various fluorescent-labeled analogues thereof were built up efficiently by employing either the Pd-0-mediated removal of the allyl ester or the butyryl choline esterase-catalysed cleavage of the choline ester as key step. The removal of both blocking functions proceeds under very mild conditions and without undesired side reactions. In the cases studied the allyl ester proved to be superior to the enzyme-labile choline ester. The fluorescent-labeled lipopeptides were subjected to microinjection experiments in NIH-3T3 cells, which revealed that the compounds meet basic requirements for application in biology.
