Chemical Synthesis of the Highly Hydrophobic Antiviral Membrane-Associated Protein IFITM3 and Modified Variants

Harmand, Thibault J.; Pattabiraman, Vijaya R.; Bode, Jeffrey W.

Opr-S3-ArgTAG 3 was synthesized on polystyrene resin (loading 0.32 mmol/g, scale: 1.0 g, 0.32 mmol). After Fmoc-Gly-OH followed by seven Fmoc-Arg(pbf)-OH were coupled via SPPS and Nterminal Fmoc-deprotection, 4-(hydroxymethyl)benzoic acid was manually coupled using HATU and NMM in DMF for 4 h. Fmoc-Gly-OH was attached to the resin via the symmetrical anhydride method using DIC in CH 2 Cl 2 /DMF for two times 2 h. The resin was subjected to the automated Fmoc SPPS using standard procedures as described in the General Methods. After the N-terminal deprotection of glycine 94, Fmoc-Opr-OH was manually coupled using HATU and NMM in DMF 4 h followed by washing with DMF, CH 2 Cl 2 and dried The dried resin was subjected to cleavage using (95:2.5:2.5) TFA:TIPS:H 2 O, filtered and the filtrate was evaporated under vacuum. The peptide segment was precipitated with Et 2 O; centrifugation and drying afforded the crude peptide (1.68 g). The crude peptide was placed in a vial under nitrogen atmosphere and could be kept for months at 4 °C.