Triisopropylsilane tis

The above amidated peptides were synthesized via solid-phase peptide synthesis on a CEM Discover Microwave Peptide Synthesizer (Matthews, NC) using the Fmoc-protection strategy on Rink Amide-ChemMatrix resin (0.5 mmol/g). For coupling reactions, amino acids (5 eq) were activated with N,N′-diisopropylcarbodiimide (DIC, 5 eq, Oakwood Chemical)/Oxyma (5 eq, Oakwood Chemical) and heated to 90 °C for 2 min while bubbling with nitrogen gas in N,N-dimethylformamide (DMF, Oakwood Chemical). Fmoc deprotection was carried out with 20% piperidine (Sigma-Aldrich) in DMF supplemented with 0.1 M 1-hydroxybenzotriazole hydrate (HOBt, Oakwood Chemical) at 90 °C for 1 min while bubbling with nitrogen gas. The H3 Cleavage from the resin was performed with 92.5% TFA, 2.5% triisopropylsilane (TIS, Sigma-Aldrich), 2.5% 1,2-ethanedithiol (EDT, Sigma-Aldrich), and 2.5% H₂O for 2 h at 25 °C. The crude peptide was then precipitated by the addition of a 10-fold volume of cold ether and centrifuged at 4000 RCF for 10 min at 4 °C. The pellet was resuspended in Solvent A and purified via preparative RP-HPLC using a linear gradient from 0 to 30% Solvent B over 30 min. Fractions were analyzed on analytical RP-HPLC and ESI-MS and those containing pure product ( > 95%) were pooled, lyophilized, and stored at –80 °C.

N-fluorenyl-9-methoxycarbonyl (Fmoc)-protected L-amino acids, piperdine Rink-Amide resin (100-200 mesh, loading: 0.51 mmol g^-1), diisopropylethylamine (DiEA) and o-benzotriazole-N,N,N',N- tetramethyluroniumhexafluorophosphate (HBTU) were provided by GL Biochem Ltd. (Shanghai, China). HAuCl₄, Diisopropylethylamine (DIEA), dimethylformamide (DMF), trifluoroacetic acid (TFA) and piperdine were obtained by Shanghai Reagent Chemical Co. (China). Triisopropylsilane (TIS) was purchased from Sigma-Aldrich (USA). MTT, Dulbecco's modified Eagle's medium (DMEM), trypsin, fetal bovine serum (FBS), Penicillin-streptomycin were provided by GIBCO Invitrogen Corp. All other reagents were used without further purification.

N-Fluorenylmethoxycarbonyl (Fmoc)-protected amino-acids, and NovaSyn-TGR resin (loading 0.18 mM/g, 0.33 mM scale synthesis)” resin were purchased by Merck (Darmstadt, Germany); N,N-diisopropyl-ethylamine (DIEA), N,N-dimethylformamide (DMF, peptide synthesis grade), piperidine, dimethylformammide (DMF), N-hydroxybenzotriazole (HOBt), 2-(1-H-benzotriazole-1-yl)-1,1,3,3-tetramethyluronium tetrafluoroborate (TBTU), triisopropylsilane (TIS), and trifluoroacetic acid (TFA), were purchased from Sigma-Aldrich (Munich, Germany). Peptide solution was prepared dissolving lyophilized peptide in water. Ultrapure Milli-Q water (resistivity > 18 MΩ·cm⁻¹) was used for all experiments.