Triisopropylsilane

The solvents acetone, acetonitrile (ACN), and LC-MS/MS water were purchased from LGC Standards (Wesel, Germany) in Optigrade quality. Ethanol (absolute, p.A.), 2-propanol, hydrochloric acid (HCl), and formic acid (p.A.) were obtained from Merck (Darmstadt, Germany). Tris(hydroxymethyl)-aminomethane (TRIS; ≥99.3%) was purchased from Carl Roth (Karlsruhe, Germany), trypsin (sequencing grade) from Promega (Madison, WI, USA), and dimethyl sulfoxide (p.A.) from J.T. Baker (Center Valley, PA, USA). formic acid (for LC-MS) was bought from Honeywell (Charlotte, NC, USA). The 9-fluorenylmethoxycarbonyl (Fmoc)-l-amino acids, the amino acid-wang-resins (Fmoc-l-Arg (Pbf)-Wang Resin, Fmoc-l-Lys (Boc)-Wang Resin), dimethylformamide, trifluoroacetic acid (Peptide grade), triisopropylsilane, diisopropylcarbodiimide, and piperidine for the peptide synthesis were obtained from Iris Biotech GmbH (Marktredwitz, Germany). 6-chloro-1-hydroxybenzotriazole (6-Cl-HOBt) was purchased from Luxembourg BioTechnologies (Ness Ziona, Israel), and methanol (for LC-MS) from Merck (Darmstadt, Germany). Iodoacetamide (IAA) and DL-Dithiothreitol (DTT; ≥98%) were bought from Sigma (St. Louis, MO, USA).

Amino acids protected by 9-fluorenylmethyloxy carbonyl (Fmoc) where purchased from NovaBiochem, Watford, UK. Tenta Gel S NH₂ resin and Rink amide linker were purchased from Iris Biotech, Marktredwitz, Germany. Dimethylformamide (DMF), dichloromethane, diethyl ether, and methanol were of analytical grade (≥99.5%) and obtained from Fisher Scientific, Loughborough, UK. Triisopropylsilane (TIPS, ≥98.0% GC), phenol (≥99%), trifluoroacetic acid (TFA, ≥99%), and N,N-diisopropylethylamine (DIPEA, ≥99%) were obtained from Iris Biotech GmbH. 2-(1H-benzotriazole-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate (HBTU, ≥97%) was purchased from NovaBiochem, UK. Tri-tert-butyl 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate (DOTA-tri-t-Bu-ester) was purchased from Sigma Aldrich, Dorset, UK. All other reagents were of analytical grade.