2.1. Synthesis, purification and chemical characterization of BK-(1-9), BK-(1-5) and B1 receptor antagonist
BK-(1-9) [RPPGFSPFR], BK-(1-5) [RPPGF] and the B1 receptor selective antagonist Lys-(des-Arg9-Leu8)-BK-(1-9) [KRPPGFSPL] were synthesized by solid-phase peptide synthesis employing the Fmoc strategy (Chan et al. , 2000), using NovaSyn-TGA resins (Merck, Kenilworth, NJ, USA). The final unprotected peptides were purified by HPLC using a DiscoveryBIO® Wide Pore C18 semi-preparative column. Purified products were analysed by MALDI TOF/TOF Autoflex III Smartbeam mass spectrometer (Bruker Daltonics, Hamburg, Germany) for synthesis quality control.