Ods 120t column

The compounds were purified on a semipreparative Varian ProStar chromatograph equipped with a Tosoh Bioscience ODS-120T column (21.5 × 300 mm, particle size: 10 µm) and a 210/254 nm dual-wavelength UV detector. For HPLC purification, solvents containing 0.1% TFA in water and 0.1% TFA in 80% acetonitrile/water and a flow rate 7 ml/min were used. Collected fractions (products confirmed by MS analysis) were lyophilized. The purity of products was confirmed by HPLC analysis with a Thermo Separation HPLC system with a UV detection (210 nm) equipped with a Vydac Protein RP C18 column (4.6 × 250 mm, particle size: 5 µm). Gradient elution of 0–80% B in 40 min was used (eluent A: 0.1% aqueous TFA in H₂O, eluent B: 0.1% TFA in 80% acetonitrile/water), flow rate of 1 ml/min.
Details concerning reagents used and syntheses of cyclic and linear peptides are given in Supplementary Information.

The crude products (QAS-phenylboronic acid derivatives) were analyzed using a Thermo Separation HPLC system with a UV detection (210 nm) on a Vydac Protein RP C18 column (4.6 × 250 mm, 5 μm), with a gradient elution of 0%–80% B in A (A = 0.1% TFA in water; B = 0.1% TFA in acetonitrile/H₂O, 4:1) for 40 min (flow rate 1 mL/min). The main reaction product was purified by a preparative reversed-phase HPLC on a Tosoh (Tosoh Tokyo, Japan) TSKgel with an ODS-120 T column (21.5 mm × 300 mm), using a linear gradient 10%–20% of B for 40 min (PhB-K(QAS)-NH₂) and 2%–12% of B for 40 min (PhB(QAS)-GGG-NH₂), flow rate 7.0 mL/min, UV detection at 220 nm. The fractions were collected and lyophilized. The identities of the products were confirmed by MS analysis using Bruker Apex-Qe (Bremen, Germany) Ultra 7 T FT-ICR mass spectrometer equipped with an electrospray ionization source.