2.B.108. The Diamide Chloride Transporter (D-CT) Family
A pH-dependent conformational change in diamide (40) reported by Roberto Quesada and co-workers affects Cl− transport (Santacroce et al. 2007). An increase in pH from 6.4 to 9.1 leads to decreased Cl− transport. Diamide (40) adopts a syn–syn conformation at lower pH due to intramolecular H-bonding between the phenolic-OH and the amide CO. The locked conformation enables the availability of both amide NH groups for H-bonding with the chloride ion. Deprotonation of the phenolic OH at high pH changes the conformation to syn–anti, reducing the availability of one amide NH for chloride binding.