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 C [double bond, length as m-dash] O. 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.

Diamide 40 chloride transporter.

References:

Santacroce, P.V., J.T. Davis, M.E. Light, P.A. Gale, J.C. Iglesias-Sanchez, P. Prados, and R. Quesada. (2007). Conformational control of transmembrane Cl^- transport. J. Am. Chem. Soc. 129: 1886-1887.