New light on the "old" chloride channel blocker DIDS

Area of Science:

• Biochemistry
• Molecular Biology
• Membrane Transport

Background:

• 4,4 '-Diisothiocyanatostilbene-2,2 '-disulfonic acid (DIDS) is a long-standing inhibitor of anion transporters.
• The precise mechanism and potency of DIDS and its derivatives in inhibiting specific ion channels remain areas of active research.

Purpose of the Study:

• To investigate the degradation products of DIDS in aqueous solution.
• To evaluate the inhibitory potency of DIDS multimers on bacterial and mammalian chloride channels.
• To explore the potential mechanism of action of DIDS polymers as channel blockers.

Main Methods:

• Hydrolysis of DIDS in aqueous solution.
• Characterization of DIDS degradation products (polymers).
• Inhibition assays using bacterial ClC-ec1 Cl(-)/H(+) exchanger and mammalian ClC-Ka chloride channel.

Main Results:

• DIDS hydrolyzes and multimerizes into di-, tri-, tetra-, and pentameric polythioureas.
• These DIDS polymers exhibit significantly higher potency (3-200 times) in inhibiting ClC-ec1 and ClC-Ka compared to DIDS itself.
• The tetra- and pentameric forms show potential as tethered blockers for dimeric CLC proteins.

Conclusions:

• DIDS degradation products are more potent inhibitors of anion transport than the parent compound.
• DIDS polymers represent a new class of potent inhibitors for CLC family transporters.
• The multimeric structure of DIDS derivatives may enable novel blocking mechanisms in dimeric channel proteins.