Thiamine triphosphatase from Electrophorus electric organ is anion-dependent and irreversibly inhibited by 4,4'-diisothiocyanostilbene-2,2'disulfonic acid.
Thiamine triphosphatase (TTPase) from membranes isolated from the main electric organ of E. electricus is activated about 8 fold by NO3-, I- and SCN- while SO42- is inhibitory. Activating anions shift the pH optimum of the enzyme from 5.0 to 8.0. The enzyme is irreversibly inactivated by low concentrations of 4,4'-diisothiocyano-2,2' disulfonic acid (DIDS), an inhibitor of anion transport. Anions protect from DIDS inactivation. These and other results suggest that the membrane-bound TTPase activity is tightly controlled, possibly through mechanisms involving anion transport.
Bettendorff
L
L
Laboratory of General and Comparative Biochemistry, University of Liège, Belgium.
Wins
P
P
Schoffeniels
E
E
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology*; D000818:Animals; D000838:Anions; D002462:Cell Membrane / Q000201:enzymology; D004557:Electric Organ / Q000201:enzymology*; D004593:Electrophorus; D007700:Kinetics; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D013267:Stilbenes / Q000494:pharmacology*; D013837:Thiamin-Triphosphatase / Q000037:antagonists & inhibitors / Q000378:metabolism*
D000838:Anions; D013267:Stilbenes; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D010744:Phosphoric Monoester Hydrolases; D013837:Thiamin-Triphosphatase; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid