Highly specific inactivation of triosephosphate isomerase from Trypanosoma cruzi.
We searched for molecules that selectively inactivate homodimeric triosephosphate isomerase from Trypanosoma cruzi (TcTIM), the parasite that causes Chagas' disease. We found that some benzothiazoles inactivate the enzyme. The most potent were 3-(2-benzothiazolylthio)-propanesulfonic acid, 2-(p-aminophenyl)-6-methylbenzothiazole-7-sulfonic acid, and 2-(2-4(4-aminophenyl)benzothiazole-6-methylbenzothiazole-7-sulfonic acid. Half-maximal inactivation by these compounds was attained with 33, 56, and 8 microM, respectively; in human TIM, half-maximal inactivation required 422 microM, 3.3 mM, and 1.6 mM. In TcTIM, the effect of the benzothiazoles decreased as the concentration of the enzyme was increased. TcTIM has a cysteine (Cys 15) at the dimer interface, whereas human TIM has methionine in that position. In M15C human TIM, the benzothiazole concentrations that caused half-maximal inactivation were much lower than in the wild type. The overall findings suggest that the benzothiazoles perturb the interactions between the two subunits of TcTIM through a process in which the interface cysteine is central in their deleterious action.
Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70242, D.F., Mexico, Mexico.
Alfredo
A
Téllez-Valencia
Santiago
S
Avila-Ríos
Ruy
R
Pérez-Montfort
Adela
A
Rodríguez-Romero
Marieta
M
Tuena de Gómez-Puyou
Francisco
F
López-Calahorra
Armando
A
Gómez-Puyou
D000818:Animals; D052160:Benzothiazoles; D003545:Cysteine / Q000737:chemistry / Q000378:metabolism; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D006801:Humans; D020128:Inhibitory Concentration 50; D008956:Models, Chemical; D011485:Protein Binding; D013844:Thiazoles / Q000378:metabolism / Q000494:pharmacology; D014305:Triose-Phosphate Isomerase / Q000378:metabolism*; D014349:Trypanosoma cruzi / Q000201:enzymology*
D052160:Benzothiazoles; D013844:Thiazoles; D014305:Triose-Phosphate Isomerase; C005465:benzothiazole; D003545:Cysteine