RESUMO

Thermal denaturation of triosephosphate isomerase from Trypanosoma cruzi was studied by circular dicrhoism and fluorescence spectroscopies. The unfolding transition was found to be highly irreversible even at the very early stages of the reaction. Kinetic studies, allowed us to identify consecutive reactions. Firstly, only the tryptophan environment is altered. Next, changes on the secondary structure and hydrophobic surface exposure measured by 1-anilino-8-naphthalenesulfonate (ANS) binding were observed. Further conformational changes imply additional modifications on the secondary and tertiary structures and release of the hydrophobic dye leading to the formation of the unfolded state that is prone to aggregate.

Assuntos

Temperatura , Triose-Fosfato Isomerase/química , Trypanosoma cruzi/enzimologia , Naftalenossulfonato de Anilina/química , Naftalenossulfonato de Anilina/metabolismo , Animais , Sítios de Ligação , Dicroísmo Circular , Cinética , Desnaturação Proteica , Dobramento de Proteína , Espectrometria de Fluorescência