Assays

TbTryS activity was measured at 37°C in the in vivo-like buffer. All substrate stock solutions were prepared in the in vivo-like buffer and the pH was adjusted to 7.0. The assays were performed in a final volume of 2 ml and contained 0.2 mM NADH, 1 mM phosphoenolpyruvate, 4 units pyruvate kinase, 4 units L-lactate dehydrogenase, 0.17 µM TbTryS, 2.1 mM ATP and varying amounts of glutathione, and spermidine.

This assay is designed to obtain the in vitro kinetic data of T. brucei recombinant trypanothione synthetase. The enzyme catalyzes the ATP-dependent ligation of spermidine (Spd) and GSH to generate glutathionylspermidine (Gsp) and also of Gsp and GSH to finally produce trypanothione (T(SH)2). The data was obtained in an spectrophotometric assay that links ADP production with NADH consumption through the piruvte kinase and lactate dehydrogenase.

We here create a kinetic model for a single enzyme within the T. brucei trypanothione synthesis pathway, the enzyme trypanothione synthetase based on the insights from the laboratory experiments