Characterization of Trypanosoma cruzi hexokinase

Properties of hexokinase (EC 2.7.1.1) from Trypanosoma cruzi epimastigote forms (Tulahuen strain) were studied and compared with enzymes from other sources. The enzyme activity was 37 units g-1 of wet cells (1.2 units mg-1 protein). Hexokinase showed Km values for glucose and ATP of 0.09 and 0.4 mM, respectively. The enzyme reacted with other nucleotides too. N-Acetylglucosamine was a competitive inhibitor with respect to glucose (Ki = 0.3 mM). ADP inhibited the enzyme competitively with respect to ATP (Ki = 1.5 mM) and noncompetitively with respect to glucose (Ki = 7 mM). The enzyme was markedly inhibited by 5-thioglucose, its Ki value was 0.4 mM. Hexokinase activity was not affected by glucose 6-phosphate.