Trypanosoma (Nannomonas) congolense: properties of hexokinase and phosphofructokinase from cultured procyclic trypomastigotes and bloodstream forms

The distribution and kinetics of two key glycolytic enzymes hexokinase (HK) and phosphofructokinase (PFK) were studied in animal-infective bloodstream forms (haematozoic trypomastigotes) and uninfective procyclic forms (insect trypomastigotes) of Trypanosoma congolense. The results show that in both forms of T. congolense HK and PFK are particulate and are probably localized in a membrane-delimited organelle, the glycosome. Hexokinases of bloodstream and procyclic forms of T. congolense are kinetically similar with respect to their affinity for glucose and ATP, the apparent Km for glucose being within the range, of 91 microM to 100 microM and that for ATP, 65 microM to 91 microM. Phosphofructokinase of both forms responds to its substrate in a complex manner: a plot of initial velocity versus substrate concentration displays intermediary plateau regions.