enzymatic characterization of acid phosphatase in the logarithmic and stationary phase of leishmania major promastigotes

Background: leishmania is a protozoa of trypanosomatidae family that leads to a group of disease called leishmaniasis. the pathogenesis of parasite changes during promastigotes growth and proliferation. proliferation of promastigotes includes two stages: logarithmic, and stationary. the parasite is noninfective at logarithmic stage while is infective during the stationary stage. acid phosphatase (acp) is one of the factors that supposed to play a role in preservation and survival of the parasites inside the vertebrate host body cells. objectives: in the present study, acp enzyme characteristics and its activity during logarithmic and stationary phases of leishmania major were compared. materials and methods: the growth curve of l. major (mrho/ir/75/er) was plotted by daily counting cultivated parasites and promastigotes of each stage were collected separately. frozen promastigotes of each stage were homogenized with sodium acetate and triton-x-100 and acp was measured by calorimetric assay. results: parasites at logarithmic and stationary phase were collected respectively in the fourth and seventh days. the rate of acp activity was determined to be 1.18 ± 0.01 in stationary and 0.9 ± 0.03 μm/min/mg protein in logarithmic phases. moreover, maximum speed of phosphatase enzyme (vmax) was 98.04 ± 0.96 in stationary phases and 75.76 ± 0.57 in logarithmic. in addition, michaelis-menten constant (km) in logarithmic and stationary phase was determined at 142.93 ± 4.08 and 106.39 ± 1.14 μm, respectively (p < 0.05). conclusions: in logarithmic phase, km of acp was 28% higher and the rate of acp activity and vmax were 23% lower than that of stationary phase. changes in the specifications of acp might be one of the important factors for parasites to attack the macrophages and these variations.