Enzymatic Characterization of Acid Phosphatase in the Logarithmic and Stationary Phase of Leishmania major Promastigotes

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.. In the present study, ACP enzyme characteristics and its activity during logarithmic and stationary phases of Leishmania major were compared.. 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.. 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).. 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..