Activity of Na+/K+-activated Mg2+-dependent ATP-hydrolase in the cell-free extracts of the sulfate-reducing bacteria Desulfovibrio piger Vib-7 and Desulfomicrobium sp. Rod-9

The aim of our work was to study Na + /K + -activated Mg 2+ -dependent ATPase activity in cell-free extracts of the sulfate-reducing bacteria Desulfovibrio piger Vib-7 and Desulfomicrobium sp. Rod-9 isolated from the human large intestine, and to carry out the kinetic analysis of the enzyme reaction. The maximum ATPase activity for both bacterial strains at +35 ºC was determined. The highest activities of the studied enzyme in the cell-free extracts of D. piger Vib-7 at pH 7.0 and Desulfomicrobium sp. Rod-9 at pH 6.5 were measured. Based on experimental data, the analysis of kinetic properties of the ATP-hydrolase reaction by the studied bacteria was carried out. The enzyme activity, initial (instantaneous) reaction rate (V 0 ) and maximum rate of the ATPase reaction (V max ) was significantly higher in D. piger Vib-7 cells than in Desulfomicrobium sp. Rod-9. Michaelis constants (K m ) of the enzyme reaction for both bacterial strains were determined.