ACTIVITY AND KINETIC PROPERTIES OF ADENOSINE 5′-PHOSPHOSULFATE REDUCTASE IN THE INTESTINAL SULFATE-REDUCING BACTERIA

Abstract

Adenosine 5′-phosphosulfate (APS) reductase activity and the kinetic properties of the enzyme from intestinal sulfate-reducing bacteria Desulfovibrio piger Vib-7 and Desulfomicrobium sp. Rod-9 has never been well-characterized and has not been studied yet. The aim and background of this work was to investigate the dissimilatory APS reductase activity in cell-free extract of intestinal sulfate-reducing bacteria D. piger Vib-7 and Desulfomicrobium sp. Rod-9 and to carry out the kinetic analysis of enzymatic reaction. Methods. Microbiological, biochemical, and biophysical methods of the studies, and statistical processing of the results were used; the obtained data were compared with those from literature. Results. Dissimilatory APS reductase activity in the sulfate-reducing bacteria isolated from human intestine was studied. The highest activity of the enzyme (0.34±0.029 U×mg-1 protein) was measured in the cell-free extract prepared from D. piger Vib-7 cells then from Desulfomicrobium sp. Rod-9 (0.22±0.018 U×mg-1 protein). The optimal temperature (+35 oC) and pH (8.0) for APS reductase reaction were determined. The analysis of the kinetic properties of the bacterial APS reductase was carried out. The APS reductase activity, initial (instantaneous) reaction rate (V0) and maximum rate of the APS reductase reaction (Vmax) in both D. piger Vib-7 and Desulfomicrobium sp. Rod-9 bacterial strains were defined. Michaelis constants (Km) of the enzyme reaction (4.33±0.47 and 3.57±0.32 mM for D. piger Vib-7 and Desulfomicrobium sp. Rod-9, respectively) were determined. Conclusion. The described results of these studies can be the prospects to clarify the etiological role of these bacteria in the development of inflammatory bowel diseases humans and animals.