Activity and Properties of Deoxyribonuclease in the Bacteria Pseudomonas aeruginosa

The present research includes a study of the activity and properties of the extracellular enzyme DNase in the cultural supernatant of the growth of P.aeruginosa and in the cellular extract .
Maximum activity of the enzyme was obtained in a reaction mixture containing 18-24 g of enzyme extract, 5 l of 0.1 M CaCl2, 100 l of substrate (0.18 mg/ml-1 DNA in 8 mM sodium borate (pH 8.4) containing 10 mM sodium chloride) and 100 l of 8 mM sodium borate buffer (pH 8.4). The reaction mixture was incubated at 37C for 30 min. The enzyme activity was 4.520.32 units/cm3 in the cultural supernatant. The Michaelis constant (Km) value was 1.6810-4 M and the enzyme hydrolyzes RNA in addition to DNA. When RNA was used as a subtrate,the activity of DNase enzyme was 82% in culture supernatant and 75% in cell extract in comparison with the activity when DNA was the substrate.
The molecular weight obtained using gel filtration was 36000 and 48000 dalton for DNase and 17000 dalton for RNase.