Purification and characterization of deoxyribonuclease from small intestine of camel Camelus dromedarius

The chromatography of deoxyribonuclease (DNase) from small intestine of camel Camelus dromedarius by DEAE-Sepharose separated three isoforms DNase 1, DNase 2 and DNase 3. The DNase 3 was purified to homogeneity by chromatography on Sephacryl S-200. The molecular weight of DNase 3 was 30 kDa using gel filtration and SDS-PAGE. The pH optimum of DNase 3 was reported at 7.0 using Tris-HCl buffer. The temperature optimum of DNase 3 was found to be 50 °C. The enzyme was stable up to 50 °C for one h incubation. The Km value was 28.5 µg DNA, where this low value indicated the high affinity of enzyme toward DNA as substrate. No activity of DNase 3 was determined in the absence of metal cations. Mg(2+) and Ca(2+) caused significant enhancement in the enzyme activity by 90 and 75%, respectively. The mixture of Mg(2+) and Ca(2+) caused 100% of enzyme activity. Ni(2+), Co(2+), Ba(2+), Zn(2+) and Cd(2+) showed very strong inhibitory effect on enzyme activity. In conclusion, the characterization of DNase 3 indicated that the enzyme is considered as a member of DNase I family. The low Km value of the DNA suggested that the high digestion of DNA of camel forage by small intestine DNase 3.