Purification and characterization of deoxyribonuclease from small intestine of camel Camelus dromedarius
Abdel-Gany, Somia S. | El-Badry, Mohamed O. | Fahmy, Afaf S. | Mohamed, Saleh A.
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 30kDa 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 28.5µg 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. Mg²⁺ and Ca²⁺ caused significant enhancement in the enzyme activity by 90 and 75%, respectively. The mixture of Mg²⁺ and Ca²⁺ caused 100% of enzyme activity. Ni²⁺, Co²⁺, Ba²⁺, Zn²⁺ and Cd²⁺ 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.
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