Molecular properties of streptococcal nuclease purified from Streptococcus sp. were examined. The purified enzyme was stable in the range of pH 7 to 10 and easily inactivated above $60^{circ}C$. Atomic spectroscopy analysis indicated that the enzyme contains Ca, Mg, Zn. Circular dichroism study showed 25% $alpha$ -helix, 15% $eta$-sheet and 30% $eta$-tums.