The membrane-bound deoxyribonuclease(DNase) has Partially teen purified from rabbit reticulocytes, and its properties have been investigated.
Evidence is presented indicating that the DNase and ribonuclease(RNase) asso-ciated with rabbit reticulocyte membrane are distinct enzyme entities. The memb-rane-bound DNase of rabbit reticulocytes is differentiated from reticulocyte membrane-bound RNase by Sephadex-G-200 chrcmatography. The enzyme shows optimal pH around 5 and is more heat-labile than the RNase, being inactivated over 600. Mg inhibits the enzyme at 10 mM and 5 mM, respectively, suggesting that the enzyme activity is not dependent on divalentcations.
The enzyme is activated by urea above 1 M, but not influenced by phydroxymer-curibenzoate.
The enzyme acts on both native and heat-denatured DNA with preference for the former.
From the studies on the chain length of the reaction product and relationship, between enzyme activity and reaction time, it is suggested that the enzyme is of an endonuclease, and belongs to DNase-II of Lindahl´s classification.
Some inhibitors of protein nature are suggested to be present in normal erythro-cytes and reticulocytes.
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