Purification of an Endonuclease Present in Chrysaora quinquecirrha Venom

Abstract

Abstract

A DNase was isolated from the nematocyst venom of the sea nettle (Chrysaora quinquecirrha). This enzyme was purified 880-fold by sequential affinity chromatography. The enzyme had a pH optimum of 6.8, a molecular weight of 110,000 daltons, an isoelectric point of 6.9, and was active only on single-stranded DNA. The activity of the DNase could be inhibited by bivalent ions (Ca²⁺, Mg²⁺, and Zn²⁺) but was stimulated by sodium chloride. The nettle DNase could incise superhelical DNA only in low saline concentrations. Nettle DNase lacked 3′- to 5′-exonucleolytic activity, and its endonucleolytic activity produces cleaved reaction products containing 5′-phosphoryl or 3′-hydroxyl end nucleotides.