Xenopus laevis pancreatic DNase I: purification and immunological characterization

Deoxyribonuclease I (DNase I) was purified from Xenopus laevis pancreas to apparent electrophoretic homogeneity using a series of column chromatographies. The purified enzyme showed a molecular mass of about 36 kDa and maximum activity at pH 7.0-8.0, required divalent cations, Ca2+ and Mg2+, for its activity, and was inhibited by EDTA, EGTA and an antibody specific to the enzyme, but not by G-actin. The N-terminal amino acid sequence of the enzyme up to the 37th residue shared 38-44% homology with that of mammalian DNases I derived from bovine, ovine, porcine, rat, mouse, rabbit and human. A systematic survey of DNase I activity distribution in 20 different kinds of frog tissues showed that the pancreas and rectum produced higher amounts than other tissues. This is the first report concerning the purification and chemical and immunological characterization of frog pancreatic DNase I.