PURIFICATION, CHARACTERIZATION, AND AMINO-ACID SEQUENCING OF DNASE-GAMMA FROM RAT SPLEEN

An endonuclease named DNase gamma was purified to apparent homogeneity from rat splenocyte nuclei and its properties were characterized, We also determined the NH2-terminal and partial amino acid sequences of t he proteolytic internal peptides, The molecular mass of gamma DNase wa s 33,000 daltons as determined by SDS-polyacrylamide gel electrophores is. A native molecular mass of 30,000 was estimated by gel filtration. Purified DNase gamma is active in the presence of both Ca2+ and Mg2or Mn2+ alone and inhibited by Co2+, Ni2+, Cu2+, and especially Zn2+. Maximal activity was achieved at pH 7.2 in Mops-NaOH buffer. The seque nce data on the NH2-terminal and seven internal peptides obtained by s equential digestions with Achromobacter protease I and endoproteinase Asp-N revealed that DNase gamma is a novel endonuclease that shows seq uence homology with DNase I. (C) 1997 Academic Press.