Endo-deoxyribonuclease and process for the production thereof

Claim 1

Endo-deoxyribonuclease A (Endo-DNase A) which has the substrate specificity of recognizing specific base sequence in double-stranded deoxyribonucleic acid (DNA) molecules and cleaving the strands at specified site(s) in the DNA to produce specific DNA fragments: the DNase A being capable of recognizing the following nucleotide sequence in the molecule of pBR 322 DNA and cleaving the said DNA in one position sequence at the indicated vertical arrows, ##STR2## and cleaving φ105C phage DNA and M2 phage DNA in several positions, and λ phage DNA, φNR2 phage DNA, φ1 phage DNA, SPP1 phage DNA and ρ11 phage DNA in many positions; having the optimum pH of 6.5 to 10.0 in 50 mM Tris-HCL buffer; having the working temperature of about 30° to about 37° C.; being activated with Mg ++ or Mn ++ ; being inhibited with more than 0.2 M of NaCl or KCl, and having molecular weight of about 80,000 daltons measured by a gel filtration method using Ultro gel AcA 44, said enzyme being obtained from a cell-free extract of a DNaseA-producing microorganism belonging to the genus Saccharomyces or Pichia in a culture medium, collecting the cells thereof, obtaining cell-free extract therefrom, separating and collecting the DNase A.