Three‐step procedure for preparation of pure Bacillus altitudinis ribonuclease

Ribonucleases are considered as promising tools for anticancer treatment due to their selective cytotoxicity against tumor cells. We investigated a new RNase from Bacillus altitudinis termed BALNASE (B. altitudinis RNase). Balnase is a close homolog of the well‐known cytotoxic binase, differing by only one amino acid residue: nonpolar hydrophobic alanine at position 106 in the balnase molecule is replaced by a polar uncharged threonine in binase. The most exciting question is how the physico‐chemical properties and biological effects of RNase might be changed by A106T substitution. Here, we have developed a chromatography‐based rapid and modern technique for the purification of this new RNase which allowed us to get a protein sample of high quality with specific activity of 1.2 × 10(6) units in preparative amounts, suitable for further investigation of its biological properties.