By modern computational methods, such as the water-to-bilayer transfer free energy and hydrophobic moment values calculations, was shown that some bacillar ribonucleases with antitumor action, namely barnase and binase, have a hydrophobic segment located in helix II. Interestingly, physicochemical properties of the hydrophobic segment of above-mentioned ribonucleases different significantly. The aim of this study is to explain the evolutionary significance of bacillar secretory ribonucleases using the methods of structural bioinformatics. Although attention has long been known to antitumor action of binase, a detailed study of its natural destination in the structure biology aspect had been not observed. Secretory ribonucleases involved in the metabolism of inorganic phosphate, however, the data about the hydrophobic segment suggest that ribonucleases can play subtle biological role. Remarkably, the biosyntesis of binase, not barnase, can be stimulated by addition of dactinomycin.