Extracellular ribonucleases from Bacillus subtilis: I. Crystallization and specificity

Abstract

1. 1. A method is described for large scale purification of two extracellular RNases obtained from Bacillus subtilis. They are here named RNase peak I and RNase peak II respectively. 2. 2. RNase peak II was crystallised in the form of needles from homogeneous preparations obtained by the use of chromatography. 3. 3. The specificity of the RNase peak I and peak II enzymes was quite different from that of bovine pancreatic RNase. They hydrolyzed the “core” remaining after treatment of the yeast RNA fraction with bovine pancreatic RNase. But they hydrolyzed only the secondary phosphate esters of the purine riboside 3′-phosphates in RNA and cyclic guanylic and adenylic acids were then isolated as intermediary products from the dialysate. The mononucleotides and end groups of the oligonucleotides produced by the enzymes were guanylic and adenylic acids. 4. 4. The effects of metallic salts, polyvinyl sulfate and anti-RNase on the activity of RNase peak I and RNase peak II and bovine pancreatic RNase are described. 5. 5. A protein, which has no RNase activity, was obtained in cyrstalline form by crystallisation of the fraction of peak I and the sedimentation coefficient of this inactive protein was about the same as that of active RNase peak II. 6. 6. A latent RNase, which was activated by 4 M urea and was almost completely inhibited by anti-RNases, was detected in the bacterial cells.