STUDIES ON RIBONUCLEASES IN TAKADIASTASE. I

J-STAGE 1 Citations
  • SATO KIMIKO
    Laboratory of Biochemistry, Faculty of Science, University of Nagoya
  • EGAMI FUJIO
    Laboratory of Biochemistry, Faculty of Science, University of Nagoya

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Description

1. There exist two different RNases in Takadiastase as was shown by zone electrophoresis on starch column. These two enzymes are both thermostable. They were named RNase T1 (major component) and RNase T2 (minor component).<br> 2. RNase T1 has been purified 370-fold, by the following proced-ure; heat treatment, ammonium sulfate fractionation, adsorption with calcium phosphate gel and treatment with active charcoal. This enzyme was obtained in almost homogeneous state and free from RNase T2.<br> 3. The optimal pH of RNase T1 is 7.5, and it is stable near pH 6 for heating and long storage.<br> 4. The specificity of RNase T1 is different from that of RNase I. RNase T1, digesting RNA or RNase I core, produces 3'-guanylic acid much faster than other mononucleotides.<br> 5. RNase T1 is inhibited by various metal ions, e.g., Mg, Ca, Fe, Zn, Cu, etc., and activated by EDTA. Monoiodoacetate has no effect on RNase T1.<br> 6. RNase T2 has its pH optimum near pH 4.5, and is also thermostable. It is different from RNase T1 and RNase I in its specificity, e.g., it liberates adenylic acid and pyrimidine mononucleotides quickly from RNA.<br> We wish to express our thanks to Dr. R. Saruno for his kind encouragement and advice, to Prof. S. Ochoa and Dr. M. Grunberg-Manago for the gift of precious biosynthetic polynucleotides and to Prof. I. Watanabe for the gift of DNA. We acknowledge the gift of "Takadiastase Sankyo" by Sankyo Pharmaceutical Co. Ltd., too. The expense of this study was defrayed in part by a grant from the Ministry of Education.

Journal

  • J Biochem (Tokyo)

    J Biochem (Tokyo) 44 (11), 753-767, 1957

    The Japanese Biochemical Society

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