ニジマス幽門垂のフォスフォジエステラーゼの精製と性質

概要

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The phosphodiesterase in the pyloric caeca of rainbow trout was purified about 260-fold to investigate the role of the enzyme in the digestive organ.The optimum pH for the enzyme activity was approximately 9.0. This enzyme was activated by Mg2+ and Ca2+ and hydrolyzed RNA forming 5-mononucleotides. However, the RNA hydrolyzing activity of the enzyme was much lower than that of alkaline RNase in the same tissue. In this enzyme preparation, 2:3 cyclic nucleotide 2-phosphohydrolase activity was observed and the heat denaturation curve of this activity corresponded with that of the phosphodiesterase activity. From this fact, it is probable that this purified enzyme has both phosphodiesterase and 2:3; cyclic nucleotide 2-phosphohydrolase activity. The role of this enzyme in the digestive organ may be the cleavage of 2:3 cyclic nucleotides, which are the products of the RNA digestion by alkaline RNase, forming 3-nucleotides.