Effect of Nucleic Acids on the Solubility of Cell Wall-Bound Saccharase of Sugar Beet Seedlings

Abstract

It was found that certain substances which made the bound saccharase insoluble were released together with the enzyme by treating cell wall of sugar beet seedlings with salt. Insolubilization of the enzyme was extremely reduced by pretreatment of the substance with either deoxyribonuclease or hot perchloric acid, but not affected by the substance pretreated with ribonuclease, alkali or Pronase. UV spectrum of the purified substance showed a maximal absorption at 260 nm and a minimal at 238 nm. The diphenylamine test for deoxyribose and the Fiske-Subbarow test for phosphorus were both positive. These results indicate that the substance causing insolubilization of the enzyme is DNA. Calf thymus DNA and Yeast RNA as well as the purified DNA from sugar beet seedlings were all effective in insolubilization of the enzyme. Association of the enzyme with these nucleic acids depended on the concentration of NaCl. The DNA’s from sugar beet seedlings and calf thymus insolubilized the enzyme at NaCl concentrations below 0.16 m, while yeast RNA below 0.04 m.