植物種子発芽体の核酸分解酵素に関する研究 : (第3報)緑豆発芽体核酸分解酵素の精製とその性質

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Nucleases from mung bean sprouts were purified by the following methods : preheating, fractionation with ammonium sulfate, absorption on calcium phosphate gel, Sephadex treatment, ethanol fractionation and column chromatography on DEAE-cellulose. Crude enzymes were separated into three fractions of nuclease and two fractions of phosphatase. And they were purified so as to increase the absorbency of nuclease by 2,000 times and that of phosphatase by 1,000times per 280 mμ, which were identical with nearly unitary protein by the starch zone electrophoresis.1) The optimum pH of the three nucleases was 4.5 (PD_1), 5.0 (PD_2) and 8.0 (PD_3) respectively, and the optimum temeperature was 60 ℃. They were considerably heat-stable and also they were stable with pH between 5.0 and 7.5.2) As being activatd by Mg^<++>, Ca^<++>, Co^<++>, Mn^<++> and Zn^<++> and inhibited by a few chelate compounds and reducing agents, they are concluded to be metal ion requiring enzymes.3) Each of PD_1,PD_2 and PD_3 showed the activity on bis (p-nitrophenyl) phosphate.The activity of PD_1 was stronger than those of PD_2 and PD_3 on RNA, DNA and thymidine-5' -p-nitrophenyl phosphate, but the former was weaker than the latter activities on RNAcore. In PD_1 hydrolysate of RNA, more 5'-pryimidine mononucleotides were found than 5'-purine monoucleotides, while in PD_2 and PD_3 hydrolysate nearly an equal molecule of 5'-mononucleotides was found. From these results, it may be concluded that PD_1 is an endonuclease with a slight specificity in its pyrimidine base and that PD_2,_3 are the exonucleases without any specificity in their bases.4) By the preheating of each of PD_1,PD_2 and PD_3 with 10^<-3> M of Zn^<++> and F^- at pH 5.5,60 ℃ for 15 min, their enzymatic activities, thermostability and pH stability were enhanced, and the optimum pH and the optimum temperature shifted.
社団法人日本生物工学会の論文
1969-01-25

植物種子発芽体の核酸分解酵素に関する研究 : (第3報)緑豆発芽体核酸分解酵素の精製とその性質

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