Enzymes of Nucleic Acid Metabolism from Mung Bean Sprouts
I. FRACTIONATION AND CONCENTRATION OF PHOSPHOMONOESTERASE, RIBONUCLEASES M1 AND M2, 3'-NUCLEOTIDASE, AND DEOXYRIBONUCLEASE
Tom L. Walters 1 and Hubert S. Loring 1
From the
1 From the Department of Chemistry, Stanford University, Stanford, California 94305
Several enzymes involved in nucleic acid metabolism, phosphomonoesterase, ribonuclease M1, 3'-nucleotidase, deoxyribonuclease, and ribonuclease M2, were partially purified from mung bean sprouts.
The phosphomonoesterase was separated from the other enzymes and purified 130-fold. It was shown to be nonspecific, with a pH optimum of 6.5.
RNase M1 was fractionated from the other types of enzymes by two methods, one of which resulted in a 200-fold purification. Its action on ribonucleic acid was shown to produce a mixture of 2', 3'-cyclic nucleotides; the cyclic purine nucleotides were further hydrolyzed to 3'-phosphates, while the cyclic pyrimidine nucleotides were not. The enzyme was found to be stable to dialysis at pH 5, and to have optimum activity near pH 5.5.
3'-Nucleotidase, RNase M2, and DNase, which were present in a common fraction, were purified about 50-fold. Unlike the 3'-nucleotidase and RNase M2 activities, the DNase activity declined considerably upon standing, and was therefore considered to be due to a unique enzyme. The specificities and other properties of the 3'-nucleotidase and RNase M2 are reported in two accompanying papers.
Submitted on December 8, 1965
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