A nuclease from mung bean sprouts.

For some years now a systematic survey of deoxyribonucleases has been carried out in this laboratory in the hope that a deoxyribonuclease would be found with limited, yet well defined, specificity. A preliminary note of Masui, Hara, and Hiiamatsu (2) described an apparently labile DNase from soy bean sprouts which liberated first deoxyadenylic, then deoxyguanylic, acids. We encountered difficulty in locating a commercial source of sprouted soy beans, but found that mung bean sprouts are produced in large amounts as food.’ An exploratory experiment with a crude extract of mung bean sprouts showed that deoxyadenylic acid was the only mononucleotide formed from DNA. Deoxyadenosine, however, was also present. It was decided, therefore, to purify this DNase and to study its specificity. In the course of this work it was found that the enzyme hydrolyzed DNA and RNA at approximately the same rate, and that, it formed similar types of products from both. This made it rather unlikely that the DNase was persistently contaminated with an RNase of identical specificity. The purified mung bean sprout enzyme is therefore called a nuclease rather than a deoxyribonuclease.