STUDIES ON THE COLIPHAGE T3

II. PREPARATION AND SOME PROPERTIES OF T3 DNA

Abstract

1. It was very difficult to extract the deoxyribonucleic acid from purified coliphage T3 by the usual phenol method. But after acid treatment, T3 DNA became easily extractable by shaking with phenol. A suspension of T3 was first acidified to pH 4.7 by the addition of 0.1M acetate buffer and stood for 10 minutes and then neutralized to pH 8 with 1M Tris pH 9.3. An equal volume of freshly distilled phenol was added and the suspension was shaken for 15 minutes and centrifuged. From the water layer of the centrifugate, DNA was recovered by the usual procedure in a good yield.
2. This preparation was free from any protein and its value of ε(P) was 6400 at 260mμ.
3. The base composition of this preparation was determined by quantitative paper chromatography. Its base ratio was G:A:C:T=25.8:24.0:24.0:26.2