Biochimica et Biophysica Acta, 475 (1977) 7--13 © Elsevier/North-Holland Biomedical Press
BBA 98857
ISOLATION OF A-T-RICH FRAGMENTS FROM CALF THYMUS DNA USING THE PHENOL METHOD
J. K~,YSIK, W. FIDEK and A. BRZEZII(ISKI Department of Biochemistry, Institute of Physiology and Biochemistry, Medical Academy, ~L6d~ (Poland) (Received July 8th, 1976)
Summary
The action of phenol on the products of partial digestion of calf thymus D N A by Ks DNAase causes a loss of 3--5% of the material passing into the phenol phase. This part of D N A can be regained in the aqueous phase by lowering both the temperature and the ionic strength.A m o n g oligonucleotidesup to 7 monomers in length, those which are soluble in phenol do not contain guanine residues. Phenol-soluble DNA fragments of the molecular weight of an order of 2000--50 000 appeared to be composed mainly of adenosine phosphate. They also contain some thymine and only traces of guanine and cytosine. Some longer A • T-rich fragments, even up to 5 • 106 daltons, were repeatedly found in the phenol phase, but their base composition has not been determined yet. The method presented here was found very convenient for the isolation of the relatively large A.T-rich DNA fragments. The property of DNA or its fragments to dissolve in phenol seems to be dependent on an adequate primary structure, probably similar to that of poly (dA
BBA 98857
ISOLATION OF A-T-RICH FRAGMENTS FROM CALF THYMUS DNA USING THE PHENOL METHOD
J. K~,YSIK, W. FIDEK and A. BRZEZII(ISKI Department of Biochemistry, Institute of Physiology and Biochemistry, Medical Academy, ~L6d~ (Poland) (Received July 8th, 1976)
Summary
The action of phenol on the products of partial digestion of calf thymus D N A by Ks DNAase causes a loss of 3--5% of the material passing into the phenol phase. This part of D N A can be regained in the aqueous phase by lowering both the temperature and the ionic strength.A m o n g oligonucleotidesup to 7 monomers in length, those which are soluble in phenol do not contain guanine residues. Phenol-soluble DNA fragments of the molecular weight of an order of 2000--50 000 appeared to be composed mainly of adenosine phosphate. They also contain some thymine and only traces of guanine and cytosine. Some longer A • T-rich fragments, even up to 5 • 106 daltons, were repeatedly found in the phenol phase, but their base composition has not been determined yet. The method presented here was found very convenient for the isolation of the relatively large A.T-rich DNA fragments. The property of DNA or its fragments to dissolve in phenol seems to be dependent on an adequate primary structure, probably similar to that of poly (dA
