Physical and Biological Properties of Phage φ29 Deoxyribonucleic Acid

Abstract

Deoxyribonucleic acid (DNA) molecules having a mean length of 5.8 μm were released from purified Bacillus subtilis bacteriophage φ29 with 2 m sodium perchlorate. Small 0.1 to 0.2-μm molecules were also detected in these DNA preparations. Since intact single chains annealed to form linear duplex molecules, phage φ29 DNA was found to be nonpermuted. The molecular weights of single chains of φ29 DNA were approximately half that of native DNA, as determined by analytical band sedimentation in CsCl, indicating that φ29 DNA is composed of two continuous polynucleotide chains. The molecular weight values of native and annealed φ29 DNA from sedimentation agreed with the molecular weight values obtained from electron microscopy. The infectivity of φ29 DNA was reduced to a low level by alkaline denaturation and was partially restored by annealing.