[Release of DNA from Sd phage in a protein complex]

The properties of DNA released from Cd phage upon destruction of virions by heating in solutions of low strength were studied. The viscosity of DNA released from the phage after heating in 0.01 X SSC (SSC-0.15 M NaCl divided by 0.015 M sodium citrate, pH 7.0) was found to be no more than 40% of that of DNA released from the phage destroyed by heating in 1 X SSC. Addition of salts up to 1 X SSC to the phage destroyed by heatings in 0.01 X SSC resulted in a marked increase of the viscosity of the latter. According to the results of centrifugation in cesium sulphate and sucrose density gradients, upon phage destruction by heating in 0.01 X SSC DNA war released from virions in the form of a complex with protein. Addition of NaCl up to 1 X SSC to the phage preparations destroyed in the low ionic strength solution led to destruction of this complex. The complex under study was not formed in dialysis against 0.01 X SSC of phage preparations destroyed in 1 X SSC.