Inactivation of infectivity of phiX174 DNA by menadione and reduced menadione.

Interaction of menadione and reduced menadione with phage phiX174 DNA was investigated. A concentration of 2-10(-4) M menadione inactivated 60% of the infectivity of phiX174 DNA to spheroplasts of Escherichia coli, while reduced menadione inactivated 97% of the infectivity of phiX174 DNA at the same concentration. Alkaline sucrose gradient centrifugation revealed 2-10(-5) M reduced menadione caused approximately 24% of phiX174 DNA to produce strand break under the condition of 80% lethanlity. DNA strand break was not observed even at 4 - 10(-4) M menadione. These results indicated that there were different mechanisms for inactivation of phiX174 DNA between menadione and reduced menadione.