Purification and characterization of giant empty proheads from packaging-defective 23ptg mutants of bacteriophage T4.

We constructed packaging-defective gene 23ptg mutants of bacteriophage T4 that produced giant proheads of varying lengths. The giant proheads constituted up to 20% of the total proheads. A purification protocol was developed to prepare large quantities of highly pure giant proheads. The purified giant proheads appeared to package both mature T4 DNA and concatemeric AD10 plasmid DNA in vitro.