Purification of Bacteriophage T4 Lysozyme

Abstract

The lysozyme of bacteriophage T4 was purified to apparent homogeneity from lysates of the phage grown on Escherichia coli.The enzyme is a single polypeptide chain of molecular weight 19,000, with a single NH&erminal methionine residue and a single COOH-terminal leuciue residue.The amino acid composition of the protein was determined.The phage lysozyme exhibits a much greater specific activity when assayed with E. coli as a substrate than does egg white lysozyme.The enzyme was found to have muramidase activity, as egg white lysozyme does, when cell walls of Micrococcus lysodeikticuswere used as substrate.The stability of the enzyme and the pH of optimum activity are described.Escherichia coli cells infected with T4 bacteriophage produce a lysozyme (first described in the related phage T2 (l)), the sole function of which seems to be the ultimate lysis of the host cell (2).The production of lysozyme is genetically controlled by the lysozyme gene of the phage (3).Since lysozyme mutants can be induced with a variety of mutagens and studied genetically, the T4 phage lysozyme system is useful for investigation of problems concerning the genetic code (4-7) and the relationship of genes to their product proteins.In the present study, lysozyme of wild type T4 phage has been purified and characterized with respect to activity, stability, amino acid composition, and terminal amino acids.The lysozyme of the related bacteriophage T2 has been partially purified and described (8) by others.