Purification and properties of phage P22-induced lysozyme

Abstract

Phage P22 induces a lysozyme in Salmonella typhimurium cells toward the later stage of its multiplication. P22 lysozyme has been purified about 1000-fold starting from the lysate of C₁ (clear plaque-forming mutant of phage P22)-infected cells. The enzyme has an optimum pH between 7 and 8 and its activity is dependent on the ionic strength of the assay medium. Salts like MgCl₂, NaCl, and KCl are inhibitory to the lysozyme. Gram-negative cells act as better substrates for the lysozyme than do gram-positive cells. The enzyme has a molecular weight of about 2 × 10⁴ and rapidly looses its activity at temperatures higher than 40°. The properties of P22 lysozyme have been compared with those of λ and T4 lysozymes. All three lysozymes have more or less the same molecular weight and have similar properties although P22 and T4 lysozymes seem to be closer than P22 and λ lysozymes.