THE DETERMINATION OF LYSOZYME

Abstract

A rapid and accurate method of assay for lysozyme found in natural materials is described. The method is based on the increase in light transmission of a suspension of Micrococcus lvsodeikticus after exposure to various concns. of lysozyme. A highly purified crystalline prepn. is used as a standard and evidence of lytic activity is projected on the standard curve. The concn. of lysozyme in the unknown can then be calculated. M. lvsodeikticus was grown in large quantities and treated with u.-v. light followed by lyophilization. This provided a large quantity of cells that could be stored in the ice box for use in subsequent assays. Treatment of the cells in this manner resulted in stable cell preparations with constant sensitivity. The assay method was used to determine lysozyme content in a bentonite pyridine extract of fresh hens'' egg albumin, dried egg albumin, and rat kidney extracts. Consistent values were always obtained. Hens'' egg albumin extract contained 0.86 mg. of lysozyme per ml., dried albumin showe-19.7 mg./g., and rat kidney extract assayed 0.024 mg./ml. In the case of the kidney extract the error was less than 7% which indicated the reliability of the test in testing both small and large quantities of lysozyme.