An enzyme exhibiting yeast-lytic activity has been isolated from the culture liquid of the bacterium Lysobacter sp. XL 1. The optimal conditions for the hydrolysis of Saccharomyces cerevisiae cells by the enzyme have been established: 0.15 M sodium acetate buffer, pH 6.0, 50 degrees C. The yeast-lytic activity of the enzyme is inhibited by EDTA, p-chloromercuribenzoate, and phenylmethylsulfonyl fluoride. According to the data of SDS-PAGE, the molecular weight of the protein is 36 kD. The enzyme hydrolyzes casein, hemoglobin, and synthetic peptide Abz-Ala-Ala-Phe-pNA, i.e. it exhibits proteolytic activity. The properties of the enzyme and its molecular weight correspond to those of a previously isolated extracellular metalloproteinase. The N-terminal amino acid sequence of the protein exhibits 67% homology with the N-terminal sequence of achromolysine of Achromobacter lyticus (EC 3.4.24.-).