Characterization of staphylococcal λ-lysin

SUMMARY: λ-Lysin was purifed from Staphylococcus aureus strains Smith 5R and PG23 (a toxic shock syndrome isolate) by a combination of heparin-agarose and hydroxylapatite chromatography. Both strains produced two haemolytic components, designated λ1, and λ2. Though each component was weakly haemolytic they acted synergistically to potentiate haemolysis on rabbit, sheep and human blood. Rabbit and sheep erythrocytes were more sensitive to lysis by λ-lysin than human erythrocytes. The molecular mass of λ1 was 32 kDa and its pI value was 9.4. λ2 had a molecular mass of 36 kDa and a pI value of 9.3. While both trypsin and papain acted synergistically with λ2 to induce increased haemolysis, no such synergism was seen with λ1,. Also, protease inhibitors acted to inhibit synergism between λ1, and λ2. These findings suggest that λ1 could be a protease.