Studies on the proteoclast (Muller's phenomenon).

Abstract

1. When coagulase-positive staphylococci are grown on nutrient agar containing fresh mammalian serum and haemoglobin, discrete areas of clearing appear in the medium near to the growth.2. These ‘plaques’ are due to proteolysis, the haemoglobin acting as a chromoprotein indicator substrate. For convenience the effect is referred to as ‘proteoclast’.3. The effect is due to the interaction of a diffusible product of the staphylococci with constituents of normal sera. The staphylococcal factor has been obtained in a bacterium-free filtrate and its interaction with serum studied quantitatively. It resists boiling.4. The number of plaques produced under defined conditions showed a linear correlation with the amount of serum used, but not with the amount of filtrate.5. By means of serial filtration through Gradocol membranes it was shown that one factor in normal serum required for the proteoclast effect is particulate, having a size of the order 20–70 m μ diameter.6. It was found that a third factor present in fresh sera was also required.7. Serum was rendered inactive by conditions of heating and ultra-violet irradiation similar to those required to sterilize vegetative bacteria and viruses.8. It is suggested that the proteoclast effect is due either to a non-pathogenic virus, or to a hitherto unrecognized particulate enzyme precursor present in sera and activated by the staphylococcal factor.