The preparation, properties and action on Staphylococcus aureus of purified fractions from the cationic proteins of rabbit polymorphonuclear leucocytes.

A micropreparative electrophoresis system for purifying the major staphylocidal fractions of cationic proteins from rabbit polymorphonuclear leucocytes is described. The most staphylocidal fraction prepared is also the most cationic and contains two bands migrating immediately behind protamine sulphate on analytical acid gel electrophoresis. SDS gel electrophoresis indicates that these proteins have low molecular weights between 3,500 and 14,400. The staphylocidal activity of the fraction is affected in the same manner as a crude extract of rabbit PMN granules by iron compounds, respiratory inhibitors, and compounds affecting energy transfer and oxidative phosphorylation. It is stable to heating up to 80 degrees and amino acid analysis shows that it contains 24% arginine. Electron microscopy of staphylococcal spheroplasts treated with the purified fraction or with the crude extract shows that they both have a very marked "blebbing" and distorting action on the double membrane. Comparisons are made between the action of the purified fraction and protamine, and it is concluded that they have very similar, although not identical, properties and actions on staphylococci.