1. An enzyme produced by Aeromonas hydrophila and capable of lysing Staphylococcus aureus cells was purified 180-fold by gel filtration and chromatography on columns of AG-50 W resin. 2. Physical measurements on the purified enzyme suggest that it is a small basic protein with an isoelectric point between pH9.0 and pH9.5. 3. Maximum lytic activity was obtained in 20mm-tris-glycine buffer, pH8.5, at 45 degrees , with no detectable activity in the absence of a nitrogenous base. 4. The enzyme is active in the above buffer containing 1.5m-sucrose, and is useful for the preparation of protoplasts of Staphylococcus aureus. 5. Purified cell wall peptidoglycans of two strains of Staphylococcus aureus, differing in amino acid composition, were hydrolysed by the enzyme with the liberation of glycine oligopeptides, principally diglycine and triglycine. 6. Synthetic glycine oligopeptides larger than triglycine, but not polyglycine, were hydrolysed, as were a number of leucine-containing dipeptides and tripeptides, but no proteolytic activity could be demonstrated. 7. It is concluded that the enzyme is lytic towards Staphylococcus aureus because it splits the pentaglycine cross-links of the cell-wall peptidoglycan.

Isolated and purified cell walls of Staphylococcus aureus were treated with a purified fraction of the culture supernatant fluid of a species of Aeromonas . The course of lysis of the cell walls was followed over a period of time by examination of samples under an electron microscope. The undifferentiated cell wall was rapidly digested, but the equatorial rings were more resistant. The undifferentiated cell wall became a very thin sheet before completely dissolving, leaving a series of equatorial rings of various widths. As digestion proceeded, solubilization of the entire cell wall occurred. Analogous findings were obtained with purified S. aureus mucopeptide. It is concluded that the Aeromonas lytic principle is an enzyme, and that susceptible bonds are more concentrated in the undifferentiated cell wall mucopeptide.

Human plasma protein fraction, used worldwide as a plasma expander, produces in some recipients adverse reactions resembling those following infusion of bradykinin. The presence of excessive quantities of a Hageman factor degradation product (prekallikrein activator, PKA) in the protein solution is thought to be the reason for these reactions. Like other manufacturers, CSL has experienced batch‐to‐batch variability in the PKA levels in its plasma protein product (SPPS). In this paper, data is presented showing that PKA is inactivated to a greater extent at the high extreme (60.5 C) of the pasteurization temperature range than at the low extreme (59.5 C). This difference in pasteurization temperature can lead to a two‐ or threefold difference in PKA concentration in the final product and can make the difference between the product being potentially reactive or innocuous, as well as accounting for some of the batch‐to‐batch variability observed in the past.

No abstract

No abstract