Fig 3.

PlySK1249 in vitro activity. All experiments were done in OD₆₀₀ turbidity assays using S. dysgalactiae SK1249 as the target. (A) The specific activity of PlySK1249 was 1 U/μg. One unit of activity was defined as the amount of lysin resulting in a 50% decrease in OD₆₀₀ in 15 min (closed diamonds, PlySK1249; dotted line, controls). (B) The optimum pH was between 7 and 8.5, determined after a 15-min exposure of the cells to PlySK1249 (final concentration, 3.3 U/ml). (C and D) PlySK1249 was more active against bacteria in the early than the late stage of growth. The OD₆₀₀ at which the cells were harvested before challenge with PlySK1249 (final concentration, 3.3 U/ml) are indicated.