Fig. 3.

Haemolytic activity of the K1 module. Titrations of K1 up to 3 μM were added to a 0.2% erythrocyte suspension in a total volume of 200 μL. Incubation with erythrocytes with K1 was done in PBS at 25 °C for 48 h. After incubation the microtitre plate was centrifuged then at 1000 × g for 10 min and the supernatants (100 μL) transferred into a new microtitre plate. Haemoglobin release was measured by absorbance at 405 nm in a microtitre plate reader. Results are representative of three separate experiments. Error bars indicate the means and SE. **, P < 0.01, ***, P < 0.001 compared with heat-treated (HT) K1 polypeptide. The results from a fitted curve with an R² value of 0.99 show that the half-maximum haemolysis induced by the K1 adhesin was at a concentration of 6.6 nM