FIG. 9.

Pectate lyase activity of PelD and PelE on sugar beet pectin after pretreatment with pectin esterases. Sugar beet pectin (10 g · l⁻¹) in 0.1 M Tris-HCl buffer, pH 8.0, was incubated at 30°C for 12 h with PaeX (2.5 μg · ml⁻¹), PaeY (2.5 μg · ml⁻¹), PemA (2 μg · ml⁻¹), or combinations of these enzymes. After incubation, these mixtures were diluted 1:20 in 0.05 M Tris-HCl buffer (pH 8.0)-0.1 mM CaCl₂ and used as substrate for pectate lyase PelD or PelE. The initial rate of reaction was measured at 37°C by monitoring the absorbance at 230 nm during 2 min after the addition of the pectate lyase (0.4 U). The activities are expressed as percentages of the maximal values.