Figure 5.

Separation of duckweed peroxidase isozymes. Plants were homogenized in extraction buffer and the resulting extract was dialysed. Isozymes were eluted from a Hi Load SP-Sepharose High Performance 26/10 column using a two-stage gradient of NaCl in 50 mm malonate (pH 5.0), and assayed using 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid (ABTS). A, Isozymes of the UV-tolerant L. gibba mutant mTR and the UV-sensitive PL 3F7-11. B, Isozymes of the UV-sensitive S. punctata ecotype 203 and the UV-tolerant ecotype 760. Major differences in activity are indicated with an arrow. Each elution profile reflects an average activity, obtained by combining the biomass of five separate duckweed cultures. In three independent repeats, the ratio of activity of mTR relative to 3F7-11 was on average 1.3 for peak I (0 m NaCl), 3.2 for peak II (0.2 m NaCl), and 1.0 for peak III (0.4 m NaCl).