Table I.

Effect of the detergents SDS, CHAPS, and Triton X-100 on tomato plasma membrane NADPH oxidase activity1-a

TreatmentConcentrationRelative Activity
μM and %   % ± se
No detergent0100 ± 6
SDS40 (0.0012%)85 ± 5
100 (0.0029%)54 ± 4
200 (0.0058%)36 ± 4
3,467 (0.1%)0.8 ± 2
34,674 (1%)0
CHAPS1,626 (0.1%)75 ± 7
16,263 (1%)25 ± 5
32,526 (2%)21 ± 7
Triton X-10015,480 (1%)33 ± 5
  • F1-a  Membrane fractions were obtained from the upper phase of aqueous two-phase partitioning. The superoxide production (reduction of 2, 3-bis [2-methoxy-4-nitro-5-sulfophenyl 2H-tetrazolium-5-carboxanilicle [XTT]]) was quantified as described in “Materials and Methods.” The activity is expressed as percentage of control values without detergents (100% = 0.395 ± 0.027 of XTT formazan absorbance at 470 0.6 h−1 3 μg−1 plasma membrane protein). Means and seare calculated for two to three independent plasma membrane preparations.