Ascorbate peroxidase (APOX) activity, which catalyzes the oxidation of ascorbic acid with the concurrent reduction of hydrogen peroxide (H2O2), was found in larvae of Helicoverpa zea. Since insects apparently lack a Se-dependent glutathione peroxidase and since catalase has a low affinity for H2O2, this enzyme may be important in removing H2O2 in insects. We partially purified the APOX activity 58x from the whole body homogenates and investigated its activity with model lipid peroxides, electron donors, and known inhibitors of plant APOX. The H. zea APOX has activity with model lipid peroxides. This, along with the APOX activity found in fat body tissues, suggests that ascorbate peroxidase may be important in removing lipid peroxides in insects. The H. zea APOX has broader specificity for electron donors than the plant APOX with activity using cysteine, NADPH, glutathione, and cytochrome C as electron donors (22-93% of activity with ascorbate). The H. zea APOX is also resistant to many of the known inhibitors of plant APOX, suggesting that the enzyme has a different active site and may not be a heme-peroxidase.
|Original language||English (US)|
|Number of pages||12|
|Journal||Archives of Insect Biochemistry and Physiology|
|State||Published - Jan 1 1997|
All Science Journal Classification (ASJC) codes
- Insect Science