---

Plant peroxidase (EC: 1.11.1.7) a heme-containing protein which is widely used in plants, microorganisms and animals. This two - substrate enzyme, catalyze the hydrogen peroxide into water with   oxidation of many organic and inorganic substrates that all of them can be used to measure enzyme activity. Although it’s specific substrate is hydrogen peroxide. Calcium and at least four disulfide bonds in the protein structure lead the formation and strength of three-dimensional structure of the molecule. Plant peroxidase has several roles including, involvement in lignin biosynthesis, auxin metabolism, cell growth, cell wall cross linking and respond to environmental stress. So peroxidase, considered as a good point to pursue the cell deal with stress factors such as oxidative stress. These days according to produce the pure samples of this molecule, peroxidase also used in ligand-protein studies in pharmaceutical research. So in this brief overview, in addition to introducing plant peroxidase we have had a brief look to measure the enzyme activity, the number of isoenzymes in a cell and the ensuing conformational changes of peroxidase.

---

The Moldavian dragonhead (Dracocephalum moldavica L., Lamiaceae) is an annual medicinal plant with beneficial nutritional sources that plays important roles in human and animal feed. Nanoparticles and cold atmospheric plasma increase biochemical compounds in plants. In this study, the effects of copper nanoparticles and cold atmospheric plasma on biochemical indices of the medicinal plant Dracocephalum moldavica were investigated. Moldavian dragonhead plants were subjected to four doses of copper nanoparticles (0, 25, 50 and 75 mgl^-1) and cold atmospheric plasma at three durations (zero, 20 and 30 s). The results showed that cold atmospheric plasma significantly increases the essential oil percentage, while it decreases the amount of flavonoid content and activity of catalase and peroxidase enzymes. Cold atmospheric plasma (20 s) showed significant positive impact on essential oil content, while different time duration (20 and 30 s) did not show a significant impact on other traits. Lower doses of copper nanoparticles (25 and 50 mgl^-1) showed positive impacts on measured traits, while 75 mgl^-1 dose negatively affected the measured traits and functioned as a heavy metal. The cold atmospheric plasma and copper nanoparticles interactions indicated that cold atmospheric plasma had an incremental effect on the improvement of measured traits and increased the effect of copper nanoparticles. In conclusion, the results showed that copper nanoparticles with 25 mgl^-1 dose along with cold atmospheric plasma with 20 s duration had significant positive effects on the improvement of biochemical indices of Dracocephalum moldavica.