Laboratory Enzyme Inhibition Flashcards
What is the reaction between catechol and dioxygen catalyzed by catechol oxidase?
Catechol oxidase, a copper enzyme, oxidizes catechol to 1,2-benzoquinone and water.
How was UV-Vis spectroscopy used to monitor the reaction?
It measured the decrease in catechol (substrate) absorbance over time, indicating its consumption and product formation.
How do plants protect themselves from radicals formed during reaction?
Plants have antioxidant defenses like catalase and superoxide dismutase to neutralize harmful radicals.
Does the reaction involve homolytic cleavage?
No, only electron transfer from Cu(I) to O2 occurs initially.
What is monitored by UV-Vis in this experiment?
The formation of the quinone product (increasing absorbance).
What type of inhibition does p-hydroxybenzoic acid exert?
Predicted competitive inhibition due to structural similarity with the substrate.
What are potential sources of error?
Temperature, impurities, and enzyme denaturation.
Why is PPO significant?
PPO causes browning in fruits, leading to economic losses. It also plays a role in various biological processes in plants.
Discuss the mechanism involved in the experiment.
Catechol along with dioxygen in the presence of Cu2+ is oxidized to ortho-quinone.
1. A nucleophile attacks one of the hydroxyl groups of catechol, producing a negative charge on the oxygen atom of that hydroxyl group.
2. By delocalization, the eventual formation of 1,2-benzoquinone will first undergo reactions which include creating an intermediate on the other hydroxyl group.
