Related Experiment Video
Updated: Aug 8, 2026
10:49
Measuring Rates of Herbicide Metabolism in Dicot Weeds with an Excised Leaf Assay
Published on: September 7, 2015
Indole-3-ethanol Oxidase: Kinetics, Inhibition, and Regulation by Auxins
F W Percival1, W K Purves, L E Vickery
1Department of Biological Sciences, University of California, Santa Barbara, California 93106.
Plant Physiology
|April 1, 1973
Summary
Cucumber indole-3-ethanol oxidase is a flavoprotein enzyme. Its activity is regulated by indole-3-acetaldehyde and indoleacetic acid (IAA), suggesting a role in auxin biosynthesis.
Area of Science:
- Biochemistry
- Plant Physiology
Background:
- Indole-3-ethanol oxidase (IEO) is an enzyme found in cucumber seedlings.
- Understanding its biochemical properties is crucial for elucidating plant hormone regulation.
Purpose of the Study:
- To further characterize the enzymatic properties of indole-3-ethanol oxidase.
- To investigate the enzyme's kinetic mechanism and interactions with substrates and inhibitors.
Main Methods:
- Enzyme inhibition studies using various compounds.
- Kinetic analysis to determine the reaction mechanism.
- Investigation of cooperative interactions and regulatory effects of auxins.
Main Results:
- The enzyme appears to be a flavoprotein requiring metal ions and sulfhydryl groups.
- A ping-pong Bi-Bi kinetic mechanism was identified, with indole-3-acetaldehyde as an inhibitor.
- Cooperative interactions were observed with indoleethanol, and indoleacetic acid (IAA) acted as a noncompetitive inhibitor.
Conclusions:
- Indole-3-ethanol oxidase exhibits complex regulatory interactions involving its substrate and IAA.
- These findings provide insights into the potential role of IEO in regulating indole-3-acetic acid biosynthesis in plants.
Related Concept Videos
00:46Feedback Inhibition
Biochemical reactions are occurring constantly in cells, converting starting substances to different products, usually with the help of enzymes that speed the reactions. Without enzymes, it would take far too long for most reactions to occur to be useful to the cell!
01:22Bioreactor Controls-III
Strain improvement is a foundational strategy in industrial microbiology aimed at maximizing microbial productivity, particularly because natural isolates typically yield commercially valuable products in very low concentrations. Although optimizing the culture medium and environmental conditions can improve yields, these adjustments are inherently limited by the organism’s genetic potential. As a result, the focus shifts toward genetic modifications to enhance biosynthetic capacity. The...
01:08Allosteric Regulation
Allosteric regulation of enzymes occurs when the binding of an effector molecule to a site that is different from the active site causes a change in the enzymatic activity. This alternate site is called an allosteric site, and an enzyme can contain more than one of these sites. Allosteric regulation can either be positive or negative, resulting in an increase or decrease in enzyme activity. Most enzymes that display allosteric regulation are metabolic enzymes involved in the degradation or...
01:30Enzyme Inhibition
Inhibitors are molecules that reduce enzyme activity by binding to the enzyme. In a normally functioning cell, enzymes are regulated by a variety of inhibitors. Drugs and other toxins can also inhibit enzymes. Some inhibitors bind to the enzyme’s active site, while others inhibit enzymatic activity by binding to other sites on the protein structure.
01:25Cell Signaling in Plants
Plant cells communicate to coordinate their cycle of growth, flowering and fruiting, and activities in roots, shoots, and leaves in response to the changing environmental conditions. Plant signaling is distinct from animal signaling. Plants primarily utilize enzyme-linked receptors, whereas the largest class of cell-surface receptors in animals are G-protein coupled receptors (GPCRs). Unlike animals, receptor tyrosine kinases are rare in plants. Instead, plants have a diverse class of...
02:04Regulation of Transpiration by Stomata
During photosynthesis, plants acquire the necessary carbon dioxide and release the produced oxygen back into the atmosphere. Openings in the epidermis of plant leaves is the site of this exchange of gasses. A single opening is called a stoma—derived from the Greek word for “mouth.” Stomata open and close in response to a variety of environmental cues.