Lecture 12 Enzyme Inhibition and Regulation Flashcards
What is enzyme inhibition?
a process that regulates enzyme activity through covalent or non-covalent means.
What do Michaelis-Menten kinetics describe?
rate of enzyme-catalyzed reactions based on substrate concentration.
How do allosteric regulators affect enzyme activity?
They bind to an enzyme away from the active site, causing a conformational change that affects activity.
What is a drawing idea for Michaelis-Menten kinetics?
A graph showing substrate concentration vs. reaction rate, leveling off at higher concentrations.
Why is enzyme regulation important?
It helps cells adapt to environmental changes, especially in metabolic pathways.
What are zymogens?
Inactive enzyme precursors need proteolytic cleavage to become active.
What is an example of enzyme regulation?
Trypsin regulation: Purified trypsin may have only 50% activity due to missing coenzymes, denaturation, wrong pH, or inhibitors.
What are methods of enzyme regulation? PMAPD
Phosphorylation: Adding a phosphate group.
Methylation: Adding a methyl group.
Acetylation: Adding an acetyl group.
Proteolytic Cleavage: Cutting part of the enzyme.
Denaturation: Loss of structure.
What are post-translational modifications (PTMs)?
Chemical changes are made to enzymes after translation, affecting function and stability. They can be reversible or irreversible.
What do kinases and phosphatases do?
Kinases add phosphate groups
phosphatases remove them, regulating enzyme activity.
What is irreversible inhibition?
An inhibitor permanently binds to an enzyme, often covalently, stopping enzyme activity.
What is reversible inhibition?
A temporary inhibitor that can be overcome by increasing substrate concentration.
What is and example of irreversible inhibition?
Aspirin irreversibly inhibits COX-1.
How do Lineweaver-Burk plots help understand enzyme inhibition?
The graph 1/[V] vs. 1/[S] to determine the type of inhibition.
What are the types of reversible inhibitors?
Competitive: Competes with the substrate for the active site.
Uncompetitive: Binds to the enzyme-substrate complex.
Noncompetitive: Binds elsewhere on the enzyme, not at the active site.
