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Overview of Enzymes and Cellular Processes

General Function of Enzymes
- Enzymes are proteins built by cells.
- Each enzyme performs a specific chemical reaction.
- Enzymes are critical for various cellular functions, including the construction of body structures and ATP (adenosine triphosphate) recharge.
- Cellular activities depend on genetic abilities found in DNA, which dictate enzyme production.

Construction of Enzymes
- Enzymes are composed of amino acids, which are the building blocks (monomers) of proteins.
- Each enzyme can contain thousands of amino acids.
- The active site is the specific region where substrates bind to an enzyme, facilitating a chemical reaction.
Mechanism of Action
- Example animation depicts how enzymes function.
- Enzymes catalyze chemical reactions by allowing substrates to bind at the active site, analogous to a lock and key.
- When a substrate binds to the enzyme, it allows for a chemical reaction, such as hydrolysis where the substrate is split into two monomer building blocks.
Types of Reactions Enzymes Facilitate
- Hydrolysis
- Dehydration synthesis
- Enzymes turn substrates into products while the enzyme itself remains unchanged, allowing it to catalyze the same reaction repeatedly.

Pathway Composition
- Enzymes can stack into pathways, facilitating the transformation of substances step-by-step.
- Each arrow in a pathway represents a different enzyme catalyzing a specific reaction.
- Initial substrate binds to the active site of the first enzyme, yielding a product that serves as a substrate for the next enzyme.
Diversity of Enzymes in Cells
- All cells contain the same DNA, yet different types of cells (e.g., brain cells, fingernail cells, stomach cells) produce distinct enzymes to fulfill specific functions.
- Consequently, pathways vary between cells allowing them to produce various products based on their role.

Controlling Enzyme Pathways
- Cells can turn enzyme pathways on or off to regulate product concentrations.
- Methods for enzyme regulation include inhibition and environmental adjustments.
Types of Enzyme Inhibition
- Competitive Inhibition
- An inhibitor binds directly to the active site, competing with the substrate.
- Example: Statins are competitive inhibitors used to lower blood cholesterol.
- Noncompetitive Inhibition
- An inhibitor attaches to a site other than the active site, altering the enzyme structure and inhibiting its function.
- Example: Cyanide, which prevents ATP production by inhibiting energy-production enzymes.
Enzyme Binding Affinity
- High binding affinity means a strong, potentially irreversible bond between the enzyme and inhibitor.

Environmental Conditions Affecting Enzymes
- Enzymes require specific environmental conditions to function optimally, including temperature, pH, and ionic strength.
Denaturation
- The process by which enzymes lose their three-dimensional structure when exposed to unfavorable conditions, leading to loss of function.
- Once denatured, enzymes cannot return to their original configuration.
- Example: Cooking processes denature microorganisms' enzymes to prevent infection in food.

Targeting Enzymes for Treatment
- Pharmaceuticals often target specific enzymes to inhibit pathways associated with diseases.
- The development of drugs such as Paxlovid, which inhibits viral protease enzymes preventing viral replication in infected cells.
Viral Protease Inhibition
- Proteases hydrolyze proteins into amino acids, necessary for viral protein synthesis.
- Shutting down these enzymes hinders the production of new viruses, effectively controlling viral infections.

Understanding enzymes and their pathways is crucial for fields such as biochemistry and medicine.
Knowledge of inhibitors and regulatory mechanisms is applied in drug design and therapeutic interventions.