Overview
This lecture explains enzymes, their structure and function, and their importance in biological reactions, especially in digestion.
Enzyme Structure and Function
- Enzymes are proteins that speed up (catalyze) chemical reactions.
- Each enzyme has an active site, a specifically shaped region where a substrate (reactant) binds.
- The binding between enzyme and substrate is highly specific, similar to a lock and key.
- Induced fit describes how the active site changes shape to fit the substrate perfectly.
- After binding, enzymes either build up or break down the substrate into products.
- Enzymes are catalysts, meaning they are not used up and can be reused.
Examples of Enzymes in Digestion
- Most enzyme names end in -ase (e.g., lactase, lipase, amylase, protease).
- Lactase breaks down lactose (a sugar found in milk) into smaller, digestible parts.
- Lactose intolerance occurs when someone produces insufficient lactase and cannot digest lactose efficiently.
- Lipase breaks down fats (lipids), amylase breaks down starch, and protease breaks down proteins.
Enzyme Helpers and Requirements
- Some enzymes need helpers called cofactors (inorganic) or coenzymes (organic molecules) to function.
- Cofactors and coenzymes help enzymes build up or break down substrates.
Enzyme Conditions and Denaturation
- Each enzyme has ideal conditions (specific pH and temperature) for proper function.
- If conditions shift out of the optimal range, enzymes become denatured (lose their shape) and can’t bind substrates or function.
Key Terms & Definitions
- Enzyme — a protein that acts as a catalyst to speed up chemical reactions.
- Active site — the region of an enzyme where the substrate binds.
- Substrate — the molecule an enzyme acts upon.
- Product — the molecule(s) formed from an enzymatic reaction.
- Catalyst — a substance that increases reaction rate without being used up.
- Cofactor — an inorganic helper molecule for enzyme function.
- Coenzyme — an organic helper molecule for enzyme function.
- Denatured — a state where an enzyme’s shape is altered, losing its function.
Action Items / Next Steps
- Review key digestive enzymes and their functions.
- Understand the importance of enzyme shape and conditions for activity.