For an enzyme to work it must:
- have physical contact with its substrate.
- have active site that fits substrate.
Measuring enzyme-catalysed reactions
To measure the progress of enzyme catalysed reactions, measure the time course (how long it takes an event to run its course). Events often measured:
- Formation of products of reaction.
- Disappearance of substrate.
Explanation for graph shapes:
- Lot of substrate at first.
- Easy for substrate to come into contact with active sites.
- All active sites filled and substrate broken down quickly.
- Amount of product increases as substrate decreases.
- More difficult for substrate to come into contact with active sites - less substrate and products may get int the way.
- Rate of substrate disappearance slows, graph tails off.
- Rate of reaction continues to slow until concentration of substrate cannot be measured.
- Graph flattens out as all substrate used so no new product produced.
Effect of temperature of enzyme action
NB: Rate always expressed per time unit.
Rise in temperature = more kinetic energy for molecules = molecules more more rapidly = collide with each other more often.
This means enzyme and substrate come together more often = rate of…