- Know the structure of enzymes as globular proteins
- Understand the concepts of specificity and the induced fit hypothesis
- Understand that enzymes are catalysts that reduce activation energy
- Understand how temperature, pH, substrate and enzyme concentration affect the rate of enzyme activity
- Understand how the initial rate of enzyme activity can be measured and why this is important.
- Understand how the enzymes can be affected by competitive non competitive and end product inhibition
- Know that enzymes catalyse a wide range of intra cellular reactions as well as extracellular ones
- Enzymes are catalysts (they change the speed of a reaction without being used up)
- Enzymes are globular proteins produced during protein synthesis as the mRNA (transcribed from the DNA molecule) is translated.
- Enzymes have a specific shape due to their tiers of structure working together, this means enzymes only catalyse specific reactions
- pH and temperature affect the efficiency of the enzyme because it interacts with the intramolecular bonds within the protein, thus affecting the shape of the active site.
- A reaction that building up new chemicals
- A reaction that breaks substances down
- Work inside the cells
- Enzymes that are secreted from the cell in which they are made to work in a different place
Substrate + enzyme ⇌ enzyme substrate complex ⇌ (enzyme product complex) ⇌ enzyme + products
E+S ⇌ ES ⇌ EP ⇌ E + P
This is using an enzyme whereas not using an enzyme the equation is
Substrate ⇌ Product
S ⇌ P
Lock and Key Hypothesis
- It is a simple model of an enzyme’s active site being a lock and the substrate being a key. The general principle is that only one type of substrate fits in the enzyme active site
- The active site, although being a distinctive shape, is flexible. When the substrate enters the active site the shape is modified to form the active complex
- We can measure the initial rate of reaction at each time the independent variable is changed.
- You can measure the amount of product produced over the short period of time.
- Measuring the initial rate with an excess of substrate, means factors do not alter the rate
- Build-up of products
- Lack of substrate
- Change of pH
- The inhibitor is similar to the substrate and compete for the same active site
- The inhibitor joins to the enzyme in a different location which deforms the active site for the substrate
- The inhibitor permanently alters the active site by covalent bonding to one of the groups vital for catalysis to occur.
- The end product inhibits the substrate from being catalysed therefore regulating the amount of product produced