Enzymes as Proteins
- Enzymes are biological catalysts
- ‘Biological’ because they function in living systems
- ‘Catalysts’ because they speed up the rate of chemical reactions without being used up or changed
- Enzymes are also globular proteins
- Critical to the enzyme's function is the active site where the substrate binds
- Metabolic pathways are controlled by enzymes in a biochemical cascade of reactions
- Virtually every metabolic reaction within living organisms is catalysed by an enzyme – enzymes are therefore essential for life to exist
- Enzymes can be intracellular or extracellular referring to whether they are active inside or outside the cell respectively
- Intracellular enzymes are produced and function inside the cell
- Extracellular enzymes are secreted by cells and catalyse reactions outside cells (e.g. digestive enzymes in the gut)
Enzymes Table
| Intracellular | Extracellular | |
| Example | Catalase | Amylase |
| Function |
|
|
Examiner Tip
Don't forget that enzymes are proteins and so anything that could denature a protein, rendering it non-operational (extremes of heat, temperature, pH etc.) would also denature an enzyme.
