Specific Shapes of Enzymes

Enzymes are special types of proteins that speed up chemical reactions in cells, a process known as catalysis.
Each enzyme has a unique three-dimensional shape that enables it to bind specifically with only one type of substance - the substrate.
The specific area where the enzyme binds with the substrate is known as the active site.
The shape of an enzyme and its active site is determined by its specific arrangement of amino acids. It is this shape that gives the enzyme its unique functionality.
Enzymes and their substrates work based on the ‘lock and key’ model where the enzyme (lock) only accepts a specific substrate (key).
If the shape of the enzyme changes, or denatures, it can no longer bind to its substrate. This can occur due to factors such as high temperature or changes in pH.
Enzymes are reusable and are not used up in reactions, which means one enzyme molecule can act on many substrate molecules.
Coenzymes and cofactors are non-protein chemical compounds or metallic ions that are required by an enzyme to catalyse a reaction. They can be considered ‘helpers’ that assist an enzyme in performing its function.
Inhibitors are substances that can change the shape of an enzyme’s active site and slow down or stop the enzyme from catalysing reactions. This can be either temporary (reversible inhibitors) or permanent (irreversible inhibitors).
Understanding the specific shapes of enzymes and how they work is fundamental to the study of cell biology and biochemistry.