Key Concepts: Enzymes

Enzymes are biological catalysts that speed up chemical reactions in living organisms.
They are large proteins composed of amino acids.
Enzymes have a specific shape which is highly relevant to their function. The area where they bind with their substrate is known as the active site.
Each enzyme catalyses a specific reaction and will only bind to certain molecules, or substrates.
The enzyme and substrate bind together to form an enzyme-substrate complex in a mechanism often compared to a ‘lock and key.’
Enzymes work best at an optimum temperature, generally around 37 degrees Celsius in the human body but can vary for other organisms.
Beyond the optimum temperature, the enzyme begins to denature, losing its shape and therefore its ability to function effectively. This denaturation is usually irreversible.
Enzymes also have an optimum pH at which they function best. Deviation on either the acidic or alkaline side from this optimum pH can denature the enzyme.
Inhibitors are substances that can reduce the rate of enzyme reactions. They may change the structure of the enzyme or block the active site.
There are two types of inhibitors: competitive (which compete for the active site) and non-competitive (which bind somewhere else on the enzyme, changing its shape and preventing the substrate from binding).
Enzyme activity can be measured by the rate at which a substrate is broken down or a product is formed.
Enzymes play a critical role in digestion, breaking down complex food molecules into simpler ones that can be absorbed into the bloodstream. For example, amylase breaks down starch into sugars.
Enzymes also play a major role in respiration, photosynthesis, protein synthesis, and DNA replication, showcasing their importance in numerous biological processes.