Enzymes

Overview

Enzymes are proteins that act as biological catalysts in living organisms.
They accelerate chemical reactions without being consumed or permanently altered themselves.
Enzymes are highly specific, meaning that each enzyme is designed to catalyse specific metabolic reactions.

Enzymes have a specific region known as an active site, where the reactants, or substrates, bind.
The enzyme changes shape to fit the substrate in a process known as induced fit.
This interaction temporarily forms an enzyme-substrate complex, facilitating the reaction to take place at a faster rate.

Enzymes are sensitive to changes in their environment and their activity can be affected by a variety of factors.
Temperature: As the temperature increases, enzyme activity increases up to a point called the optimum temperature. Beyond this point, the enzyme protein denatures and its activity decreases.
pH: Each enzyme has an optimum pH at which it works best. Deviating from this optimum can reduce enzyme activity or cause denaturation.
Substrate concentration: Increasing substrate concentration increases the rate of enzyme activity. However, there is a saturation point beyond which increasing concentration does not increase activity rate.

Some molecules can negatively affect enzyme activity - these are known as inhibitors.
Competitive inhibitors bind to the enzyme’s active site, preventing the substrate from binding.
Non-competitive inhibitors bind to a different site on the enzyme, changing its shape and making it less effective or inactive.
These inhibitors can be irreversible (permanent) or reversible.

Enzymes have been harnessed for a wide variety of applications in industries and research.
They are used to enhance processes in industries like brewing, baking, detergent manufacturing and pharmaceuticals.
In medical research, enzymes are key in processes such as DNA replication and protein synthesis in the lab.

Understand the principles of Lock and Key hypothesis and Induced Fit hypothesis in explaining enzyme action.
Be familiar with the effects of temperature, pH and substrate concentration on enzyme activity.
Get acquainted with diagrams of enzyme action and learn to interpret graphs plotting rate of reaction against varying conditions.