Enzymes

Enzymes are made from proteins and in some cases RNA

Enzymes are biological catalysts that speed up the rates of reactions by modifying specific substances called substrates

Enzymes speed up reactions through lowering a reactions activation level.

An activation level is the amount of energy needed for the reaction to begin

Enzymes have an active site

The active sites shape can vary depending on the arrangement of amino acids

They have a specific shape

They are specific to the substrate

Why are enzymes so specific?

Only substrates with exactly the right shape can bind to the enzyme and react.

The part of the enzyme to which the substrate binds is called the active site

The active site has a very specific shape and it is different for each enzyme.

Active sites

Active sites are very sensitive

Some factors that affect the active site can include:

Temperature:

The suitable temperature for enzymes to function properly is 37 degrees. This is known as the optimum.

If the temperature is higher or lower, it could affect the chemical bonds in the active site.

This could make them less suitable to bind substrates as higher temperatures could denature the enzymes

Ph levels:

Amino acids present in the active site are acidic or basic.

If there is a fluctuation of pH, it can make it difficult for the substrates to bind.

Extreme pH values can also denature enzymes

Enzyme concentration:

Increasing enzyme concentration will increase the rate of reaction. This is because more enzymes will be available to bind with substrates

However, after a certain concentration, any increase will have no effect on the rate of reaction

Substrate concentration:

Increasing substrate concentration increases the rate of reaction. This is because more substrate molecules will be colliding with enzyme molecules. Thus, more products will be formed

Like with enzyme concentrations, this effect is valid up to a certain concentration

Surface area

Pressure

Inhibition

Inhibitors reduce or stop the activity of enzymes in reactions via blocking or distorting the active site which inhibits the reaction.

There are 2 types of inhibitors:

Competitive inhibitors: These occupy the active site and prevent a substrate molecule from binding to the enzyme

Non Competitive inhibitors: These attach to parts of the enzyme(not including the active site) to distort the shape of an enzyme.

Lock and Key Model

In the same way that a key fits into a lock, so a substrate is thought to fit into an enzyme’s active site. The enzyme is the lock, and the reactant is the key

What are enzymes made of

Enzymes are protein molecules - they are made up of amino acids

These amino acids are joined together in a long chain, which is folded to produce a unique 3D structure

Why is shape important?

The shape of an enzyme is very important because it has a direct effect on how it catalyses a reaction

Why do enzymes have different shapes?

An enzyme's shape is determined by the sequence of amino acids in its structure, and the bonds which form between the atoms of those molecules.

Different types of enzymes have different shapes and functions because the order and type of amino acids in their structure are different