What is an enzyme?

Enzymes are biological molecules (mainly proteins), which act as biological catalysts, meaning that they speed up chemical reactions, without being consumed in the process.

What do enzymes do?

Enzymes provide an alternative pathway for the reaction to take place, one that requires a lower activation energy. Activation energy may be simply defined as the amount of kinetic energy needed by molecules for successful collisions to occur for reactions to take place.

By having a lower activation energy requirement, reactions can take place at a more rapid rate, hence speeding up body processes that would take too long to occur, due to the requirement of a higher activation energy, if enzymes were not present.

What is catalysis?

Derived from the word catalyst, catalysis refers to the act of a catalyst providing the alternative reaction pathway of lower activation energy, and allowing for a reaction to be sped up, without any change in the catalyst itself.

What is the importance of enzymes?

Enzymes are important at speeding up the body’s natural processes, some of which would take too long to occur otherwise, and hence increase the needed efficiency of these processes.

What are some properties of enzymes?

1.    Specific- each enzyme works on a specific substrate (the molecule acted on), following the lock and key model.

2.    Sensitive- enzymes work best at a certain pH and temperature. Low temperatures will slow down enzyme activity, while high temperatures lead to the denaturation of enzymes (the loss of enzyme shape and function).

3.    Reusable- enzymes are not consumed in the reaction, meaning that they can be used over and over.

4.    Affected by substrate concentration- enzymes activity can increase up to the point where all active sites are occupied. After this, enzyme activity levels off as all active sites become occupied.

What is the Mode of Action of an Enzyme?

The mode of action of an enzyme refers to the specific way it interacts with a substrate to catalyse a chemical reaction. This can be explained in four steps:

1.    Substrate Binding- in accordance with the lock and key model, the enzyme binds to the active site of the enzyme.

2.    Catalysis- the enzyme catalyses the reaction, forming product, without the enzyme itself being used up in the process.

3.    Product Release- the enzyme releases the products of the reaction.

4.    Repetition- as the enzyme is not used up, the reaction can occur repeatedly.

The Lock and Key Model

·       At the CSEC level, enzymes are thought to follow the lock and key model:

·       The enzyme’s active site is considered the “lock” in the model, as it has a specific shape that fits the substrate, which is considered the “key’ of the model.

·       Upon the binding of the substrate to the active site, an enzyme-substrate complex is formed, and this allows the formation of product.

·       After this occurs, the products are released, and the enzyme itself remains unchanged.

The Effect of Temperature on Enzymes

As previously mentioned, enzymes are temperature specific.

They work best at a temperature called the optimal temperature.

Temperatures lower than this will have slow product formation, as both the enzyme and substrate have lower kinetic energy, and thus would have less successful collisions where enzyme and substrate bind.

Temperatures significantly higher than this will result in the denaturation of the enzyme (altering of its 3D structure), making it unable to bind to form product.

https://imgur.com/a/lxvWOQT

The Effect of pH on Enzymes.

As previously mentioned, enzymes are pH specific.

They work best at a pH known as the optimal pH.

At a pH significantly higher than this, denaturation of the enzyme (altering of its 3D structure), making it unable to bind to form product.

https://imgur.com/a/53Rs7s7