Enzyme

Enzymes

Enzymes are proteins. They are made of amino acids and folded into different shapes. At most of the time, enzymes function as catalysts. They increase the rate of reactions by lowering the activation energy (minimum energy required for a reaction to take place). As a result, products are formed faster and reactions reach their equilibrium state more rapidly.

Reactants that bind to enzymes are called substrates. Substrates usually attach themselves to enzymes at specific regions called active sites of the enzyme. The active sites have precise shapes for substrates. It works like a lock and a key, in which the enzyme is a lock and the substrates are the key. After the reaction, products are released from the active sites as well.

There are two types of enzyme inhibitors. The first type is called competitive inhibitors. This type of inhibitor binds to the active site and blocks the substrate from attaching to the enzyme. The second type is called non-competitive inhibitor. This type of inhibitors binds to a regulatory region and changes the shape of the active site, and thus substrates cannot bind to them.

Some enzymes have positive feedback system. When the detector senses that products are produced, the enzymes process more reactions and produce more products. The negative feedback system is more common. When the detector senses there are excessive products, enzymes lower the rate of reaction.

Enzymes also work best in specific environments, where the temperature and pH values suit them best. For example, pepsin digests polypeptides in the stomach where the environment is extremely acidic. The enzymes will change the shape of their active sites when the pH value and temperature is not the best for them.