Enzyme Lab Report

Enzyme action is the simple mechanism by which enzymes catalyse chemical reactions. This begins with the binding of the substrate to the active site on the enzyme. The binding of the substrate to the enzyme causes changes in the distribution of electrons in the chemical bonds of the substrate. This then causes the reactions that lead to the formation of products that are then released from the enzyme surface to regenerate the enzyme for another reaction cycle. The active site has a unique shape that is complementary to the shape of a substrate molecule therefore, enzymes specifically react with only one or a very few similar compounds.

Enzyme inhibitors are molecules that interact in some way with the enzyme to prevent it from working in
The inhibitor competes for the same active site as the substrate molecule. The inhibitor may connect with the enzyme at the active site, but no reaction occurs. The inhibitor binds with the active site of the molecule and prevents any substrate molecules from binding with the enzyme. A non-competitive inhibitor is a substance that reacts with the enzyme either far away from or very close to the active site. The main aim of a non-competitive inhibitor is to change the shape of the enzyme so that the substrate can no longer interact with the enzyme to give a reaction. The inhibitor molecule binds to a part of the enzyme other than the active site and then prevents the binding of substrate. There are two different theories as to how enzymes and the substrate bind, these being the Lock & Key theory and the induced fit model. The Lock & Key theory says that the shape of the key being the substrate is complimentary to the shape of the lock, which is the enzyme’s active site. When this occurs, the enzyme-substrate complex form, which then leads to the development of the products that have a different shape from the substrate, preventing reattachment to the enzyme’s active site. This theory explains why high temperatures denature enzymes and also why some substances can inhibit
This theory states that enzymes lower activation energy as when the enzyme changes shape it puts strain on the substrate, which distorts a particular bond therefore lowering the activation energy. The induced fit model says that when a substrate binds to an enzyme, the enzyme momentarily changes shape to accommodate the substrate. While the enzyme is still particular to substrates, it is not as if the substrate is a precise fit on the active site of the enzyme. After the reaction is complete, the enzyme returns back to its original shape, ready to be reused.

The Induced fit theory is a modified version of lock-and-key theory and unlike the Lock-and-key theory; the induced fit does not depend on the precise contact being made between the active site and substrate. As well as this, in the induced fit theory the enzyme shape is affected by the substrate but in the Lock-and-key theory, the enzyme affects the substrate shape. In the Lock-and-key theory, the active site has a precise shape whereas the induced fit theory doesn’t. Instead, the site shape is formed according to the substrate that is going to bind to the active