Enzymes: Biological Catalysts

An enzyme can be regarded as a catalyst for a biochemical reaction, or more simply, a biological catalyst. Its sole purpose is to increase the rate of a reaction, or speed up the reaction via provision of an alternative reactive pathway, which entails a lower activation energy. Enzymes participate in the reaction itself, enabling the occurrence of an alternate pathways of reaction, but they do not attain permanent changes to their structure or nature, and as a result remain unchanged preceding a reaction. It is then understood, that they can amplify the rate of a reaction, but are unable to effect upon the equilibratory position. Enzymes, unlike chemical catalysts are highly specific in terms of the reactions that they catalyse. This selective

The shape change is thus "induced" by the incoming substrate. The basis for this model relies on the fact that the enzyme molecules are malleable or flexible due to the ability of single covalent bonds to rotate freely.(Chemistry for Biologists 2004) Enzymes can be categorized into six different classes, each of which catalyse specific reactions. These classes included Oxidoreductase, Transferase, Hydrolase, Lyase, Isomerase and Ligase. Oxidoreductase catalyses an oxidation- reduction reaction as implied by its name. This reaction involves oxidation which is the loss of electrons and reduction which is the gain of electrons, both of which occur simultaneously and depend upon each other. An example of an Oxidoreductase enzyme is Lactate Dehydrogenase. The class Transferase catalyses reactions which transfer functional groups such as amino groups, phosphate groups or others. An example of the Transferase class of enzyme is Alanine Deaminase. Hydrolase catalyses any hydrolysis reaction and examples are Lipase and Sucrase. Lyase efficiently enables the removal of atomic groups independent of hydrolysis and include the enzyme Oxalate Decarboxylase. Isomerase catalyses the rearrangement of atoms within a specific molecule and an example is Alanine racemase. Finally, Ligases catalyse reactions

They serve the purpose of testing whether the substances should behave as they should. It ensures that the experimental values obtained are cohesive with secondary research and theoretical knowledge, as well as helps to identify the source of error is there is any discrepancy in the experiment. For instance, if an enzyme added to a substrate is expected to turn black in colour, then reacting either the enzyme or substrate with water should yield no colour change indicating that each is functioning properly and only giving a black colour with each other. We can thus refer to the water and either substrate or enzyme as the control experiment.(University of Arizona 2010) Hydrogen Peroxide is a toxic chemical that is a by-product of various cellular reactions that occur in our body. Due to its poisonous nature, it is capable of killing cells and as a result, they body has mechanisms in place to break down hydrogen peroxide into non harmful constituents of water and oxygen. The body's cells are able to break down the hydrogen peroxide with the help of biological catalysts or enzymes. Enzymes speed up this break down into harmless entities otherwise the reaction would occur to slowly and may destroy cells in the balance. (Biology Corner