Give an Account of How Enzymes Work with Particular Reference to Factors That Affect Their Activities.
Question Give an account of how enzymes work with particular reference to factors that affect their activities. Answer All living things require catalysts to catalyse the reaction which they carry out to survive. Enzymes are the catalysts of biological systems without enzymes reactions in cells would occur all much to slow a rate and the organism would not survive. Most enzymes, with the exception of some RNA catalysts, are proteins. They often require a co factor such as zinc or iron, or a complete organic molecule called a co enzyme in order to work. Sometimes they require both. The complete active complex of the enzyme is called the haloenzyme, the protein part is called an apoenzyme. Enzymes work by providing an alternative environment in which a reaction can occur more quickly. A particular part of the enzyme, called the active site is where the actual catalysis occurs. It is lined by acid residues whose side chains contain functional groups which help in catalysing the reaction. The substance which binds to the active site and undergoes the reaction is called the substrate. Sometimes the active site folds completely around the substrate, sequestering it from solution and providing it with a completely different environment in which it can undergo reaction much more quickly. The complex formed by the substitute and enzyme active site, the enzyme substrate complex (first proposed in 1880 by C.A. Wortz) is essential to enzyme activity. The modern theory of enzyme action was proposed in 1930 by Haldane and collaborated on by Pauling. In this induced fit theory the substrate and enzyme active site do not initially have complementarity to each other. However the substrate is then bent to fit the shape of the active site. Thus the enzymes active site is complementary to the reaction transition state. This optimises enzyme substrate interactions during the actual stage when the substrate is undergoing reaction rather than prior to this when it