Enzymes

Enzymes are proteins and control the rate ofbiochemical reactions. Enzymes are called organic catalysts and they affect the rate of chemical interactions but the catalyst molecule itself is not affected. Because the catalyst is not impacted, the enzyme is capable of repeating its function over and over again. A good comparison is a construction worker that builds or demolishes houses. The materials are used up in the process, and the worker is greatly speeding up the process while (hopefully) remaining unharmed.

What is the purpose of enzymes?

Enzymes allow reactions to occur much more quickly. For this reason they are called biological or organic catalysts. Life is a series of chemical reactions that involvesorganic molecules colliding and reacting with each other. The enzyme allows that collision to occur in a way that encourages the reaction. There are two kinds of bichemical reactions: Digestion (breaking down molecules) and Synthesis (building more complex molecules). Enzymes are so specific that each enzyme can only perform one single reaction. You have separate digestive enzymes in you that each only break down one nutrient. Enzymes are specific because of their molecular shape...

Why is the shape of enzymes important?

For a chemical reaction to work, collisions between the molecules must occur. The enzymes encourage these collisions. The enzymes themselves fit the molecules perfectly and allow them to combine in the most suitable position. This combination works just like a lock and key – they have to fit perfectly or you can’t open the door. Enzymes must fit the molecules or they won’t affect the reaction. If heat or other chemicals change the enzyme shape, the enzyme may be prevented from doing its job of catalyzing the reaction. An enzyme that has had its shape changed is denatured.

Changing the conditions of the environment that the enzyme is in could change the shape of the enzyme and denature it. The most important conditions that determine enzyme activity are pH and temperature. Each enzyme has an optimum (best) pH and temperature that will ensure that its shape is correct. Deviations from the optimum conditions will change the shape of the enzyme which will keep it from doing its job.