Effect of enzymes on reactions
The function of any enzyme largely depends on the arrangement of its amino acids. The shape of an enzyme is so important such that any alteration or change in its amino acid sequence can have a huge effect on its function. An alteration to the amino acids in an enzyme does not only alter it shape but also its functionality. During a reaction, the whole enzyme does not take part but rather a small part known as the active site. The shape and appearance of the active site in any enzyme is determined by its three dimensional structure. The active site of an enzyme houses the shape of the substrate that needs to be changed during the reaction. This means that enzymes and substrates work like a lock and key. Since a specific key can only open a specific lock, this is explains why enzymes are specific in their reactions.
How enzymes catalyze reactions
As noted earlier, enzymes serve as catalysts that speed up the rate at which biochemical reactions take place. They mainly work by offering a substitute pathway for reactions. Compared to other catalysts, the pathway provided by enzymes reduces activation energy. The same with all other catalysts, enzymes participate in reactions and this is the main way through which they offer a substitute reaction pathway. However, it is worthy noting that enzymes do not undergo any permanent changes during a reaction but remain intact. There main role in a reaction is to increase the rate but not the position of the reaction equilibrium (Cornish-Bowden 47). Unlike chemicals that catalyze a number of reactions, enzymes are usually very selective and can only catalyze precise reactions. This characteristic can be attributed to the shape of molecules that make up enzymes. Majority of enzymes are made up of a protein and non protein known as the cofactor. In most cases, the proteins found in the enzymes are globular. Any change in temperature and pH disrupts the inter-molecular and intra-molecular bonds that hold the proteins together in their tertiary and secondary structures. This means that catalytic ability of an enzyme is temperature and pH sensitive.
For any molecules to react, they must come into contact with one another. In other words, they must collide with enough energy and in the correct direction. Sufficient energy is important during a reaction because it helps the molecules overcome the energy barrier to the reaction. This type of energy is known as activation energy. During a reaction, the active side of an enzyme attaches itself to one of the reacting molecules known as the substrate. A reaction catalyzed by an enzyme takes a different route compared to that catalyzed by other catalysts. The coming together of an enzyme and a substrate results in a reaction intermediate.
Enzyme substrate Enzyme-substrate complex
The best experiment that can be used to validate the claim that enzymes do in fact catalyze reactions is looking at how enzymes help human beings digest food. There are different types of foods that are consumed by human beings. Some of the most common foods consumed by people are the two types of sugars namely disaccharides and monosaccharaides. These two sugars are derived from foods like fruits which also contain fructose and glucose. All monosaccharides derived from the foods that we eat is absorbed directly and transported to different cells in the body (Cornish-Bowden 96). Unlike monosaccharides, disaccharides need to be broken down into their monosaccharide form before they can be absorbed into the body. In the absence of a catalyst, the rate at which the absorption of monosaccharide galactose and glucose take place is very slow. Since human bodies require a lot of energy to function properly, it is important that the absorption process is quickened through the use of an enzyme. The main enzyme that is produced by human bodies to quicken the absorption process is known as a lactase. The experiment would involve the following steps.
- This experiment can be represented using the following diagram.
- Fill a tube with 20 ml of a lactose solution.
- Fill another tube with 20 ml of lactose solution and 2 ml of lactase solution. Shake the tube to ensure that the two solutions mix.
- Give the experiment 5 minutes for the lactose to breakdown into galactose and glucose.
- Use a test strip to monitor the process. Originally, the strip is usually colored aqua. If it turns brown, olive or green, it is an indication that glucose is present.
- Compare the results from the two tubes.
If the color of the test strip turns brown, olive or green, this is an indication that glucose is present. This means that reaction in the tube with lactase was catalyzed resulting in the production of glucose. The reaction in the other tube was slow because there was no catalyst to quicken the reaction. The result from this experiment indicates that indeed enzymes can play a big role in catalyzing reactions.
Cornish-Bowden, Athel. Fundamentals of Enzyme Kinetics. (3rd edition), Portland Press, 2004. Print.