QUESTION 5 (10 MARKS) (a) Briefly describe how enzymes work. What are 3 examples
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QUESTION 5 (10 MARKS) (a) Briefly describe how enzymes work. What are 3 examples of enzymes produced on an industrial scale? Include some details of their application 3 MARKS) b) What is meant by allosteric regulation of enzyme activity and what is the difference between allosteric activation and allosteric inhibition of enzyme activity? Is allosteric regulation an example of competitive or non-competitive inhibition of enzyme activity? (3 MARKS) (c) The Michaelis-Menten equation describes the velocity of an enzyme catalysed reaction KM +S Define each of the terms in the equation and illustrate the Michaelis-Menten equation in a sketch. What is the relationship between Vmax and KM? (4 MARKS)Explanation / Answer
a] Enzymes are biological catalysts that speed up the rate of reactions within the living cells. They are actually protein molecules and are vital for life, serving a wide range of functions in the body such as aiding in digestion, respiration, and other metabolic functions. However, enzymes are highly selective catalysts, meaning that each enzyme only speeds up a particular reaction. Enzymes can work to break large molecules into smaller, simpler ones or they can help bind smaller molecules to form new, more complex molecules.
The enzymes work by 4 steps -- 1] the enzyme and the substrate [ the molecules it will act upon], come close to each other.
2] the enzyme grabs on to the substrate at a special area called the ' active site '. There are two models explaining the enzyme-substrate interaction.
In the lock-and-key model, the active site of an enzyme is shaped in such a way that it fits perfectly into the active site of the substrate.
In the induced-fit model the enzyme as well as the active site of the substrate, alter their shape to fit together and connect.
3] As a result of the enzyme-substrate interaction, chemical reactions result which form new products.
4] The enzyme separates and goes on to catalyze other reactions.
Industrial enzymes are produced commercially and are used in a variety of industries to produce useful products.
Enzymes are used to produce biofuel. Biothenol is a type of biofuel which is produced from starchy plant materials with the use of enzymes that can efficiently making this conversion.
Amylase enzymes are widely used in textile industry for improving production methods and fabric finishing. Amylase works to reduce the starch size which gives them greater strength and prevent them from breaking while being woven into a fabric.
A number of industrial enzymes are used in the food industry to prepare food items and beverages eg Protease enzyme is used in baby food to pre-digest proteins. Besides this many types of enzymes reused in the bakery to improve the taste, flavor and shelf life of bakery products.
b] Allosteric enzymes are those which can change their conformation if an effecter attaches to them. This results in an apparent change in the binding affinity at a different ligand binding site.
In allosteric inhibition of an enzyme, the inhibitor binds to the enzyme at a site other than the active site. The shape of the active site is altered so that the enzyme can no longer bind to its substrate and its activity is inhibited.
Allosteric activation occurs when the binding of one ligand enhances the attraction between substrate molecules and other binding sites. An example is the binding of oxygen molecule to hemoglobin, where oxygen is both the substrate and the effector.
All non-competitive inhibition is allosteric inhibition but all allosteric inhibition is not non-competitive. This is so because certain forms of allosteric inhibition can prevent the substrate from binding to the active site.
c]
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