Enzyme Overview
In every single second, thousands of chemical reactions are taking place inside living cells. In most biochemical reactions, enzymes are needed to carry out the reactions. As for the breakdown of sucrose, the sucrase enzyme acts and makes the reaction easy and faster. Enzymes act as biological catalysts and increase the reaction’s efficiency and speed. Without these enzymes, the reaction would proceed very slowly, making life impossible.
Enzymes increase the efficiency of reaction by the decrease in activation energy.
By this diagram, let’s try to recognize the importance of enzymes. The chemical reaction that occurs without an enzyme needs more energy to activate the reaction. If more activation energy is required it slows the speed of the reaction. In the presence of enzymes, the same chemical reaction is completed with minimum energy because enzymes decrease the large amount of activation energy and speed up the reaction.
Enzymes are specific for each type of reaction and perform their specific functions. For example, both Amylase enzyme and Lipase enzyme help in digestion but they perform different functions. Amylase enzyme breaks down the starch molecule into sugars and Lipase enzyme breaks down the fats or oils into fatty acids and glycerol. Amylase cannot break the fats and Lipase cannot break down starch molecules.
Enzyme is a protein that is composed of hundreds of amino acids. These amino acids joined together and coiled upon themselves to form a globular structure. Every enzyme has an active site where the substrate is attached. Substrate means reactant. Reactants or substrates can be one or more than one. The condition in which substrate attaches to the enzyme is called enzyme-substrate complex. When the reaction is completed or reactants convert into products they separate from the enzyme. In all this process enzymes only act as a catalyst and do not affect the nature and properties of end products.
Some enzymes cannot increase the efficiency of reaction alone. Enzymes require a non-protein substance for their proper functioning. Such, a non-protein substance is called a co-factor. Co-factors act as a bridge between the substrate and enzyme. They sit at the active site of the enzyme and aid in recognizing, attracting substrate, and repelling products. They increase the efficiency of the enzyme. Moreover, sometimes provides chemical energy to enzymes which makes the reaction easier and faster. Vitamins and some metal ions are examples of co-factors.
If a co-factor is loosely attached to the enzyme it is known as coenzyme. If the co-factor is covalently bonded to the enzyme it is known as the prosthetic group. An enzyme without its co-factor is called an apoenzyme. An enzyme with its co-factor is called a holoenzyme.
Like, co-factors are the helper of enzymes although inhibitors deactivate the enzymes. Inhibitors are chemical substances that slow down or completely stop the activity of enzymes. There are two types of inhibitors; Irreversible inhibitors and reversible inhibitors. Reversible inhibitors are further divided into two types; competitive inhibitors and non-competitive inhibitors.
Irreversible inhibitors occupy the active site by forming covalent bonds or they may physically block the active site of an enzyme. In the presence of irreversible inhibitors, it is impossible for the substrate to attach to the active site of the enzyme. Irreversible inhibitors react with enzymes destroy their globular structure and turn it into a useless enzyme.
Reversible inhibitors form weak or non-covalent bonds with enzymes. Generally, like irreversible inhibitors reversible inhibitors do not react with enzymes. That’s why they can easily be removed in different ways. Their effect can also be neutralized completely or partly by an increase in the concentration of the substrate.
Competitive inhibitors are like substrates they attach to the active site and deactivate the catalytic sites of enzymes. Thus, substrate(s) do not attach and product(s) are not formed.
Non-competitive inhibitors attach other than the active site of an enzyme. They alter the structure of the enzyme in such a way that even if a genuine substrate binds the active site, catalysis fails to take place.
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