Illustrate the lock and key hypothesis of enzyme action.


Lock and key hypothesis of enzyme action

Enzymes can be defined as biological polymers that catalyze biochemical reactions. Enzymes are a linear chain of amino acids that generate the three-dimensional structure. The sequence of amino acids enumerates the structure, which in turn identifies the catalytic activity of the enzyme. The structure of the enzyme denatures when heated, leading to loss of enzyme activity, which is typically connected to the temperature. Enzymes enhance the rate of reactions. Enzymes bind to a given substrate material to produce the desired product. When the enzyme binds to substrate, it forms an intermediate complex before the final product is formed. The reaction takes place in two ways as given below,

Step1: Combining of enzyme and the reactant/substrate.

E + S → [ES]

Step 2: Disintegration of the complex molecule to give the product.

[ES]→ E + P

Thus, the whole catalyst action of enzymes is summarized as:

E + S → [ES] → [EP] → E + P

Fischer has developed a Lock and Key theory to describe the mode of action of the enzyme. According to this principle, if the right key fits inside the right lock, the lock will be opened otherwise it will not. Likewise, if the right enzyme fits into the right substrate, the drug will form, otherwise, it won’t. Enzyme shape provides surface configurations that can fit with the other molecules. The molecules on which the enzymes act are known as substrates of enzymes. Substrates that have the correct geometric shape can fit within the active site of the enzyme. The active site of the enzyme is highly specific about the surface of its substrates. The enzyme and substrate fit like a lock and key, making it a lock and key enzyme action model. Sometimes, however, certain molecules close to the substrate may also interact with an enzyme’s active site. The molecule completes with the substrate and can either slow down or stop the reaction. Such substance is called the competitive inhibitor because it acts to prevent a product from being created.

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