Mode of Action of Enzymes Enzymes Enzymes (Gk. en = in; zym | ❗STUDY HUB ❗( NEET / JEE )M
Mode of Action of Enzymes
Enzymes
Enzymes (Gk. en = in; zyme = yeast) are proteinaceous substances which are capable of catalysing chemical reactions of biological origins without themselves undergoing any change.
Enzymes are biocatalysts.
An enzyme may be defined as "a protein that enhances the rate of biochemical reactions but does not affect the nature of final product."
Maximum enzymes (70%) in the cell are found in mitochondrion. The study of the composition and function of the enzyme is known as enzymology.
There are two views regarding the mode of enzyme action :
(1) Lock and key hypothesis
(2) Induced fit hypothesis
(1) Lock and key hypothesis : The hypothesis was put forward by Emil Fisher (1894) . According to this hypothesis the enzyme and its substrate have a complementary shape. The specific substrate molecules are bound to a specific site of the enzyme molecule.
(2) Induced fit hypothesis : This hypothesis was proposed by Daniel, E. Koshland (1959).
According to this view, the active sites of an enzyme are not rigid. When the substrate binds to enzyme, it may induce a change in shape of the enzyme molecule in such a way that it is fit for the substrate-enzyme interaction. The change in shape of the enzyme molecules can put strain on the substrate. This stress may help bonds to break, thus promoting the reaction.
