In: Biology
Briefly explain the two theories that attempt to explain how enzymes work.
Answer:- The two important theories to explain how enzymes work :-
(1) Lock and key Hypothesis
This Hypothesis was originally proposed by a German Chemist Emil Fischer.
According to this theory, the formation of enzyme - substrate complex during enzyme action is analogous to the fitting of lock and key. It is believed that the enzyme and substrate both have strictly complementary structures which during complex formation fit to each other like a specific key in a particular lock. Such structures of enzymes are now called active sites in which the complementary structures of substrate get fit in. The enzyme substrate complex dissociates only after the conversion of substrate into products and the enzyme becomes free and available for further reactions.
(2) Induced fit Hypothesis:-
This theory was proposed by D. Koshland. According to this model , the enzyme and substrate do not have strictly complementary structures but the enzyme has flexible active site structures which are changed according to substrate configuration. This model can be compared with a type of ' hand and glove' ( the glove adjusts itself in the hands of those person who wear it.)
Diagram lock and key Hypothesis.