Mechanism of Enzyme Action. Lock and Key model. Induce fit Model

Enzymes are biological molecules that catalyze chemical reactions, and their mechanism of action involves several steps:
1. *Substrate binding*: The enzyme recognizes and binds to its specific substrate, fitting into the active site.
2. *Conformation change*: The enzyme undergoes a slight conformational change, positioning the substrate for catalysis.
3. *Catalysis*: The enzyme facilitates the chemical reaction, often involving acid-base or covalent interactions.
4. *Product release*: The product is released from the active site, and the enzyme returns to its original conformation.
5. *Regulation*: Enzyme activity can be regulated through various mechanisms, such as inhibition, activation, or allosteric modulation.
This precise mechanism allows enzymes to accelerate specific reactions, ensuring efficient cellular processes.
lock and key model
The lock and key model is a classic representation of enzyme-substrate binding, proposed by Emil Fischer in 1894. It suggests that:
The enzyme (lock) has a specific, complementary shape to the substrate (key).
The substrate fits perfectly into the enzyme's active site (lock), allowing catalysis to occur.
The enzyme's active site is shaped to recognize and bind specifically to its substrate, ensuring high efficiency and accuracy.
This model illustrates the high specificity of enzymes for their substrates, making enzyme-substrate interactions highly efficiency
induce fit model
The induced fit model is a refinement of the lock and key model, proposing that:
The enzyme's active site is not a perfect fit for the substrate, but rather a "good enough" fit.
When the substrate binds, the enzyme's active site undergoes a conformational change, adapting to fit the substrate more precisely.
This induced fit allows the enzyme to form a tighter complex with the substrate, positioning it for efficient catalysis.
This model acknowledges that enzymes are dynamic structures, and their active sites can adjust to optimize substrate binding and catalysis.
The induced fit model better explains:
Enzyme promiscuity (ability to bind multiple substrates)
Enzyme specificity (ability to distinguish between similar substrates)
Allosteric regulation (regulation of enzyme activity through conformational changes)