Anonymous
Jan 4
Nomenclature and classification of enzymes and mechanism of enzyme action?
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Jan 4
Nomenclature and Classification of Enzymes:
Enzymes are classified and named based on the type of reaction they catalyze and the substrates they act upon. The International Union of Biochemistry and Molecular Biology (IUBMB) has established a system for enzyme nomenclature. Enzymes are named by adding the suffix "-ase" to the name of the substrate or the type of reaction they catalyze. For example, the enzyme that catalyzes the hydrolysis of sucrose is called sucrase.
Enzymes are classified into six main classes based on the type of reaction they catalyze:
1. Oxidoreductases: These enzymes catalyze oxidation-reduction reactions, involving the transfer of electrons between molecules.
2. Transferases: Transferases catalyze the transfer of functional groups, such as methyl, acetyl, or phosphate groups, from one molecule to another.
3. Hydrolases: Hydrolases catalyze hydrolysis reactions, where a molecule is broken down by the addition of water.
4. Lyases: Lyases catalyze the addition or removal of a group from a molecule, without hydrolysis or oxidation-reduction.
5. Isomerases: Isomerases catalyze the rearrangement of atoms within a molecule, resulting in the formation of isomers.
6. Ligases: Ligases catalyze the joining of two molecules, usually with the consumption of ATP.
Mechanism of Enzyme Action:
Enzymes function by lowering the activation energy required for a chemical reaction to occur. They do this by binding to the substrate and facilitating the formation of the transition state, which is a high-energy intermediate that leads to the formation of the product.
The mechanism of enzyme action can be described by the lock-and-key model or the induced fit model. According to the lock-and-key model, the enzyme's active site has a specific shape that perfectly matches the shape of the substrate, similar to a lock and key fitting together. In the induced fit model, the active site of the enzyme undergoes a conformational change upon substrate binding, allowing for a better fit between the enzyme and the substrate.
Once the substrate binds to the enzyme's active site, several mechanisms can occur to catalyze the reaction:
1. Acid-Base Catalysis: The enzyme donates or accepts protons, altering the pH and facilitating the reaction.
2. Covalent Catalysis: The enzyme forms a covalent bond with the substrate, stabilizing the transition state.
3. Metal Ion Catalysis: Metal ions bound to the enzyme participate in the reaction by stabilizing charges or facilitating the formation of reactive intermediates.
4. Proximity and Orientation Effects: The enzyme brings the substrates into close proximity and proper orientation, increasing the likelihood of a reaction.
5. Transition State Stabilization: The enzyme binds more tightly to the transition state than to the substrate or product, lowering the activation energy.
Overall, enzymes play a crucial role in biological processes by accelerating chemical reactions, allowing them to occur at a faster rate and under milder conditions.
Enzymes are classified and named based on the type of reaction they catalyze and the substrates they act upon. The International Union of Biochemistry and Molecular Biology (IUBMB) has established a system for enzyme nomenclature. Enzymes are named by adding the suffix "-ase" to the name of the substrate or the type of reaction they catalyze. For example, the enzyme that catalyzes the hydrolysis of sucrose is called sucrase.
Enzymes are classified into six main classes based on the type of reaction they catalyze:
1. Oxidoreductases: These enzymes catalyze oxidation-reduction reactions, involving the transfer of electrons between molecules.
2. Transferases: Transferases catalyze the transfer of functional groups, such as methyl, acetyl, or phosphate groups, from one molecule to another.
3. Hydrolases: Hydrolases catalyze hydrolysis reactions, where a molecule is broken down by the addition of water.
4. Lyases: Lyases catalyze the addition or removal of a group from a molecule, without hydrolysis or oxidation-reduction.
5. Isomerases: Isomerases catalyze the rearrangement of atoms within a molecule, resulting in the formation of isomers.
6. Ligases: Ligases catalyze the joining of two molecules, usually with the consumption of ATP.
Mechanism of Enzyme Action:
Enzymes function by lowering the activation energy required for a chemical reaction to occur. They do this by binding to the substrate and facilitating the formation of the transition state, which is a high-energy intermediate that leads to the formation of the product.
The mechanism of enzyme action can be described by the lock-and-key model or the induced fit model. According to the lock-and-key model, the enzyme's active site has a specific shape that perfectly matches the shape of the substrate, similar to a lock and key fitting together. In the induced fit model, the active site of the enzyme undergoes a conformational change upon substrate binding, allowing for a better fit between the enzyme and the substrate.
Once the substrate binds to the enzyme's active site, several mechanisms can occur to catalyze the reaction:
1. Acid-Base Catalysis: The enzyme donates or accepts protons, altering the pH and facilitating the reaction.
2. Covalent Catalysis: The enzyme forms a covalent bond with the substrate, stabilizing the transition state.
3. Metal Ion Catalysis: Metal ions bound to the enzyme participate in the reaction by stabilizing charges or facilitating the formation of reactive intermediates.
4. Proximity and Orientation Effects: The enzyme brings the substrates into close proximity and proper orientation, increasing the likelihood of a reaction.
5. Transition State Stabilization: The enzyme binds more tightly to the transition state than to the substrate or product, lowering the activation energy.
Overall, enzymes play a crucial role in biological processes by accelerating chemical reactions, allowing them to occur at a faster rate and under milder conditions.
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