Question

How does Active Site, Tertiary Structure, and Substrate Specificity influence an enzymes activity?

Answer 1

Enzyme:

Enzymes are proteins that are involved in various chemical reactions. Each enzyme has a specific substrate and capable of accelerating a reaction.

Tertiary structure of enzymes:

• Enzymes are made of aminoacids which are linked together by the peptide bond forming a polypeptide chain – primary structure of protein.
• Hydrogen in the amino group and oxygen in the carboxyl group further can interact with other aminoacids through hydrogen bonding forming alpha helix, beta sheet – forming the secondary structure of proteins.
• Further folding of secondary structure of proteins forms the tertiary structure of proteins.
• This results in the formation of active site.

Active site:

• Active site is the part of enzyme tertiary structure that binds with the substrate and carries the reaction.
• It contains catalytic groups that are involved in formation and degradation of bonds
• Active site is formed by the interaction of many aminoacids that are present far in the linear structure of enzyme but as result of folding, and tertiary structure formation creates specific binding site for the substrate
• To inhibit the enzyme activity there are inhibitor proteins that has the structure equal to substrate and thus it can bind to the enzyme active site and inhibit the reaction.

Substrate specificity:

• Substrate is bound to enzyme active site by multiple weak interactions.
• Interactions which are involved are electrostatic interaction, hydrogen bonding, van der waals interaction, hydrophobic interactions
• Substrate should have a matching structure to the enzymes active site.
• Some enzyme assume the shape only when the substrate fit and this is called as induced fit

Enzyme need to be in perfect conformation for the active site to bind to its specific substrate molecule. Any of the conformational changes results in inactivation of the enzymes. Inhibitors are proteins that have similar structure of substrate when inhibitory proteins bind to the enzyme active site the enzyme becomes inactive. Thus tertiary structure, active site and substrate specificity influence the enzyme function.