The key difference between active site and binding site is that an active site aids the catalysis of a chemical reaction whereas a binding site aids on the binding of a ligand to a large molecule.
A binding site is a region on a protein, DNA or RNA, to which a ligand can bind. Enzymes are proteins. An active site is a region on an enzyme to which the substrates can bind in order to undergo a chemical reaction. This specific region also has a binding site along with a catalytic site. Therefore, binding sites aid only in the binding of a ligand to a large molecule whereas active sites aid both the binding of a ligand to a large molecule while letting it undergo a catalyzed chemical reaction.
CONTENTS
1. Overview and Key Difference
2. What is Active Site
3. What is Binding Site
4. Side by Side Comparison – Active Site vs Binding Site in Tabular Form
5. Summary
What is Active Site?
The active site is a region on an enzyme to which the substrates of a chemical reaction bind in order to undergo a catalyzed chemical reaction. this region is consist of two sub-regions as a binding site and catalytic site. The binding site contains some residues that can help the binding of the substrate (reactants) on to the enzyme. The catalytic site helps in catalyzing the chemical reaction. Moreover, this region is very small when compared to the whole volume of the enzyme; approximately 10-20% of the whole volume of the enzyme.
Figure 01: The Binding Site and Catalytic Site of an Active Site
Usually, the active site contains 3-4 amino acids. the rest of the amino acids in the enzyme involved in maintaining the tertiary structure of the enzyme. More importantly, an active site has a specific design which can fit with a specific substrate. Therefore, these enzymes react with only particular substrates. But sometimes, enzymes need cofactors for their function. The major function of the active site is to reduce the activation energy of a chemical reaction, thereby, to increase the reaction rate.
What is Binding Site?
Binding site is a region on a protein, DNA or RNA to which ligands can bind. There, the ligand can form a chemical bond with this site. These regions show specificity; a particular ligand will bind to a particular binding site. Therefore, this site is a measure of the types of ligands that can bind with a molecule.
Furthermore, we often use these regions for the functional characterization of biomolecules. For example, we can characterize the functionality of an active site through its binding site. Moreover, in the case of DNA, the specific type of binding site is the transcription factor binding site present on the DNA.
What is the Difference Between Active Site and Binding Site?
Active site is a region on an enzyme to which the substrates of a chemical reaction bind in order to undergo a catalyzed chemical reaction whereas binding site is a region on a protein, DNA or RNA, to which ligands can bind. This is the key difference between active site and binding site. Moreover, the active sites are present on enzymes, and they help to increase the reaction rate of a particular chemical reaction via decreasing the activation energy barrier of that reaction. Binding sites, on the other hand, are responsible for the binding of a specific ligand with a particular molecule.
The below infographic presents the difference between active site and binding site in tabular form.
Summary – Active Site vs Binding Site
Active sites are regions on enzymes that can increase the reaction rate of a chemical reaction via reducing the activation energy barrier of that reaction. A binding site is any region to which a ligand can bind. Active site also contains a binding site. The difference between active site and binding sites lies upon the existence and functionality. Therefore, the key difference between active site and binding site is that an active site aids the catalysis of a chemical reaction whereas a binding site aids on the binding of a ligand to a large molecule.
Reference:
1. “Active Site.” Wikipedia, Wikimedia Foundation, 24 July 2018. Available here
2. “Binding Site.” Wikipedia, Wikimedia Foundation, 28 Aug. 2018. Available here
Image Courtesy:
1.”Enzyme structure”By Thomas Shafee – Own work, (CC BY 4.0) via Commons Wikimedia