Difference Between Substrate Specificity and Bond Specificity

The key difference between substrate specificity and bond specificity is that substrate specificity is the ability of an enzyme to choose the exact substrate it can bond with from a group of similar compounds whereas bond specificity is the ability of an enzyme to choose substrates having similar bonds and similar structures.

The terms substrate specificity and bond specificity come under the field of biochemistry, regarding the activity of enzymes. We can define an enzyme as a biological catalyst. That means, enzymes are compounds that can enhance the rate of biological functions that take place in cells, but they are not consumed during the function. The term specificity refers to the way a particular enzyme bonds with a particular substrate.

1. Overview and Key Difference
2. What is Substrate Specificity
3. What is Bond Specificity
4. Side by Side Comparison – Substrate Specificity vs Bond Specificity in Tabular Form
5. Summary

What is Substrate Specificity?

Substrate specificity is the ability of an enzyme to bind with a particular substrate. This is also named as absolute specificity. This type of specificity is very high because the enzymes are specific to only one particular substrate and one reaction as well.

For example, lactase is an enzyme that can only hydrolyze beta-1,4-glycosidic bonds in lactose sugars. This reaction gives only glucose and galactose and is the only reaction that lactase enzyme involves in. Similarly, maltase is an enzyme that can act on alpha-1,4-glycosidic bonds in maltose to produce glucose molecules.

What is Bond Specificity?

Bond specificity is the ability of an enzyme to bind with a particular type of substrate that has similar structures and similar bonds. This is also known as relative specificity. The common types of chemical bonds on which the enzymes act on include peptide bonds, glycosidic bonds, ester bonds, etc.

For example, the enzyme known as alpha-amylase acts on alpha-1,4-glycosidic bonds to hydrolyze them (these bonds are present in starch and glycogen). Therefore, the enzyme is specific to the chemical bond (glycosidic bond) but not to the substrate.

What is the Difference Between Substrate Specificity and Bond Specificity?

We can define an enzyme as a biological catalyst. The term specificity refers to the way that a particular enzyme bonds with a particular substrate. The key difference between substrate specificity and bond specificity is that substrate specificity refers to the ability of an enzyme to choose the exact substrate it can bond with from a group of similar compounds whereas bond specificity refers to the ability of an enzyme to choose substrates having similar bonds and similar structures.

In other words, substrate specificity describes the binding of a particular enzyme with a particular substrate to undergo a particular reaction while bond specificity describes the binding of an enzyme with any substrate that has a particular bond (not specific to a particular substrate). For example, lactase is an enzyme that can hydrolyze only the beta-1,4-glycosidic bonds in lactose sugars. Similarly, alpha-amylase acts on alpha-1,4-glycosidic bonds to hydrolyze them (these bonds are present in starch and glycogen).

Below infographic summarizes the difference between substrate specificity and bond specificity.

Summary – Substrate Specificity vs Bond Specificity

The key difference between substrate specificity and bond specificity is that substrate specificity refers to the ability of an enzyme to choose the exact substrate it can bond with from a group of similar compounds whereas bond specificity refers to the ability of an enzyme to choose substrates having similar bonds and similar structures.

Reference:

1. “Substrate Specificity.” Substrate Specificity – an Overview | ScienceDirect Topics, Available here.
2. “What Is an Enzyme.” Easy Biology Class, Available here.