1.4.2 Enzyme Specificity

Enzyme specificity is the ability of an enzyme to select a specific substrate from a group of similar compounds. This is due to the enzyme's active site being complementary in shape to the substrate it acts on.

• Enzyme specificity is a kinetic property that depends on the enzyme's structure. It includes changes in shape (conformational changes) that occur after the substrate binds to the enzyme.
• Specificity constant (kcat/Km) measures how efficiently an enzyme converts competing substrates.

Enzymes are selective catalysts, meaning different enzymes have varying levels of specificity:

• Some enzymes have absolute specificity, catalysing only one specific reaction.
• Other enzymes may have a preference for a particular chemical bond or functional group.

Types of Enzyme Specificity:

1. Absolute Specificity: The enzyme only catalyses a single reaction.
2. Group Specificity: The enzyme only acts on molecules with specific functional groups.
3. Linkage Specificity: The enzyme acts on a specific type of bond, regardless of other structural parts of the molecule.
4. Stereochemical Specificity: The enzyme only acts on a particular optical or stereoisomer (e.g., D- or L- forms of a compound).