Enzymes and Catalysts Overview

Enzymes and Catalysts

• Enzymes are biological catalysts that accelerate biochemical reactions within living organisms.
• Catalysts increase reaction rates without undergoing permanent changes themselves.
• Enzymes play critical roles in respiration, digestion, muscle and nerve function.

Enzyme Properties

• Most enzymes are protein molecules, constructed from chains of amino acids.
• Enzyme-catalyzed reactions typically occur under mild conditions, well below 100°C and at neutral pH.
• Enzymes exhibit specificity due to the shape of their active sites, which bind to specific substrates.

Enzyme Components

• Active site: The region of an enzyme responsible for binding to a substrate and catalyzing a reaction.
• Substrate: The molecule upon which an enzyme acts, serving as the starting material for a chemical reaction.
• Enzyme-substrate complex: A temporary intermediate formed when an enzyme binds to its substrate.
• Product: The molecule produced at the end of a chemical reaction catalyzed by an enzyme.

Enzyme Structure and Components

• Apoenzyme (apoprotein): The protein component of an enzyme requiring a cofactor for activity.
• Holoenzyme: The complete, active enzyme consisting of an apoenzyme and its cofactor(s).
• Cofactors: "Helper molecules" (inorganic or organic) that aid enzyme catalysis.

Types of Cofactors

• Prosthetic groups: Tightly bound cofactors essential for enzyme activity. Examples include heme.
• Coenzymes: Cofactors that bind to an enzyme only during catalysis, detaching afterwards. NAD+ is a common coenzyme.
• Metal ions: Essential for certain enzyme activities, contributing to catalysis by attracting or donating electrons. Metalloenzymes contain metal ions as cofactors.

Enzyme Specificity Models

• Lock-and-key model: The enzyme and substrate have complementary shapes, fitting together like a key in a lock.
• Induced fit model: The active site of the enzyme adapts its shape to perfectly fit the substrate upon binding.

Enzyme Classes

• Oxidoreductases: Catalyze electron transfer between molecules, facilitating oxidation and reduction reactions.
• Transferases: Transfer functional groups (e.g., hydroxyl, amino) between molecules.
• Hydrolases: Catalyze the cleavage of bonds using water, often involved in digestion. Examples include amylase, lipase and protease.
• Isomerases: Catalyze structural rearrangements within a single molecule, creating isomers.

Explore the fascinating world of enzymes and catalysts in this quiz. Learn about the properties, components, and roles of enzymes in biochemical reactions, digestion, and more. Test your knowledge on how these biological catalysts work and their importance in living organisms.