Enzymes Flashcards

Enzymes Overview

• Enzymes are proteins that act as catalysts, speeding up chemical reactions by lowering activation energy without being consumed.
• Each enzyme binds to a specific substrate, forming an enzyme-substrate complex during the reaction.

Key Terms

• Substrate: The molecule an enzyme acts upon.
• Product: The substance produced after the chemical reaction.
• Active Site: The portion of the enzyme where the substrate binds and the reaction occurs.

Reaction Dynamics

• Activation Energy: The energy needed to initiate a reaction.
• Denaturation: The process where proteins lose their functional structure due to extreme pH, salt concentration, or temperature changes.

Metabolic Pathways

• Metabolic Pathway: Series of enzymatic reactions that build (anabolic) or break down (catabolic) molecules.
• Anabolic Pathway: Involves constructing larger molecules from smaller units.
• Catabolic Pathway: Involves breaking down larger molecules into smaller components.

Energy and Reactions

• Endergonic Reactions: Require energy input to proceed.
• Exergonic Reactions: Release energy during the process.

Energy Carrier

• ATP (Adenosine Triphosphate): Major energy currency in cells used in many metabolic processes, including enzyme-driven reactions.

Catalyst Functions

• Catalyst: A substance that accelerates a chemical reaction without undergoing permanent chemical change.
• Biological Catalyst: Often refers to enzymes that enhance biological reactions.

Enzyme Action Models

• Lock and Key Hypothesis: Suggests that a substrate fits perfectly into the enzyme's active site.
• Induced Fit Hypothesis: Proposes that the enzyme's active site adjusts to better fit the substrate upon binding.

Optimal Conditions

• Optimum Activity: Ideal conditions for maximum enzyme efficiency.
• Optimum pH: The specific pH level at which an enzyme operates best.
• Optimum Temperature: The best temperature for enzyme activity to maximize reaction rates.

Factors Influencing Enzymatic Activity

• Limiting Factor: A scarce resource that can slow down the rate of reaction.
• Cofactors: Essential molecules (metal ions or organic coenzymes) required for enzyme function.
• Coenzymes: Small organic molecules, often derived from vitamins, that assist enzyme catalysis.

Enzyme Structure

• Apoenzyme: The protein component of an enzyme that needs a cofactor to be active.
• Holoenzyme: The fully active form of an enzyme that contains its cofactor(s).
• Prosthetic Group: A non-protein component that permanently attaches to and is essential for the enzyme's function.

Inhibition Mechanisms

• Competitive Inhibition: Occurs when a substance mimics the substrate's structure and competes for the active site.
• Non-competitive Inhibition: Involves a substance binding to a different location on the enzyme, altering its shape and function.

Types of Enzymes

• Catalase: An enzyme found in living organisms that breaks down hydrogen peroxide into water and oxygen.
• Intracellular Enzymes: Enzymes that function within cells.
• Extracellular Enzymes: Enzymes that act outside their production site, e.g., digestive enzymes.

Reaction Parameters

• Specificity: Refers to the ability of an enzyme to catalyze only one type of reaction.
• Substrate Concentration: The concentration level of substrates available for enzyme reactions.
• Enzyme Concentration: The amount of enzyme present in a solution, affecting reaction rates.