Overview of Enzyme Kinetics and Inhibition

Enzyme Kinetics

Basic Concepts of Enzyme Action

Enzymes are biological catalysts that accelerate chemical reactions in living organisms. Understanding their kinetics is essential for studying metabolic pathways and physiological regulation.

• Substrate: The molecule upon which an enzyme acts.

• Enzyme-Substrate Complex: Temporary association formed during the reaction.

• Product: The molecule(s) resulting from the enzymatic reaction.

General Reaction:

• E + S → ES → E + P

Key Terms:

• Active Site: Region on the enzyme where substrate binds.

• Transition State: High-energy state during the reaction.

Michaelis-Menten Equation:

$v = \frac{V_{max}[S]}{K_m + [S]}$

• v: Initial reaction velocity

• Vmax: Maximum velocity

• Km: Michaelis constant (substrate concentration at half Vmax)

Enzyme Inhibition

Enzyme inhibitors are molecules that decrease or halt enzyme activity. They are important in regulating metabolic pathways and as drug targets.

• Competitive Inhibition: Inhibitor competes with substrate for the active site.

• Non-competitive Inhibition: Inhibitor binds elsewhere, altering enzyme function.

• Uncompetitive Inhibition: Inhibitor binds only to the enzyme-substrate complex.

Type of Inhibition	Effect on Vmax	Effect on Km
Competitive	No change	Increases
Non-competitive	Decreases	No change
Uncompetitive	Decreases	Decreases

Acids and Bases

Definitions and Properties

Acids and bases are fundamental chemical species in physiology, affecting enzyme activity, cellular function, and metabolic processes.

• Acid: Substance that donates protons (H+).

• Base: Substance that accepts protons.

• pH: Measure of hydrogen ion concentration.

pH Equation:

$pH = -\log[H^+]$

• Low pH: Acidic

• High pH: Basic

Buffer Systems: Help maintain stable pH in biological systems.

Examples and Applications

• Enzyme activity is often optimal at specific pH ranges.

• Blood pH is tightly regulated (normal range: 7.35–7.45).

Additional info:

• Enzyme kinetics and inhibition are foundational topics in biochemistry and physiology, relevant for understanding metabolic regulation and drug mechanisms.

• Acid-base balance is crucial for homeostasis in all organ systems.