Enzymes: Characteristics and Functions

Definition of Enzymes

• Enzymes are proteins that accelerate biochemical reactions without being consumed in the process.
• They function by forming an enzyme-substrate complex, leading to the production of specific end products.

Characteristics of Enzymes

• Enzymes are sensitive to environmental factors like temperature and pH; they require optimal conditions for efficiency.
• They remain unchanged after catalysis, allowing them to act on multiple substrate molecules over time.
• Highly specific in function, with active sites designed for particular substrate shapes, likened to a "lock-and-key" mechanism.

Lock and Key Hypothesis

• The "lock and key" hypothesis illustrates that each enzyme (lock) binds only to its specific substrate (key).
• This specificity ensures efficient biochemical reactions tailored to particular substrates.

Factors Affecting Enzyme Activity

• Temperature:

  • Each enzyme has an optimum temperature, usually around 37°C in humans, where it catalyzes reactions at maximum rates.
  • High temperatures can lead to denaturation, inactivating the enzyme.

• pH:

  • Enzyme activity is influenced by the acidity or alkalinity of its environment; each enzyme has an optimum pH.
  • Deviations from this pH can disrupt ionic and hydrogen bonds, altering the enzyme's structure and function.

• Substrate Concentration:

  • Increasing substrate concentration initially raises the reaction rate, up to a saturation point where all active sites are occupied.
  • Beyond saturation, increases in substrate have no effect on reaction rate.

Optimum Conditions

• Optimum Temperature: Temperature at which an enzyme functions best, usually correlating with the organism's normal body temperature.
• Optimum pH: Specific pH level that allows an enzyme to reach its peak activity; varies between different enzymes.

Commercial Applications of Enzymes

• Utilized in various industries:
  • Protease for meat tenderizers.
  • Lactase to reduce lactose in ice cream, preventing gritty texture.
  • Cellulase in cereal production and agar extraction from seaweed.

Types of Reactions

• Anabolic Reactions: Enzyme-catalyzed processes that build complex molecules from simpler ones, requiring energy input.
• Catabolic Reactions: Enzyme-catalyzed processes that break down complex molecules into simpler ones, releasing energy.

Enzyme Inhibitors

• Molecules that impede enzyme activity by binding to the enzyme and affecting its ability to catalyze reactions.

This quiz covers the fundamental concepts of enzymes, including their definition, characteristics, and mode of action. It delves into the 'lock and key' hypothesis, the specificity of enzymes to substrates, and the effects of temperature and pH on enzyme activity. Furthermore, it highlights the importance of optimum conditions for enzyme efficiency, along with commercial applications.