Enzymology Overview and Classification

Enzymology Overview

• Enzymes are specific biological proteins that catalyze biochemical reactions without altering equilibrium.
• Present in all body tissues, especially serum post cellular injury.

Enzyme Classification

• Oxidoreductases: Catalyze removal/addition of electrons (redox reactions).
• Transferases: Transfer chemical groups (other than hydrogen) between substrates.
• Hydrolases: Split bonds by adding water (hydrolytic reactions).
• Lyases: Remove groups from substrates without hydrolysis, forming double bonds.
• Isomerases: Catalyze reorganization of molecular structures.
• Ligases: Join two molecules with covalent bonds.

Enzyme Structure

• Primary Structure: Sequence of amino acids.
• Secondary Structure: Twisting of polypeptide chains.
• Tertiary Structure: Folding due to structural cavities.
• Quaternary Structure: Arrangement of multiple polypeptide units.

Isoenzymes and Isoforms

• Isoenzymes: Different forms of an enzyme catalyzing the same reaction.
• Isoforms: Variants due to post-translational modifications.

Enzyme Activity Components

• Cofactors: Non-protein molecules essential for enzyme function.
• Activators: Inorganic cofactors (e.g., Ca, Mg, Zn) enhancing enzyme activity.
• Coenzymes: Organic cofactors, for example, NAD.

Enzyme Kinetics

• Enzymes reduce activation energy required for biochemical reactions.
• Reaction velocity relates to substrate concentration according to Michaelis-Menten kinetics.

Types of Inhibitors

• Competitive Inhibitors: Compete with substrate for active site.
• Non-competitive Inhibitors: Bind to an alternative site affecting enzyme function.
• Uncompetitive Inhibitors: Bind only to the enzyme-substrate complex.

Factors Influencing Enzyme Reactions

• Substrate Concentration: High levels can cause denaturation.
• Enzyme Concentration: Affects reaction rate until saturation.
• pH: Optimum 7.0-8.0; deviations cause denaturation.
• Temperature: Higher temperatures increase reaction rates but can lead to denaturation.

Clinical Significance of Enzymes

• Elevated enzyme levels often indicate tissue damage or disease.
• Specific enzymes assist in diagnosing conditions such as myocardial infarction and liver diseases.

Key Enzymes and Their Clinical Significance

• Creatine Kinase (CK):

  • Found primarily in muscle tissue, heart, and brain.
  • Elevated levels significant for myocardial infarction.

• Lactate Dehydrogenase (LDH):

  • Catalyzes lactate to pyruvate interconversion.
  • Clinical indicator of tissue damage or disease across various organs.

• Aspartate Aminotransferase (AST):

  • Involves the transfer of amino groups, primarily found in liver and heart.
  • Elevated in liver and skeletal muscle disorders.

• Alkaline Phosphatase (ALP):

  • Involved in hydrolysis of phosphate esters.
  • Clinical significance in liver and bone diseases.

• Amylase:

  • Hydrolyzes starch and glycogen into simple sugars.

Assay for Enzyme Activity

• Employ various methodologies for accurately measuring enzyme levels.
• Certain enzymes stable for several days post-collection under refrigeration; hemolysis affects results.

Reference Ranges

• CK: Male 46-171 U/L; Female 34-145 U/L at 37°C.
• LDH: 125-220 U/L at 37°C.
• AST: 5-35 U/L at 37°C.
• ALP: 42-128 U/L at 30°C for ages 20-50 years.

Use these key points for a comprehensive understanding of enzymatic functions, behaviors, and clinical implications in medical settings.

Dive into the fascinating world of enzymes with this quiz. Explore key concepts such as enzyme classification, structure, and the significance of isoenzymes. Assess your understanding of how these biological catalysts function and their roles in biochemical reactions.