Proteins: Structure, Functions, and Denaturation

Proteins

• Structure:
  • Primary structure: sequence of amino acids
  • Secondary structure: α-helix, β-pleated sheet, and random coil
  • Tertiary structure: 3D shape of a protein
  • Quaternary structure: arrangement of subunits
• Functions:
  • Enzymes: catalyze reactions
  • Transport: transport molecules and ions
  • Storage: store and release molecules
  • Regulation: regulate metabolic pathways
  • Defense: immune system proteins
• Denaturation:
  • Unfolding of protein structure
  • Caused by heat, pH, and chemicals
  • Loss of biological function

Lipid Metabolism

• Fatty Acid Oxidation:
  • β-Oxidation: breakdown of fatty acids into acetyl-CoA
  • Electron transport chain: generation of ATP
• Fatty Acid Synthesis:
  • De novo synthesis: synthesis of fatty acids from acetyl-CoA
  • Fatty acid synthase complex: enzyme complex involved
• Triacylglycerol Metabolism:
  • Triacylglycerol synthesis: esterification of glycerol and fatty acids
  • Lipolysis: breakdown of triacylglycerols into fatty acids and glycerol

Enzymology

• Characteristics:
  • High specificity for substrates
  • Optimal temperature and pH
  • Inactivation by denaturation
• Kinetics:
  • Michaelis-Menten equation: describes enzyme-substrate interaction
  • Km: Michaelis constant, measure of enzyme-substrate affinity
  • Vmax: maximum reaction rate
• Inhibition:
  • Competitive inhibition: inhibitor binds to active site
  • Non-competitive inhibition: inhibitor binds to allosteric site
  • Uncompetitive inhibition: inhibitor binds to enzyme-substrate complex

Metabolic Pathways

• Glycolysis:
  • Breakdown of glucose into pyruvate
  • Anaerobic: no oxygen required
  • Produces ATP and NADH
• Citric Acid Cycle (Krebs Cycle):
  • Breakdown of acetyl-CoA into CO2
  • Produces ATP, NADH, and FADH2
  • Electron transport chain: generates ATP
• Pentose Phosphate Pathway:
  • Generation of NADPH and pentoses
  • Important for nucleic acid synthesis and antioxidant defense

Proteins

• Primary structure of a protein is the sequence of amino acids
• Secondary structure includes α-helix, β-pleated sheet, and random coil
• Tertiary structure refers to the 3D shape of a protein
• Quaternary structure is the arrangement of subunits

Protein Functions

• Enzymes catalyze reactions
• Transport proteins transport molecules and ions
• Storage proteins store and release molecules
• Regulatory proteins regulate metabolic pathways
• Defense proteins are involved in the immune system

Denaturation

• Unfolding of protein structure resulting in loss of biological function
• Caused by heat, pH, and chemicals

Lipid Metabolism

• Fatty acid oxidation involves β-oxidation, breaking down fatty acids into acetyl-CoA
• Electron transport chain generates ATP during fatty acid oxidation

Fatty Acid Synthesis

• De novo synthesis involves the synthesis of fatty acids from acetyl-CoA
• Fatty acid synthase complex is the enzyme complex involved in fatty acid synthesis

Triacylglycerol Metabolism

• Triacylglycerol synthesis involves the esterification of glycerol and fatty acids
• Lipolysis breaks down triacylglycerols into fatty acids and glycerol

Enzymology

• Enzymes have high specificity for substrates
• Enzymes have optimal temperature and pH
• Enzymes can be inactivated by denaturation

Enzyme Kinetics

• Michaelis-Menten equation describes enzyme-substrate interaction
• Km represents the Michaelis constant, a measure of enzyme-substrate affinity
• Vmax represents the maximum reaction rate

Enzyme Inhibition

• Competitive inhibition occurs when an inhibitor binds to the active site
• Non-competitive inhibition occurs when an inhibitor binds to an allosteric site
• Uncompetitive inhibition occurs when an inhibitor binds to the enzyme-substrate complex

Metabolic Pathways

• Glycolysis breaks down glucose into pyruvate
• Glycolysis is an anaerobic process, requiring no oxygen
• Glycolysis produces ATP and NADH

Citric Acid Cycle (Krebs Cycle)

• Citric acid cycle breaks down acetyl-CoA into CO2
• Citric acid cycle produces ATP, NADH, and FADH2
• Electron transport chain generates ATP during citric acid cycle

Pentose Phosphate Pathway

• Pentose phosphate pathway generates NADPH and pentoses
• Pentose phosphate pathway is important for nucleic acid synthesis and antioxidant defense

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