Lecture Notes: Enzymes in Biochemistry

Introduction

• Part of a biochemistry playlist for MCAT, D80, Ornate exams.
• Previous topics covered: amino acids, peptide bonds, protein structures, conjugated proteins, and protein denaturation.

Protein Basics

• Proteins are composed of polypeptides made from amino acids.
• Types of peptides based on amino acid count:
  • Dipeptide: 2 amino acids
  • Tripeptide: 3 amino acids
  • Oligopeptide: Few amino acids
  • Polypeptide/Protein: Many amino acids
• Protein Structures:
  • Primary: Sequence of amino acids
  • Secondary: Includes alpha-helix and beta-pleated sheets
  • Tertiary: 3D structure
  • Quaternary: Combination of two or more tertiary structures

Conjugated Proteins

• Composed of a protein and a prosthetic group.

Peptide Bonds

• Formed by removing an H from one amino acid and an OH from another, releasing water.
• Peptides can be broken down by hydrolysis, especially in the presence of water.
• Enzymes like trypsin and chymotrypsin are hydrolases that break down peptide bonds in water.

Enzymes Overview

• Definition: Proteins that act as catalysts to speed up chemical reactions without being consumed.
• Function: Lower activation energy while maintaining equilibrium and thermodynamic properties.
• Specificity: Enzymes are specific to particular reactions or classes of reactions.
• Characteristics:
  • Not altered or consumed in the reaction
  • Do not change the final destination or equilibrium of the reaction
  • Do not alter the thermodynamics or overall free energy (ΔG)

Enzyme Analogy

• Enzymes are compared to airplanes for traveling from California to New York:
  • Without enzymes (airplane), each individual would drive separately, using more time and energy.
  • Enzymes lower activation energy like an airplane makes travel faster and easier.
• Graphical Representation:
  • Initial and final states of a reaction
  • Activation energy shown as the distance between initial state and the peak of energy required
  • Enzymes lower this peak, reducing the required activation energy.

Conclusion

• Enzymes facilitate reactions but do not change the endpoints or overall energy change.
• Understanding enzyme function includes knowing reactions like hydrolysis and types of enzymes like hydrolases.

Next Topics

• Enzyme nomenclature
• Enzyme kinetics and Michaelis-Menten graphs

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