Chemistry · MU Plovdiv

17. Peptides and proteins – classification, structure, properties, functions. Peptide hormones – examples and functions.

Inside: 14 sections · 12 labelled pictures · 35 flashcards · 10 min

Topic 17 of 26 in the MU Plovdiv syllabus for Chemistry (Medicine, Year 1). The free AceMed note covers it in 14 sections, about 1,375 words (10 min of reading), with 35 flashcards.

In this note

  1. Peptides and proteins.
  2. Peptide bond structure and stereochemistry.
  3. Methods for peptide synthesis - protecting groups and solid -phase synthesis.
  4. Solid-Phase Synthesis
  5. Examples of biologically important peptides: glutathione, enkephalin, vasopressin, oxytocin and insulin.
  6. High Yield
  7. Peptide Bond Properties
  8. Levels of Protein Structure
  9. Structural organisation of proteins.
  10. Structural elements of primary, secondary, tertiary and quaternary structure.
  11. Structure-Function Relationship in Proteins
  12. Edman method of protein sequencing.
  13. Methods for establishing the tertiary structure of proteins.
  14. Proteomics.

Peptides and proteins.

  • Building Blocks: Amino acids linked by peptide bonds (covalent bonds between the carboxyl group of one amino acid and the amino group of another).
  • Size: Peptides (2-50 amino acids) are smaller than proteins (50+ amino acids).
  • Structure: Proteins fold into specific 3D structures (primary, secondary, tertiary, qaternary) for function. Peptides may have some secondary structure.
  • Protein Functions: Enzymes, structural support, transport, antibodies, signaling.
  • Peptide Examples: Insulin, endorphins, glutathione.

Peptide bond structure and stereochemistry.

  • Peptide Bonds: Covalent bonds linking amino acids in peptides or proteins.
  • Formed via condensation reaction between:
  • Carboxyl group (-COOH) of one amino acid.
  • Amino group (-NH2) of another amino acid.
  • Structure:
  • Covalent bond formed between the carbon atom of the carboxyl group of one amino acid and the nitrogen atom of the amino group of another.
  • Results in the loss of a water molecule (condensation).
  • Creates a stable amide bond (-CO-NH-).
  • Characterized by partial double-bond character, restricting rotation around the bond.
  • This rigidity influences the folding and structure of proteins.
  • Stereochemistry:
  • Peptide bonds exhibit trans configuration, with the atoms on either side of the bond lying in a trans orientation, minimizing steric hindrance.
  • The peptide bond's geometry plays a crucial role in determining the overall shape and function of the protein.

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