Medical Lecture Notes

A BLOG FOR all medical students contains a lot of knowledge in beautiful perfect notes.

Monday, 8 January 2018



Image result for Peptides

Importance :

As major hormones e.g. insulin.In the nervous system as neurotransmitters or neuromodulators (e.g. enkephalins).Certain antibiotics e.g. Bacitracin and Polymyxinenkephalin .

Formation  : 

  • Peptide structure written from left to right starting from amino acid residue has free amino group (N-terminal)
  •  Peptides written using either three letter abbreviation e.g. ala, gly…. or one letter abbreviation (for long peptides).
  • The peptide bond is formed between the α–carboxyl group of one amino acid and the α-amino group of another to form water.
  • Peptide bonds formation require energy.
  • The name tri peptide means have three amino acid residues (not three peptide bonds).
  • The amino acid whose α-carboxyl group participated in the formation of peptide bond is termed amino acyl residue ( replace -ate or -ine by –yl e.g. alanyl, cysteinyl, tyrosine).


  • Optically active (by component of amino acids). 
  • Amphoteric properties: Depends on the present of dissociating groups in the side chains and on the acidic or basic R group.
  • Physiological Activity of Peptides 
  •  Glutathione= Y-glutamyl-cystenyl-glycine: Is tripeptide. Have the y-glutamate (as an unusual amino acid). Important in redox reactions in the Red Blood Cells (RBCs). 
  • Vasopressin (VP), anti diuretic hormone (ADH): Is non a peptide.  
  • Function: in contraction of smooth muscles (increase the blood pressure), and re-absorption of H2O.
  • Oxytocin: Non a peptide Hormone 
  • Function : contracts uterus (help delivery), and help release milk from lactating mammary glands.

No comments:

Post a Comment