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Lecture 13: Functional and Exceptional peptides - Coggle Diagram
Lecture 13: Functional and Exceptional peptides
Carnosine
• A dipeptide of β-alanine and histidine
• The amino group is bonded to the β-carbon of alanine
Function It is highly concentrated in muscle and brain tissues, for Protection of cells from ROS (radical oxygen species) & peroxides and contraction of muscle
Also called: β-alanyl-L-histidine
Glutathione
Tripeptide, consists of:
Glutamate
Cysteine
Glycine
Thiol group of cysteine is the functional group of the glutathione as a whole
Called γ-Glutamate because the carboxylic group in the R group (which is attached to the carbon designated as C-γ ) makes the peptide bond with the amino group of cysteine rather than the carboxyl group attached to Cα.
Function:
• It scavenges oxidizing agents by reacting with them.
• Two molecules of the reduced glutathione molecules form the oxidized form of glutathione by forming a disulfide bond between
Also called: γ-glutamyl-L-cysteinylglycine
Enkephalins
Found in the brain, and function as analgesics (pain relievers).
The aromatic side chains of tyrosine and phenylalanine play a role in their activities.
Two pentapeptides
Met-enkephalin: Tyr-Gly-Gly-Phe-Met
Leu-enkephalin: Tyr-Gly-Gly-Phe-Leu
Oxytocin and vasopressin
Hormones with cyclic structures due to S-S link between Cys (1-6 disulfide bond).
Both have amide group at the C-terminus.
Both contain nine residues, but different in two:
• Oxytocin has isoleucine (3rd) and leucine (8th).
AAs sequence: Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly
• Vasopressin has phenylalanine (3rd) and arginine (8th).
AAs sequence: Cys-Tyr-Phe-Gln-Asn-Cys-Pro-Arg-Gly
Aspartame
It is a methyl ester: Aspartate + Phenylalanine + Methanol
Also called: L-Aspartyl-L-phenylalanine
Dipeptide