Amino acids are the building blocks of proteins. They contain both acidic and basic groups that allow them to polymerize and form peptide bonds, assembling into linear chains known as polypeptides or proteins. There are 20 common amino acids that make up proteins, which can be classified based on their variable R groups into nonpolar, aromatic, polar uncharged, positively charged, and negatively charged categories. Proteins perform a wide variety of important biological functions in the body as enzymes, structural components, binding proteins, hormones, and more.
3. Amino Acids:
Building Blocks of Protein
• Proteins are linear heteropolymers of -amino acids
• Amino acids have properties that are well-suited to carry
out a variety of biological functions
– Capacity to polymerize
– Useful acid-base properties
– Varied physical properties
– Varied chemical functionality
7. Amino Acids: Classification
Common amino acids can be placed in five basic
groups depending on their R substituents:
• Nonpolar, aliphatic (7)
• Aromatic (3)
• Polar, uncharged (5)
• Positively charged (3)
• Negatively charged (2)
20. Toxic Amino Acids
A search for compounds producing Yunnan
Sudden Unexplained Deaths found related to
eating a mushroom.
Trogia venenata Zhu LHalford, B. C+E News Feb 13, 2012
21. Which Form Occurs in Water ?
An amino acid contains both acidic (carboxylic acid fragment) and
basic (amine fragment) centres. The isomer on the right is a zwitterion.
23. Structure of a Simple Peptide
Ser-Gly-Tyr-Ala-Leu or SGYAL
24. Naming peptides:
start at the N-terminus
• Using full amino acid names
– Serylglycyltyrosylalanylleucine
• Using the three-letter code abbreviation
– Ser-Gly-Tyr-Ala-Leu
• For longer peptides (like proteins) the one-
letter code can be used
– SGYAL