There are 20 different types of amino acids commonly found in proteins.
Understanding Amino Acids
Amino acids are the fundamental building blocks of proteins, which are essential molecules in all living organisms. Each amino acid has unique chemical properties that contribute to the overall structure and function of proteins.
Key Features of Amino Acids
- Structure: Amino acids are organic compounds containing an amino group (-NH2), a carboxyl group (-COOH), and a unique side chain (R group) attached to a central carbon atom.
- Diversity: The 20 amino acids differ in their side chains, which vary in size, shape, charge, and chemical reactivity.
- Peptide Bonds: Amino acids link together via covalent peptide bonds to form long chains known as polypeptides.
The 20 Amino Acids
The 20 amino acids commonly found in proteins are listed below:
| Amino Acid | 3-Letter Code | 1-Letter Code |
|---|---|---|
| Alanine | Ala | A |
| Arginine | Arg | R |
| Asparagine | Asn | N |
| Aspartic acid | Asp | D |
| Cysteine | Cys | C |
| Glutamic acid | Glu | E |
| Glutamine | Gln | Q |
| Glycine | Gly | G |
| Histidine | His | H |
| Isoleucine | Ile | I |
| Leucine | Leu | L |
| Lysine | Lys | K |
| Methionine | Met | M |
| Phenylalanine | Phe | F |
| Proline | Pro | P |
| Serine | Ser | S |
| Threonine | Thr | T |
| Tryptophan | Trp | W |
| Tyrosine | Tyr | Y |
| Valine | Val | V |
Role in Protein Structure
- Primary Structure: The sequence of amino acids in a polypeptide chain determines the protein's primary structure.
- Secondary Structure: Local folding patterns, such as alpha-helices and beta-sheets, arise from interactions between nearby amino acids.
- Tertiary Structure: The overall three-dimensional arrangement of a polypeptide chain is stabilized by various interactions between the side chains of amino acids.
- Quaternary Structure: Some proteins consist of multiple polypeptide chains (subunits) that associate to form a functional protein complex.
Significance in Biological Functions
- Enzymes: Proteins that catalyze biochemical reactions.
- Structural Components: Proteins that provide structural support to cells and tissues (e.g., collagen, keratin).
- Transport Molecules: Proteins that carry substances within cells or throughout the body (e.g., hemoglobin).
- Antibodies: Proteins involved in the immune response, recognizing and neutralizing foreign invaders.
- Hormones: Proteins that regulate various physiological processes (e.g., insulin).
