Amino Acids

Essential Amino Acids

These cannot be synthesized by the human body and must be obtained from the diet:

1. Histidine (His, H)

   • Important for growth and tissue repair.
   • Precursor to histamine.

2. Isoleucine (Ile, I)

   • Important for muscle metabolism.
   • Helps with energy production.
   • Important in transamination

3. Leucine (Leu, L)

   • Stimulates protein synthesis in muscle.
   • Helps with wound healing.
   • Important in transamination

4. Lysine (Lys, K)

   • Crucial for protein synthesis.
   • Helps with calcium absorption.

5. Methionine (Met, M)

   • A precursor to cysteine and taurine.
   • Important for metabolism and detoxification.
   • Crucial in methylation reactions and the synthesis of S-adenosylmethionine (SAM)

6. Phenylalanine (Phe, F)

   • Precursor to tyrosine, dopamine, norepinephrine, and epinephrine.
   • Important for brain function.

7. Threonine (Thr, T)

   • Important for collagen, elastin, and enamel protein production.
   • Plays a role in fat metabolism.

8. Tryptophan (Trp, W)

   • Precursor to serotonin and melatonin.
   • Important for sleep and mood regulation.
   • Vital for the synthesis of serotonin, melatonin, and niacin.

9. Valine (Val, V)

   • Important for muscle growth and tissue repair.
   • Helps with energy production.
   • Important in transamination

Non-Essential Amino Acids

These can be synthesized by the human body:

1. Alanine (Ala, A)

   • Helps convert glucose into energy.
   • Plays a role in muscle metabolism.
   • Important in the glucose-alanine cycle, which helps transport nitrogen from muscles to the liver.

2. Arginine (Arg, R)

   • Important for wound healing and immune function.
   • Precursor to nitric oxide.

3. Asparagine (Asn, N)

   • Important for the nervous system.
   • Helps in the synthesis of glycoproteins.

4. Aspartic Acid (Asp, D)

   • Helps in the citric acid cycle.
   • Important for hormone production and release.
   • Directly involved in the urea cycle, providing nitrogen for urea synthesis.

5. Cysteine (Cys, C)

   • Important for detoxification and antioxidant functions.
   • Helps form keratin (skin, hair, nails).
   • Role in Ammonia detoxification

6. Glutamic Acid (Glu, E)

   • Important for brain function and metabolism.
   • A precursor to gamma-aminobutyric acid (GABA).
   • Central to transamination, as it often serves as the amino group donor or acceptor.

7. Glutamine (Gln, Q)

   • Important for immune function and gut health.
   • Provides energy for rapidly dividing cells.

8. Glycine (Gly, G)

   • Important for collagen production.
   • Acts as a neurotransmitter.

9. Proline (Pro, P)

   • Important for collagen stability.
   • Plays a role in wound healing.

10. Serine (Ser, S)

    • Important for the synthesis of phospholipids.
    • Plays a role in the function of enzymes.

11. Tyrosine (Tyr, Y)

    • Precursor to dopamine, norepinephrine, and epinephrine.
    • Important for thyroid hormones.

Special Amino Acids

These have unique roles and are not part of the standard set of amino acids:

1. Selenocysteine (Sec, U)

   • Present in some enzymes, especially those involved in antioxidant functions.
   • Contains selenium, which is important for thyroid function.

2. Pyrrolysine (Pyl, O)

   • Found in some archaeal and bacterial proteins.
   • Plays a role in methane-producing organisms.

Amino acids are the building blocks of proteins. Each protein comprises a specific sequence of amino acids, which determines its structure and function. The sequence of amino acids in a protein is encoded by the corresponding sequence of nucleotides in the gene that encodes the protein. The 20 standard amino acids are joined by peptide bonds to form polypeptides, which fold into functional proteins.