Proteinogenic amino acid

Proteinogenic Amino Acid

A proteinogenic amino acid is an organic compound that serves as a building block for proteins. These amino acids are essential for the synthesis of proteins in living organisms. They are characterized by the presence of an amino group (-NH2) and a carboxyl group (-COOH) attached to a central carbon atom, known as the alpha carbon. Additionally, they have a side chain, also known as an R-group, which varies among different amino acids.

Classification

Proteinogenic amino acids can be classified into several categories based on their properties and functions. One common classification is based on the polarity of the side chain:

1. Nonpolar Amino Acids: These amino acids have hydrophobic side chains that do not interact with water molecules. Examples include glycine, alanine, valine, leucine, isoleucine, proline, methionine, and phenylalanine.

2. Polar Amino Acids: These amino acids have hydrophilic side chains that can form hydrogen bonds with water molecules. Examples include serine, threonine, cysteine, tyrosine, asparagine, and glutamine.

3. Positively Charged (Basic) Amino Acids: These amino acids have positively charged side chains at physiological pH. Examples include lysine, arginine, and histidine.

4. Negatively Charged (Acidic) Amino Acids: These amino acids have negatively charged side chains at physiological pH. Examples include aspartic acid and glutamic acid.

Functions

Proteinogenic amino acids play crucial roles in various biological processes:

1. Protein Synthesis: Amino acids are the building blocks of proteins. During protein synthesis, amino acids are linked together through peptide bonds to form polypeptide chains. The sequence of amino acids determines the structure and function of the protein.

2. Enzyme Catalysis: Some amino acids, such as histidine and serine, act as catalytic residues in enzymes. They participate in chemical reactions by donating or accepting protons or electrons.

3. Cell Signaling: Amino acids, such as glutamate and glycine, serve as neurotransmitters in the nervous system. They transmit signals between nerve cells, allowing for proper communication and coordination.

4. Metabolism: Amino acids are involved in various metabolic pathways. For example, phenylalanine is converted into tyrosine, which is further metabolized to produce important molecules such as dopamine, adrenaline, and thyroid hormones.

Importance in Nutrition

Proteinogenic amino acids are essential nutrients for humans and other animals. They cannot be synthesized by the body and must be obtained through dietary sources. A balanced diet should include all essential amino acids to support proper growth, development, and maintenance of bodily functions.

See Also

• Protein
• Peptide bond
• Enzyme
• Metabolism