Proteinogenic amino acids

Proteinogenic amino acids are the amino acids that are incorporated biosynthetically into proteins during translation. The word "proteinogenic" means "protein creating". Among the 20 standard amino acids, there are 9 essential amino acids for humans, as these cannot be synthesized by the human body and must be obtained from the diet. The proteinogenic amino acids are used by cells to synthesize proteins, which play critical roles in biological processes such as enzyme catalysis, cellular structure, and the regulation of tissue and organ function.

Overview

Proteinogenic amino acids are central to the process of protein synthesis, where they are linked together in specific sequences to form polypeptide chains. These chains fold into specific three-dimensional structures, or proteins, which carry out various functions in living organisms. The sequence of amino acids in a protein is determined by the sequence of nucleotides in the gene encoding that protein.

Classification

Proteinogenic amino acids can be classified in several ways, but one common method is by their nutritional requirement in humans:

• Essential amino acids: These cannot be synthesized de novo by the organism (at least not in sufficient quantities) and must be obtained from the diet. In humans, these include Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, and Valine.
• Non-essential amino acids: These can be synthesized by the human body and do not need to be obtained directly through the diet. They include Alanine, Asparagine, Aspartic acid, Glutamic acid, Serine, and others.

Additionally, there are a few amino acids that are considered conditionally essential, meaning that under certain conditions, such as illness or stress, the body cannot produce enough of them, and they must be obtained from the diet. These include Arginine, Cysteine, Glutamine, Tyrosine, Glycine, Proline, and Ornithine.

Biosynthesis

The biosynthesis of proteinogenic amino acids involves complex metabolic pathways. Most of the non-essential amino acids are synthesized from common metabolic precursors such as pyruvate, oxaloacetate, and alpha-ketoglutarate. Essential amino acids, on the other hand, are generally synthesized by plants and microorganisms through pathways that are not present in humans.

Function

Proteinogenic amino acids play a wide variety of roles in cellular processes. They are the building blocks of proteins, which are involved in virtually every cellular function, including:

• Structural components of cells and tissues
• Enzymes that catalyze biochemical reactions
• Signaling molecules and receptors
• Transport and storage of molecules
• Immune response

Genetic Code

The genetic code is the set of rules by which information encoded in genetic material (DNA or RNA sequences) is translated into proteins by living cells. The code defines how sequences of three nucleotides, called codons, specify which amino acid will be added next during protein synthesis. All 20 proteinogenic amino acids are encoded by at least one codon in the genetic code, with some amino acids being encoded by multiple codons.

See Also

• Amino acid
• Protein biosynthesis
• Genetic code
• Essential nutrients