Amino acids

Amino acids are organic molecules serving as the fundamental building blocks of proteins, linked via peptide bonds to form polypeptide chains whose sequence dictates protein primary structure.[1][2][4] There are 20 standard α-amino acids incorporated into proteins, each distinguished by its unique side chain (R group) that influences polarity, charge, and hydrophobicity, thereby determining higher-order protein structures like α-helices, β-sheets, and tertiary folds essential for function.[2][3][5][6] Proteins perform diverse roles including catalysis as enzymes, structural support (e.g., collagen), transport, and signaling, all reliant on precise amino acid sequences encoded by DNA via mRNA and tRNA in ribosomes.[1][3][4][9] Nine amino acids (e.g., valine, leucine, isoleucine) are essential and must be dietary, while others like alanine and glycine are synthesized endogenously.[2][4] Aberrant amino acid sequences from mutations underlie diseases such as sickle cell anemia (valine-for-glutamic acid substitution in hemoglobin) or metabolic issues like phenylketonuria from phenylalanine hydroxylase deficiency.[2][5] Amino acids themselves are not therapeutic targets like receptors or enzymes; instead, drugs typically modulate specific proteins composed of them.[1][2][4]

Other names

α-amino acidsproteinogenic amino acidsbuilding blocks of proteins