Categories: Proteins | Posttranslational modification A protein primary structure is a chain of amino acids. ... An overview of protein synthesis. ... A peptide bond is a chemical bond formed between two molecules when the carboxyl group of one molecule reacts with the amino group of the other molecule, releasing a molecule of water (H2O). ... Proteolysis is the directed degradation (digestion) of proteins by cellular enzymes called proteases or by intramolecular digestion. ... In chemistry racemization refers to partial conversion of one enantiomer into another. ... Acetylation describes a reaction, usually with acetic acid, that introduces an acetyl functional group into an organic compound. ... Categories: | | ... This article needs to be wikified. ... Pyroglutamate is an uncommon amino acid found in bacteriorhodopsin. ... A GPI anchor or glycosylphosphatidylinositol is a common posttranslational modification of the C-terminus of membrane-attached proteins. ... Lysine is one of the 20 amino acids normally found in proteins. ... In biochemistry, methylation refers to the replacement of a hydrogen atom (H) with a methyl group (CH3), regardless of the substrate. ... Acetylation describes a reaction, usually with acetic acid, that introduces an acetyl functional group into an organic compound. ... Hydroxylation is any chemical process that introduces one or more hydroxyl groups (-OH) into a compound (or radical) thereby oxidising it. ... Ubiquitin is a small regulatory protein that is ubiquitous in eukaryotes. ... Small Ubiquitin-related Modifier or SUMO proteins are a family of small proteins that are covalently attached to and detached from other proteins in cells to modify their function. ... Cysteine is a naturally occurring amino acid which has a thiol group and is found in most proteins, though only in small quantities. ... A disulfide bond (SS-bond), also called a disulfide bridge, is a strong covalent bond between two sulfhydryl (-SH) groups. ... Prenylation or isoprenylation is the addition of hydrophobic molecules to a protein to facilitate its attachment to the cell membrane. ... Serine is one of the 20 natural amino acids. ... Threonine is one of the 20 natural amino acids. ... Phosphorylation is the addition of a phosphate (PO4) group to a protein or a small molecule. ... Glycosylation is the process or result of addition of saccharides to proteins and lipids. ... Tyrosine (from the Greek tyros, meaning cheese, as it was first discovered in cheese), 4-hydroxyphenylalanine, or 2-amino-3(4-hydroxyphenyl)-propanoic acid, is one of the 20 amino acids that are used by cells to synthesize proteins. ... Phosphorylation is the addition of a phosphate (PO4) group to a protein or a small molecule. ... Asparagine is one of the 20 most common natural amino acids on Earth. ... Deamidation reaction of Asn-Gly (top right) to Asp-Gly (at left) or iso(Asp)-Gly (in green at bottom right). ... Glycosylation is the process or result of addition of saccharides to proteins and lipids. ... Aspartic acid, also known as aspartate, the name of its anion, is one of the 20 natural proteinogenic amino acids which are the building blocks of proteins. ... Deamidation reaction of Asn-Gly (top right) to Asp-Gly (at left) or iso(Asp)-Gly (in green at bottom right). ... Glutamate is the anion of glutamic acid. ... Arginine (Arg) is an α-amino acid. ... Citrullination or deimination is the term used for the post-translational modification of the amino acid arginine in a protein into the amino acid citrulline. ... In biochemistry, methylation refers to the replacement of a hydrogen atom (H) with a methyl group (CH3), regardless of the substrate. ... L-Proline is one of the twenty proteinogenic units which are used in living organisms as the building blocks of proteins. ... Hydroxylation is any chemical process that introduces one or more hydroxyl groups (-OH) into a compound (or radical) thereby oxidising it. ...