glycineextended

Glycineextended is a descriptive term used in biochemistry and molecular biology to refer to molecules that bear an extension composed of glycine residues. It is not a formally defined term in major databases, and its exact meaning depends on the context. Generally, glycine extensions are short or long sequences of glycine appended to the N- or C- terminus of a protein, peptide, or synthetic construct.

In protein engineering, glycine-rich linkers are used to connect domains because glycine provides high flexibility and low conformational constraint. Such linkers may be described as glycineextended when the glycine-rich region is a distinctive feature of the construct, helping to reduce steric hindrance between domains and to improve expression or folding in some cases.

In peptide synthesis or labeling, a glycine extension may serve as a spacer to improve solubility, enhance separation during purification, or provide a handle for chemical modification or affinity tagging. In sequence data, the term may appear to indicate that the observed molecule includes a terminal glycine extension due to processing or post-translational modification.

Benefits and caveats: glycine extensions can increase solubility and flexibility and can aid certain modifications or purifications. However, they may introduce unstructured regions that are susceptible to proteolysis or can affect the stability, folding, or activity of the molecule.

See also: glycine, glycine-rich linker, peptide linker, fusion protein, terminal modification.