5-oxoproline

5-ox·o·pro·line (Glp),

(ok'kō-prō'lēn), A keto derivative of proline that is formed nonenzymatically from glutamate, glutamine, and γ-glutamylated peptides; it is also produced by the action of γ-glutamylcyclotransferase; elevated levels of 5-oxoproline are often associated with problems of glutamine or glutathione metabolism. Synonym(s): 5-pyrrolidone-2-carboxylic acid, pyroglutamic acid, pyrrolidone-5-carboxylate