Gammaglutamyl

Gamma-glutamyl refers to a type of chemical linkage in which the gamma-carboxyl group of the amino acid glutamate forms an amide bond with the amino group of another molecule. This gamma-glutamyl linkage is distinct from the more common alpha-peptide bonds that link amino acids through their alpha-carboxyl groups in proteins. In biochemistry, gamma-glutamyl peptides are examples of this linkage.

Common gamma-glutamyl-containing compounds include gamma-glutamylcysteine and glutathione, the latter being a gamma-glutamylcysteinylglycine. Glutathione biosynthesis begins with the formation of gamma-glutamylcysteine via gamma-glutamylcysteine synthetase, followed by the addition of glycine to form glutathione through glutathione synthetase. The gamma-glutamyl bond is central to the structure of these molecules and to their biological roles in redox balance and cellular protection.

Biologically, the gamma-glutamyl cycle describes a series of reactions involving the transfer and recycling of the gamma-glutamyl moiety, contributing to amino acid transport and homeostasis. The enzyme gamma-glutamyl transpeptidase (GGT) catalyzes the transfer of the gamma-glutamyl group from glutathione to receptor amino acids or peptides, a key step in this cycle. GGT is membrane-associated and widely used as a clinical marker.

Clinically, elevated gamma-glutamyl transferase activity in blood is commonly associated with liver or biliary tract disorders, alcohol use, or pancreatitis. GGT levels are routinely measured alongside other liver enzymes to assess hepatic function and potential biliary obstruction.