γ-Glutamyltransferase Sample Clauses

γ-Glutamyltransferase. Children presenting with cholestasis in the neonatal and early infancy period have been differentiated into high or low GGT syndromes, utilising this enzyme as a marker of distinction between bile duct damage and hepatocellular inflammation. Xxxxxxxxx et al, showed a strong association between high GGT and biliary disease and a correlation between serum GGT and alkaline phosphatase (ALP) in liver disease suggesting that changes in the activity of GGT reflect principally alterations in biliary function, rather than damage to the parenchymal liver cells (Xxxxxxxxx et al. 1972). GGT is an enzyme that transfers gamma-glutamyl groups from peptides such as glutathione to other amino acids and has a potential role in the amino acid transport. GGT catalyses the transfer of the gamma-glutamyl moiety of glutathione to an acceptor, that may be an amino acid, a peptide or water (forming glutamate). GGT plays a key role in the gamma-glutamyl cycle, a pathway for the synthesis and degradation of glutathione and also for drug and xenobiotic detoxification. The enzyme is composed of a heavy and a light chain, which are derived from a single precursor protein (Figure 1), and is present in tissues involved in absorption and secretion such as kidneys, pancreas, spleen, heart, brain, but most notably in the hepatobiliary system (Kinlough et al. 2005).