Glutamyl transferase

Enzymes, measured in clinical laboratories, for which kits are available include y-glutamyl transferase (GGT), alanine transferase [9000-86-6] (ALT), aldolase, a-amylase [9000-90-2] aspartate aminotransferase [9000-97-9], creatine kinase and its isoenzymes, galactose-l-phosphate uridyl transferase, Hpase, malate dehydrogenase [9001 -64-3], 5 -nucleotidase, phosphohexose isomerase, and pymvate kinase [9001-59-6]. One example is the measurement of aspartate aminotransferase, where the reaction is followed by monitoring the loss of NADH ... 

Activities of glutamate-pyruvate transaminase (SGPT, GPT) (EC 2.6.1.2), L-y -glutamyl-transferase (y-GT) (EC 2.3.2.2) and level of triglycerides (TG) in serum, as well as levels of glutathione (GSH) and malondialdehyde (MDA) in the liver were determined. 

Gamma-glutamyl-transferase activity was determined according to "Monotest 10 y-GT neu" from Boehringer-Mannheim. 

The enzymes found in liver cells (Group I enzymes) include more than a dozen enzymes used in diagnostic laboratories, but those used most commonly are the transaminases (GOT and GPT), which continue to be the most widely used indicators of liver cell integrity. Enzymes found in the biliary cells (Group II) include alkaline phosphatase, glutamyl-transferase, leucine amniopeptidase and 3-nucleotidase. 

Another common liver disease, alcoholic liver damage produced by moderate to heavy alcoholic intake, is also reflected by an elevation of the serum GOT and GPT activities. The serim glutamyl transferase activity is reported to be a sensitive index of alcoholic intake and can serve to monitor persons on alcoholic withdrawal programs (60). The LD-5 isoenzyme arises mainly from liver tissue, but has a short half-life (61), which is about 1/5 and 1/2 of the half life of the transaminases, GPT and GOT respectively. Some authors consider that a normal LD-5 isoenzyme activity in a jaundiced patient is sufficient evidence to exclude primary liver disease and that obstruction is probably responsible for the jaundice (62). In hemolytic jaundice the LDH-1 and 2 isoenzymes are elevated. 

Cholestasis (increased total bilirubin, direct bilirubin, alkaline phosphatase, and y-glutamyl transferase)... 

Serum aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, y-glutamyl transferase, and bilirubin may be elevated in patients with hepatobiliary disease. 

ALT, alanine aminotransferase AST, aspartate aminotransferase GGT, gamma-glutamyl transferase INR, international normalized ratio LDH, lactate dehydrogenase PT, prothrombin time. 

Elevations of alkaline phosphatase, /glutamyl transferase, and total bilirubin in patients with cholestatic illness. 

Hepatic Effects. Liver function tests (serum bilirubin, alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, gamma-glutamyl transferase) completed in 11 hexachloroethane workers were within the normal range (Selden et al. 1994). Plasma hexachloroethane levels in these workers, who wore protective equipment, were 7.3 + 6.04 pg/L at the time of the tests (Selden et al. 1993). Mild skin and mucous membrane irritation were reported in the exposed group, suggesting that exposure may have been through either the inhalation or dermal routes of exposure. 

Hepatic Effects. Liver function tests (serum bilirubin, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transferase) were not affected in 11 hexachloroethane-exposed workers who wore protective clothing (Selden et al. 1993). 

Fig. 4.2 Hydrolytic activity of cauxin on 3-MBCG and proposed metabolic pathways for the conversion of 3-MBG to felinine in the cat kidney. The 3-MBCG (20 mM) was incubated with or without cauxin (1.5 mg/ml) at 38°C for 6 h, and the reaction mixtures were analyzed by thin layer chromatography with ninhydrin staining. y-GTP, y-glutamyl transferase RDP, renal dipeptidase a, 3-mercapto-3-methylbutyl formate b, 3-mercapto-3-methyl-l-butanol c, 3-methyl-3-methylthio-1-butanol and d, 3-methyl-3-(2-methyldisulfanyl)-l-butanol...

Alcohol consumption is very difficult to assess. There is widespread belief that individuals underreport their intake and there are no reliable laboratory tests available for definitive diagnosis of alcohol abuse. A combination of abnormalities in the plasma activity of gamma-glutamyl transferase (GGT or yGT), AST and reduction in erythrocyte mean cell volume (MCV) maybe useful and all are routine lab. tests. A potential marker of interest is carbohydrate-deficient transferrin (CDT) which is an abnormal isoform of serum transferrin arising due to defects in the attachment of carbohydrate chains to the protein core. Unfortunately, CDT is a somewhat specialized test, not performed by most laboratories. Other markers which have attracted some research interest are ethyl sulphate and ethyl glucuronide. Excretion in the urine of these metabolites occurs for up to 50 hours after binge drinking so they offer a useful index of recent heavy alcohol intake. 

Aside from the Maillard reaction, other covalent modifications of amino acids and proteins are possible within the caries lesion, which merit future investigation. For example, certain oral microorganisms excrete y-glutamyl transferases. These enzymes catalyse the formation of cross-links between glutamic acid and lysine residues of proteins. In addition, N-acyl amino acids are present in plaque, which adsorb to mineral surfaces. 

Cyclins Proteinkinase A Tryptophan oxygenase y-Glutamyl transferase... 

When we received her back she was on a low and peculiar dose of methadone, and it transpired that she had recently been reducing this by 2ml in the daily dosage every two weeks, at her own request. In the interview there was an obvious smell of alcohol, and assessment soon revealed that Sandra was drinking heavily every day, with her gamma glutamyl transferase coming back at several hundred international units per litre. 

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