In 1950 and 1952 Hahnes et al. observed that glutathione (r-glutamylcysteinylglycine) reacted with various amino-acids or peptides in the presence of an enzyme from kidney tissue to form new r-glutamyl peptide and cysteinylglycine, and confirmed that the reaction consisted of the transfer of the r-glutamyl group from glutathione (donor) to amino acids (acceptor). The enzyme catalyzing transpeptidation reaction was called r-glutamyl transpeptidase.
Nearly all the works of GGT in clinical applications have been reported since about 1965 GGT is highly evaluated as a diagnostic aid to diseases of hepatobiliary system such as hepatitis, liver cirrhosis, Iepatoma, metastatic carcinoma to the liver, cholecystitis and cholelithiasis, and of pancreas such as pancreatitis. This enzyme has received much attention in myocardial infarction, alcoholics, diabetes mellitus, and neurological diseases.
Glutathions had been used originally as substrate in determining GGT activity. This was later replaced by ?-glutamyl aminonitriles, r-glutamylanilide, r-glutamylnaphthylamide and glutamyl-p-nitro-anilide. A marked simplification was obtained as the results. Now´ the assy Iof GGT can be done in about5 minutes, though it needed 2 to 4 hours for the determination in loder days. This kinetic method is evaluated as a most rapid, simple and accurate one. The author reports normal serum GGT activity of Koreans by the method of Szesz.
1. Normal serum GGT activities in\healthy male and female Koreans in the 6 age groups are as follows. Numbers; in the parenthesis are cases of males and females studied. In the age groups 6~20 (25, 11), 21~30 (27, 43), 31~40 (50, 37), 41~50 (33, 25), 51~60.(21, 23), -and 61~80 (17, 14), mean yalues and normal ranges in male and female age-groups are 9.1, 3.9~13.3: 9.1, 5. 1~15-9: 11.3, 4.8~20.0:9.5, 5.0~18.9:11.9, 6.3~21.8:10.0, 5.2~18.4:13.4, 7.5~21.0:11.3, 6.6~16.2:13.9, 11.1~18.7:9.2, 4.3~16.6:12.7,6.1~19.8:9. 5, 4.8~13.1/ml respectively Mean values and normal ranges n total number of males (173 cases) and females (153 cases) are 12.1±7-7, 3.8~19.8:9.8?6.5, 3.3~16.3/ml respectively. Mean values of males are moderately higher than those of females.
2. Homolytic serum shows no, significant, change in GGT petivity.
3. Hyperbilirubinemia increases a little GGT activity but the increase can be excluded by using blank in this kinetic method.
4. Reproducibility is excellent judging from standard deviation and coefficient of variation.
5. When kinetic method by Szasz (X axis) is compared with the colorimetric method by Dada Company Y axis), correlation between them is very good showing a coefficient of correlation (=0.994. y=0.871x+1.5), and GGT values by colorimetric method are lower
6. In the samples with lower GGT activity, the reaction rate is pararell to the reaction time, but in those with higher activity the former falls with the latter. The method by Szasz measures the initial reaction rate, so it is very reasonable.
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