Goldberg D M, Martin J V
Digestion. 1975;12(4-6):232-46. doi: 10.1159/000197682.
The enzyme gamma-glutamyl transpeptidase is widely distributed throughout the body, notably kidney, seminal vesicles, pancreas, liver, spleen and brain. Being one of the enzymes of the gamma-glutamyl cycle, it is involved in aminoacid transport, catalysing a transpeptidation reaction between gamma-glutamyl peptides and most common amino acids. Methods of assay of the enzyme are based on its ability also to act on synthetic amides of glutamic acid; kinetic methods monitoring the release of p-nitroaniline from the substrate L-gamma-glutamyl p-nitroanilide are the most satisfactory. In diseases of the liver, the highest levels occur in association with cirrhosis, alcoholism, hepatic secondaries and cholestasis. As the enzyme is present in the endoplasmic reticulum of the hepatocyte, its activity is increased in situations leading to microsomal enzyme induction. Raised levels can also occur in pancreatitis, diabetes, myocardial infarction, congestive cardiac failure, chronic renal failure, cerebrovascular accidents, cerebral tumours and chronic obstructive pulmonary disease. Although the lack of specificity must be recognised, the estimation can be useful in the elucidation of some clearly defined problems arising during investigation of patients with suspected hepatic disease, especially where performed as part of a biochemical profile.
γ-谷氨酰转肽酶广泛分布于全身，尤其在肾脏、精囊、胰腺、肝脏、脾脏和大脑中。作为γ-谷氨酰循环的酶之一，它参与氨基酸转运，催化γ-谷氨酰肽与最常见氨基酸之间的转肽反应。该酶的测定方法基于其对谷氨酸合成酰胺也有作用的能力；监测底物L-γ-谷氨酰对硝基苯胺释放对硝基苯胺的动力学方法是最令人满意的。在肝脏疾病中，γ-谷氨酰转肽酶水平最高的情况与肝硬化、酒精中毒、肝转移瘤和胆汁淤积有关。由于该酶存在于肝细胞的内质网中，在导致微粒体酶诱导的情况下其活性会增加。γ-谷氨酰转肽酶水平升高也可发生在胰腺炎、糖尿病、心肌梗死、充血性心力衰竭、慢性肾衰竭、脑血管意外、脑肿瘤和慢性阻塞性肺疾病中。尽管必须认识到其缺乏特异性，但在阐明疑似肝脏疾病患者调查过程中出现的一些明确问题时，该酶的测定可能有用，特别是作为生化检查项目的一部分进行检测时。
