Rollins D, Larsson A, Steen B, Krishnaswamy K, Hagenfeldt L, Moldéus P, Rane A
J Pharmacol Exp Ther. 1981 Jun;217(3):697-700.
Human fetal and adult liver were found to have similar concentrations of acid soluble sulfhydryl (SH) groups (7.4 mmol/kg) in the same range as is found in adult mouse and rat liver. The concentration was 4-fold higher than in human fetal adrenal gland tissue. Methods specific for glutathione (GSH) associated SH groups revealed that the postmortem levels of GSH is very low (0.4 mmol/kg) in relation to total SH groups. In contrast, the levels of cysteine were high (2.8 mmol/kg), indicating a rapid cleavage of GSH. Only negligible amounts of gamma-glutamylcysteine and cysteinylglycine were measured. Our findings may be explained by high fetal activity of gamma-glutamyl transpeptidase (which metabolizes GSH) that has been documented previously both in man and in experimental animals. High activities of the two GSH-synthesizing enzymes, gamma-glutamylcysteine synthetase and GSH synthetase were found in the human fetal liver (7.1 and 3.0 mukat/kg, respectively). The activities of these enzymes were in the same range as in human adult liver, whereas that of gamma-glutamyl transpeptidase was 3-fold higher in the fetal liver. Our results demonstrate the presence of high concentration of SH groups and capacity to synthesize GSH already in the first and second trimester of the human fetal gestation. This has more than theoretical interest, since we assume that the SH groups (GSH) have importance for the protection of the fetus against drugs and foreign compounds and their (toxic) metabolites, the formation of which is catalyzed by the fetus itself.
研究发现，人类胎儿肝脏和成人肝脏中酸溶性巯基（SH）的浓度相似（7.4 mmol/kg），与成年小鼠和大鼠肝脏中的浓度处于同一范围。该浓度比人类胎儿肾上腺组织中的浓度高4倍。针对与谷胱甘肽（GSH）相关的SH基团的特异性方法显示，相对于总SH基团而言，死后GSH的水平非常低（0.4 mmol/kg）。相反，半胱氨酸的水平较高（2.8 mmol/kg），表明GSH发生了快速裂解。仅检测到极少量的γ-谷氨酰半胱氨酸和半胱氨酰甘氨酸。我们的研究结果可能是由于先前在人类和实验动物中均已记录到的γ-谷氨酰转肽酶（可代谢GSH）在胎儿期具有较高活性。在人类胎儿肝脏中发现了两种GSH合成酶，即γ-谷氨酰半胱氨酸合成酶和GSH合成酶的活性较高（分别为7.1和3.0 mukat/kg）。这些酶的活性与人类成人肝脏中的活性处于同一范围，而γ-谷氨酰转肽酶的活性在胎儿肝脏中则高出3倍。我们的结果表明，在人类胎儿妊娠的头三个月和第二个月中就已经存在高浓度的SH基团以及合成GSH的能力。这不仅仅具有理论意义，因为我们认为SH基团（GSH）对于保护胎儿免受药物、外来化合物及其（有毒）代谢产物的影响具有重要作用，而这些物质的形成是由胎儿自身催化的。
