Pallardo F V, Sastre J, Asensi M, Rodrigo F, Estrela J M, Viña J
Departamento de Fisiología, Facultad de Medicina, Universidad de Valencia, Spain.
Biochem J. 1991 Mar 15;274 ( Pt 3)(Pt 3):891-3. doi: 10.1042/bj2740891.
Glutathione metabolism was studied in isolated hepatocytes from foetal, newborn and adult rats. The GSH/GSSG ratio decreased 15-20-fold through the foetal-neonatal-adult transition. This was mainly due to an increase in GSSG. All enzyme activities involved in the glutathione redox cycle tend to increase during that transition, but the relative increases in glutathione peroxidase and glutathione S-transferase were 3-5 times those of glutathione reductase or glucose-6-phosphate dehydrogenase. GSH synthesis from methionine as a sulphur source was 6 times lower in foetal than in adult hepatocytes. However, when N-acetylcysteine was used as a sulphur donor to by-pass the cystathionine pathway, the rates of GSH synthesis were similar in foetal and adult cells. This is due to the fact that cystathionase activity in foetal cells is very low. This low activity is reflected in the blood amino acid pattern, where the concentration of cysteine rises from 8 to 52 microM from foetuses to adult rats. This supports the idea that cysteine may be an essential amino acid for the premature animal.
在来自胎儿、新生和成年大鼠的分离肝细胞中研究了谷胱甘肽代谢。通过胎儿-新生儿-成年的转变，谷胱甘肽（GSH）/氧化型谷胱甘肽（GSSG）比值下降了15至20倍。这主要是由于GSSG增加所致。在该转变过程中，谷胱甘肽氧化还原循环中涉及的所有酶活性都趋于增加，但谷胱甘肽过氧化物酶和谷胱甘肽S-转移酶的相对增加幅度是谷胱甘肽还原酶或葡萄糖-6-磷酸脱氢酶的3至5倍。以蛋氨酸作为硫源的GSH合成在胎儿肝细胞中比在成年肝细胞中低6倍。然而，当使用N-乙酰半胱氨酸作为硫供体绕过胱硫醚途径时，胎儿和成年细胞中的GSH合成速率相似。这是因为胎儿细胞中的胱硫醚酶活性非常低。这种低活性反映在血液氨基酸模式中，从胎儿到成年大鼠，半胱氨酸的浓度从8微摩尔/升升至52微摩尔/升。这支持了半胱氨酸可能是早产动物必需氨基酸的观点。
