Research Institute, The Hospital for Sick Children, Ontario, Canada.
Pediatr Res. 2010 Mar;67(3):320-4. doi: 10.1203/PDR.0b013e3181ca036f.
Controversy exists as to whether the parenterally (PN) fed human neonate is capable of synthesizing adequate cysteine from methionine if the total dietary requirement for sulfur amino acid (SAA) is provided as methionine only. The goal of this study was to gather data on whether glutathione (GSH) synthesis is maximized at a methionine intake previously shown to be adequate for protein synthesis in the PN-fed human neonate. We measured GSH concentration, fractional, and absolute synthesis rate in five PN-fed human neonates. Each neonate underwent two isotope infusion studies of 7 h duration after a 2-d adaptation to the total SAA requirement (methionine only) and again after a further 2-d adaptation to the same methionine intake supplemented with cysteine at 10 mg x kg(-1) x d(-1). Cysteine supplementation did not significantly affect GSH synthesis. These data suggest that term infants are capable of synthesizing cysteine from methionine, not only for protein but also for GSH synthesis.
关于在仅提供蛋氨酸作为全部硫氨基酸（SAA）饮食需求的情况下，肠外（PN）喂养的人类新生儿是否能够从蛋氨酸合成足够的半胱氨酸，存在争议。本研究的目的是收集数据，以了解在先前已证明足以满足 PN 喂养的人类新生儿蛋白质合成的蛋氨酸摄入量下，谷胱甘肽（GSH）合成是否最大化。我们测量了五个 PN 喂养的人类新生儿的 GSH 浓度、分数和绝对合成率。每个新生儿在适应全部 SAA 需求（仅蛋氨酸）2 天后和再适应 2 天后，进行了两次持续 7 小时的同位素输注研究，在此期间，蛋氨酸摄入量相同，但补充了 10mg/kg/d 的半胱氨酸。半胱氨酸补充并未显著影响 GSH 合成。这些数据表明，足月婴儿不仅能够从蛋氨酸合成半胱氨酸用于蛋白质合成，也能够用于 GSH 合成。
