Malloy M H, Rassin D K, McGanity W J
Biol Neonate. 1983;44(1):1-9. doi: 10.1159/000241688.
In order to investigate the mechanisms by which cyst(e)ine (referring in the following to the mixture, in any proportion, of the sulfhydryl form of this compound - cysteine - and the disulfide form - cystine) transfer across the placenta to the fetus might be limited we first assessed the original observation that cyst(e)ine concentrations in fetal plasma are less than or equal to maternal cyst(e)ine concentrations. Second, we determined the capacity of the placenta to concentrate cyst(e)ine. And third, using an animal model, we determined the effects of providing excess cysteine to maternal rats on maternal-fetal cyst(e)ine transfer. Our data confirm (1) that cyst(e)ine is present in concentrations in human cord plasma that are equal to maternal plasma cyst(e)ine concentrations; (2) establish that cyst(e)ine is concentrated in the placenta, and (3) suggest that the incorporation of cyst(e)ine into glutathione in the placenta may limit the transfer of cyst(e)ine to the fetus.
为了研究半胱氨酸（以下指该化合物的巯基形式——半胱氨酸和二硫形式——胱氨酸以任何比例混合）跨胎盘向胎儿转运可能受限的机制，我们首先评估了最初的观察结果，即胎儿血浆中的半胱氨酸浓度小于或等于母体半胱氨酸浓度。其次，我们测定了胎盘浓缩半胱氨酸的能力。第三，使用动物模型，我们测定了给孕鼠提供过量半胱氨酸对母胎半胱氨酸转运的影响。我们的数据证实：（1）人脐血血浆中半胱氨酸的浓度与母体血浆半胱氨酸浓度相等；（2）证实半胱氨酸在胎盘中被浓缩，并且（3）表明胎盘中半胱氨酸掺入谷胱甘肽可能会限制半胱氨酸向胎儿的转运。
