Murray D L, Rathbun W B
Ophthalmology Department, University of Minnesota, Minneapolis 55455.
Curr Eye Res. 1990 Jan;9(1):55-63. doi: 10.3109/02713689009000055.
This investigation was concerned with factors which would maximize and inhibit L-cyst(e)ine uptake and glutathione synthesis of rat lenses cultured for 24 hours in a medium containing [35S]-L-cystine. The lenticular protein-free extract was separated and quantified by use of HPLC equipment which included an in-line radioisotope detector coupled with extensive post-run computer analysis. Six thiols were assessed for their ability to increase the uptake of L-cyst(e)ine and its utilization for glutathione synthesis. The most successful was 2-mercaptoethanol, which increased the L-cyst(e)ine uptake 3.6-fold and glutathione synthesis 2.9-fold. This work demonstrated that the rate of glutathione synthesis was directly proportional to the rate of uptake of L-cyst(e)ine. An inhibitor of glutathione synthesis, buthionine sulfoximine, in a concentration range of 0.11-3 mM, decreased uptake of the [35S]-label by one-third. The 3.0 mM concentration inhibited glutathione synthesis 98.7% and decreased glutathione 51% in 24 hours. The data indicate that half the glutathione disappeared in 23 hours in these cultured rat lenses. Because determination of this value did not depend upon the variable rate of cysteine transport, the value may approximate the in vivo value.
本研究关注的是在含有[35S]-L-胱氨酸的培养基中培养24小时的大鼠晶状体中，能使L-胱（半胱）氨酸摄取及谷胱甘肽合成最大化和受到抑制的因素。使用配备在线放射性同位素检测器并结合广泛的运行后计算机分析的高效液相色谱设备，对无晶状体蛋白提取物进行分离和定量。评估了六种硫醇增加L-胱（半胱）氨酸摄取及其用于谷胱甘肽合成的能力。最有效的是2-巯基乙醇，它使L-胱（半胱）氨酸摄取增加了3.6倍，谷胱甘肽合成增加了2.9倍。这项工作表明，谷胱甘肽合成速率与L-胱（半胱）氨酸摄取速率成正比。谷胱甘肽合成抑制剂丁硫氨酸亚砜胺在0.11 - 3 mM的浓度范围内，使[35S]标记的摄取减少了三分之一。3.0 mM的浓度在24小时内抑制谷胱甘肽合成98.7%，并使谷胱甘肽减少51%。数据表明，在这些培养的大鼠晶状体中，一半的谷胱甘肽在23小时内消失。由于该值的测定不依赖于半胱氨酸运输的可变速率，该值可能接近体内值。
