Ramakrishnan S, Sulochana K N
Department of Biochemistry, Vision Research Foundation, Madras, India.
Exp Eye Res. 1993 Nov;57(5):623-8. doi: 10.1006/exer.1993.1167.
The amino acid lysine has been reported to delay cataractogenesis by 'some unknown mechanism'. Lysine and glycine were found to react with glucose at physiological pH and temperature and undergo non-enzymic glycation. The formation of glycated lysine was shown by paper and thin-layer chromatography, HPLC and using an authentic sample of epsilon-fructosyl lysine. Confirmation was made by studies on incorporation of U-[14C]glucose into lysine and glycine. The extent of glycation of lysine was 15.5% in 96 hr and rose to 20% in 20 days. Lysine and glycine alone of varying concentrations lowered the extent of glycation of lens proteins significantly in glucose-treated homogenates of normal lens from humans and goats. Scavenging of intracellular glucose and thereby protecting the lens proteins from excessive glycation appears to be the mechanism of action by which lysine and glycine could exercise beneficial effect on cataract.
据报道，氨基酸赖氨酸通过“某种未知机制”延缓白内障的形成。研究发现，赖氨酸和甘氨酸在生理pH值和温度下会与葡萄糖发生反应，并进行非酶糖基化。通过纸层析、薄层层析、高效液相色谱法以及使用ε-果糖基赖氨酸的标准样品，证实了糖化赖氨酸的形成。通过研究U-[14C]葡萄糖掺入赖氨酸和甘氨酸的情况进行了确认。赖氨酸的糖基化程度在96小时内为15.5%，在20天内升至20%。在葡萄糖处理的人及山羊正常晶状体匀浆中，不同浓度的赖氨酸和甘氨酸单独使用可显著降低晶状体蛋白的糖基化程度。清除细胞内葡萄糖，从而保护晶状体蛋白免受过度糖基化，似乎是赖氨酸和甘氨酸对白内障产生有益作用的作用机制。
