Sulochana Konerirajapuram N, Ramprasad Srinivasan, Coral Karnuakaran, Lakshmi Soundarajan, Punitham Ranganathan, Narayanasamy Angayarkanni, Ramakrishnan Sivaramakrishna
Biochemistry Research Department, Vision Research Foundation, Sankara Nethralaya, Chennai, India.
Med Sci Monit. 2003 Jun;9(6):BR220-4.
Structural and functional impairment in vitreous collagen plays an important role in the pathogenesis of diabetic retinopathy. Collagen being a long-lived protein is prone to both glycation and glycoxidation, resulting in accumulation of advanced glycation end products (AGE). The objective of our study was to explore the extent of glycation by glucose, and iron- and copper-mediated glycoxidation of human vitreous collagen, and also to study the beneficial effects of lysine, inositol and aminoguanidine as antiglycating and anti-cross linking agents.
MATERIAL/METHODS: Vitreous from human donor eyeballs was pooled and collagen was extracted using 0.9 M NaCl. Collagen was estimated by measuring the hydroxyproline content. The extracted collagen was used for glycation and glycoxidation studies. Glycation studies were conducted using U14C glucose, along with anti-glycating agents, such as lysine and aminoguanidine. Metal-mediated glycoxidation studies were done by measuring collagen content in cyanogen bromide insoluble fraction, in the presence and absence of an anti-cross linking agent, inositol.
Human vitreous collagen extractable with 0.9 M NaCl was glycated by glucose at 5 and 10 mM concentrations under physiological conditions of temperature and pH. An anti-glycating effect was exhibited by lysine, inositol and aminoguanidine, of which lysine was the best (76% antiglycating activity) followed by inositol. Inositol was also found to be useful in inhibiting glycoxidation.
Vitreous collagen undergoes glycation, as well as iron- and copper-mediated glycoxidation, leading to possible structural and functional impairment. Glycation and glycoxidation are inhibited, significantly by lysine and inositol respectively.
玻璃体胶原蛋白的结构和功能损伤在糖尿病视网膜病变的发病机制中起重要作用。胶原蛋白作为一种长寿蛋白，容易发生糖基化和糖氧化反应，导致晚期糖基化终产物（AGE）的积累。我们研究的目的是探讨葡萄糖对人玻璃体胶原蛋白的糖基化程度，以及铁和铜介导的糖氧化程度，并研究赖氨酸、肌醇和氨基胍作为抗糖基化和抗交联剂的有益作用。
材料/方法：收集人供体眼球的玻璃体，用0.9M氯化钠提取胶原蛋白。通过测量羟脯氨酸含量来估计胶原蛋白。提取的胶原蛋白用于糖基化和糖氧化研究。使用14C葡萄糖以及抗糖基化剂（如赖氨酸和氨基胍）进行糖基化研究。在有和没有抗交联剂肌醇的情况下，通过测量溴化氰不溶部分中的胶原蛋白含量来进行金属介导的糖氧化研究。
在温度和pH的生理条件下，0.9M氯化钠可提取的人玻璃体胶原蛋白在5mM和10mM浓度的葡萄糖作用下发生糖基化。赖氨酸、肌醇和氨基胍表现出抗糖基化作用，其中赖氨酸效果最佳（抗糖基化活性为76%），其次是肌醇。还发现肌醇可用于抑制糖氧化。
玻璃体胶原蛋白会发生糖基化以及铁和铜介导的糖氧化，导致可能的结构和功能损伤。赖氨酸和肌醇分别显著抑制糖基化和糖氧化。
