ANTIOXIDANT POTENTIAL OF HOMOCYSTAMIDE LDL ADDUCT

同型半胱氨酸硫内酯是一种环状硫酯， 在动脉粥样硬化形成中。 该分子将容易地酰化伯胺， 形成高结晶酰胺加合物，其含有伯胺和 硫醇 在这里，我们对抗氧化剂进行了表征和评价， 同型半胱氨酸-低密度脂蛋白（LDL）加合物的潜力， 高半胱氨酸硫代内酯与 低密度脂蛋白 用同型半胱氨酸硫代内酯处理低密度脂蛋白， LDL结合巯基含量的时间依赖性增加， 在75分钟时约250 nmol巯基/mg LDL蛋白。 的 LDL巯基含量增加后，LDL聚集， 75分钟 LDL结合巯基的增加是可逆的， 用硫醇阻断自旋标记物甲硫基磺酸盐处理。 通过电子自旋共振（ESR）自旋标记评估 技术，同型半胱氨酸加合物主要暴露于 低密度脂蛋白的水相，显示了尖锐的ESR谱，大大 用顺磁性弛豫剂铬增宽 草酸盐。 的相对电泳迁移率 同型半胱氨酸-LDL加合物相对于天然LDL增加。 高半胱氨酸硫代内酯处理的伯氨基浓度 LDL与天然LDL无显著差异（p < 0.05）。 的 同型半胱氨酸-LDL加合物对Cu（2+）-和2，2 '-偶氮双具有抗性 （2-脒基丙烷）介导的氧化（相对于天然LDL）， 通过硫代巴比妥反应性物质的形成来测量， 维生素E的消耗用N-乙基马来酰胺封闭硫醇 阻止了同型半胱氨酸-LDL加合物的抗氧化作用。 的 同型半胱氨酸-LDL加合物与 动脉粥样硬化的发展进行了讨论。

Homocysteine thiolactone is a cyclic thioester that is implicated in atherogenesis. This molecule will readily acylate primary amines, forming a homocystamide adduct, which contains a primary amine and a thiol. Here, we have characterized and evaluated the antioxidant potential of the homocystamide-low-density lipoprotein (LDL) adduct, a product of the acylation reaction between homocysteine thiolactone and LDL. Treatment of LDL with homocysteine thiolactone resulted in a time-dependent increase in LDL-bound thiol content that reached approximately 250 nmol thiol/mg LDL protein at 75 minutes. The increase in LDL thiol content was followed by aggregation of LDL after 75 minutes. The increase in LDL-bound thiols was reversible by treatment with the thiol blockersing spin label, methanethiosulfonate. As assessed by the electron spin resonance (ESR) spin labeling technique, the homocystamide adducts were predominately exposed to the aqueous phase of LDL, shown by the sharp ESR spectra that were greatly broadened by the hydrophillic paramagnetic relaxing agent, chromium oxalate. The relative electrophoretic mobility of the homocystamide-LDL adduct was increased with respect to native LDL. Primary amino group concentration of homocysteine thiolactone-treated LDL was not significantly different than native LDL (p < 0.05). The homocystamide-LDL adduct was resistant to Cu(2+)- and 2,2'-azobis (2-amidinopropane)- mediated oxidation (with respect to native LDL) as measured by the formation of thiobarbituric reactive substances and the depletion of vitamin E. Blocking thiols with N-ethylmaleamide prevented the antioxidant effect of the homocystamide-LDL adduct. The potential relationship between the homocystamide-LDL adduct and the development of atherosclerosis is discussed.