Saxena A K, Saxena P, Wu X, Obrenovich M, Weiss M F, Monnier V M
Case Western Reserve University School of Medicine, Cleveland, Ohio, 44106, USA.
Biochem Biophys Res Commun. 1999 Jul 5;260(2):332-8. doi: 10.1006/bbrc.1999.0898.
Aging and age-related diseases are associated with the production of reactive oxygen species which modify lipids, proteins and DNA. Here we hypothesized the glyco- and lipoxidation product N(epsilon)-(carboxymethyl)lysine (CML) in proteins should bind divalent and redox active transition metal binding. CML-rich poly-L-lysine and bovine serum albumin (BSA) were chemically prepared and found to bind non-dialyzable Cu(2+), Zn(2+) and Ca(2+). CML-BSA-copper complexes oxidized ascorbate and depolymerized protein in the presence of H(2)O(2). CML-rich tail tendons implanted for 25 days into the peritoneal cavity of diabetic rats had a 150% increase in copper content and oxidized ascorbate three times faster than controls. CML-rich proteins immunoprecipitated from serum of uremic patients oxidized four times more ascorbate than control and generated spin adducts of DMPO in the presence of H(2)O(2). The chelator DTPA suppressed ascorbate oxidation thereby implicating transition metals in the process. In aging and disease, CML accumulation may result in a deleterious vicious cycle since CML formation itself is catalyzed by lipoxidation and glycoxidation.
衰老及与年龄相关的疾病与活性氧的产生有关，活性氧会改变脂质、蛋白质和DNA。在此，我们推测蛋白质中的糖氧化和脂质氧化产物N-ε-（羧甲基）赖氨酸（CML）应结合二价且具有氧化还原活性的过渡金属。我们通过化学方法制备了富含CML的聚-L-赖氨酸和牛血清白蛋白（BSA），发现它们能结合不可透析的Cu(2+)、Zn(2+)和Ca(2+)。在H(2)O(2)存在的情况下，CML-BSA-铜复合物会氧化抗坏血酸并使蛋白质解聚。将富含CML的尾腱植入糖尿病大鼠腹腔25天后，其铜含量增加了150%，氧化抗坏血酸的速度比对照组快三倍。从尿毒症患者血清中免疫沉淀出的富含CML的蛋白质氧化抗坏血酸的速度比对照组快四倍，并且在H(2)O(2)存在的情况下会生成DMPO的自旋加合物。螯合剂二乙烯三胺五乙酸（DTPA）抑制了抗坏血酸的氧化，从而表明过渡金属参与了这一过程。在衰老和疾病过程中，CML的积累可能会导致有害的恶性循环，因为CML的形成本身就是由脂质氧化和糖氧化催化的。
