活性氧及过渡金属对关节软骨蛋白聚糖降解的影响

在温育的小牛关节软骨切片介质中加入黄嘌呤氧化酶/次黄嘌呤活性氧产生系统,可使关节软骨蛋白聚糖的降解显著增高。这种作用不能被超氧化物歧化酶或铁络合剂二乙三胺戊乙酸抑制,但可被过氧化氢酶抑制。在温育的介质中加入H_2O_2,也可使关节软骨蛋白聚糖降解增高,Cu~(2+)或Co~(2+)对此有显著促进作用,其它过渡金属则作用不明显。应用Sepharose 6B柱层析,分析软骨蛋白聚糖降解产物,多数实验组只在kD=0处有一个大分子的洗脱峰,但Cu~(2+)+H_2O_2组则在kD=0及0.57处出现两个洗脱峰(分别称为峰Ⅰ及峰Ⅱ)。醋酸纤维素薄膜双向电泳证实峰Ⅱ为硫酸软骨素,提示Cu~(2+)与H_2O_2复合物可导致蛋白聚糖分子的断裂。本研究结果可能有助于阐明某些变性型骨关节疾病的发病机理,例如因缺硒所致的大骨节病等。

Effects of Reactive Oxygen and Transition Metals on Degradation of Articular Cartilage Proteoglycan

When the articular cartilage slices of new born calf were incubated in the presence of xanthine oxidase and hypoxanthine, an oxygen radical generating system, the degradation of cartilage proteoglycan was increased significantly. This effect was not inhibited by superoxide dismutase or diethylenetriaminepentaacetic acid,but was inhibited by catalase. Addition of H2O2 to the incubation medium also enhanced the proteoglycan degradation of articular cartilage, and this effect was promoted significantly by Cu2+ or Co2+. Analyses of the degradation products of cartilage proteoglycan on Sepharose 6B chromatography showed one macromolecular peak at kD = 0 in many of the experimental groups, but there were two peaks at kD = 0 and 0.57(peak Ⅰ and peak Ⅱ respectively) in the H2O2 + Cu2+ group.Two-dimensional electrophoresis on cellulose acetate membrane confirmed that the peak Ⅱ was cho-ndroitin sulphate, it means that the complex of Cu2+ and H2O2 would lead to the breakage of proteoglycan molecules. These results might be helpful in understanding the pathogenesis of some degenerative joint diseases, such as Kashin-Beck disease related to selenium deficiency.