Dean R T, Roberts C R, Forni L G
Biosci Rep. 1984 Dec;4(12):1017-26. doi: 10.1007/BF01116694.
Bovine nasal cartilage slices, biosynthetically labelled in their proteoglycan with 35SO4, were used as substrate for the attack of free radicals generated on exposure to a Co60 source (which allows study of single radical species), and by chemical and enzymatic means. Systems generating hydroxyl (OH.) and superoxide (O2.-) radicals degraded the proteoglycan efficiently, while the hydroperoxy radical (HO2.) was less efficient; addition of appropriate radical scavengers inhibited degradation. The radioactive products were heterogeneous in molecular size, but with doses up to 3600 Gy were the same size range as intact chondroitin sulphate. The contained free amino groups, and more were liberated by aminopeptidase M digestion, implying that at least a small peptide was present. Thus a major site of radical attack may be the polypeptide chain. We suggest that free-radical fragmentation of polypeptides may be important both in extracellular catabolism and in intracellular proteolysis.
用35SO4对牛鼻软骨切片的蛋白聚糖进行生物合成标记，将其用作暴露于钴60源（可用于研究单个自由基种类）以及通过化学和酶促方法产生的自由基攻击的底物。产生羟基（OH.）和超氧阴离子（O2.-）自由基的系统能有效降解蛋白聚糖，而过氧羟基自由基（HO2.）的降解效率较低；添加适当的自由基清除剂可抑制降解。放射性产物的分子大小各异，但剂量高达3600 Gy时，其大小范围与完整的硫酸软骨素相同。其中所含的游离氨基，经氨肽酶M消化后会释放出更多，这意味着至少存在一个小肽段。因此，自由基攻击的一个主要位点可能是多肽链。我们认为，多肽的自由基断裂在细胞外分解代谢和细胞内蛋白水解中可能都很重要。
