Plaas A H, West L A, Wong-Palms S, Nelson F R
Shriners Hospital for Children, Tampa Unit, Tampa, Florida 33612, USA.
J Biol Chem. 1998 May 15;273(20):12642-9. doi: 10.1074/jbc.273.20.12642.
Chondroitin lyase products of aggrecan and small proteoglycans from normal and osteoarthritic cartilages were analyzed for chain internal Deltadisaccharides and terminal mono- or disaccharides. Chondroitin and dermatan sulfate chains from arthritic cartilages were of essentially normal size and internal sulfation but had significantly altered sulfation of the terminal residues. Whereas in normal cartilage, approximately 60% of terminal GalNAc4S was 4, 6-disulfated, it was reduced to approximately 30% in osteoarthritic cartilage. This is most likely due to a lower terminal GalNAc4, 6S-disulfotransferase activity and reveals that metabolic changes in osteoarthritis can affect this distinct sulfation step during chondroitin and dermatan sulfate synthesis. GlcAbeta1,3GalNAc6S-, the mimotope for antibody 3B3(-), was present on approximately 8 and approximately 10% of chains from normal and osteoarthritic cartilages, respectively. 3B3(-) assayed by immunodot blot was within the normal range for most osteoarthritic samples, with only 5 of 24 displaying elevated reactivity. This resulted not from a higher content of mimotope, but possibly from other structural changes in the proteoglycan that increase mimotope reactivity. In summary, chemical determination of sulfation isomers at the non-reducing termini of chondroitin and dermatan sulfate provides a reliable assay for monitoring proteoglycan metabolism not only during normal growth of cartilage but also during remodeling of cartilage in osteoarthritis.
分析了来自正常和骨关节炎软骨的聚集蛋白聚糖和小蛋白聚糖的软骨素裂解酶产物的链内Δ二糖以及末端单糖或二糖。来自骨关节炎软骨的软骨素和硫酸皮肤素链在大小和内部硫酸化程度上基本正常，但末端残基的硫酸化有显著改变。在正常软骨中，约60%的末端GalNAc4S是4,6-二硫酸化的，而在骨关节炎软骨中这一比例降至约30%。这很可能是由于末端GalNAc4,6S-二硫酸转移酶活性较低，表明骨关节炎中的代谢变化会影响软骨素和硫酸皮肤素合成过程中这一独特的硫酸化步骤。GlcAbeta1,3GalNAc6S-，即抗体3B3(-)的模拟表位，分别存在于来自正常和骨关节炎软骨的约8%和约10%的链上。通过免疫斑点印迹法检测，大多数骨关节炎样本中的3B3(-)在正常范围内，24个样本中只有5个显示反应性升高。这并非源于模拟表位含量更高，而是可能源于蛋白聚糖的其他结构变化增加了模拟表位的反应性。总之，对软骨素和硫酸皮肤素非还原末端硫酸化异构体的化学测定为监测蛋白聚糖代谢提供了一种可靠的检测方法，不仅可用于监测软骨正常生长过程中的情况，还可用于监测骨关节炎中软骨重塑过程中的情况。
