作者:Feng-Xin Yin、风新 尹、Feng-Shan Wang、凤山 王、Ju-Zheng Sheng、举正 生
DOI:10.1074/jbc.c115.708396
日期:2016.2
structurally defined oligosaccharides were synthesized using a chemoenzymatic approach and subsequently cleaved using ChnAC. The degradation products resulting from this process were determined by mass spectrometry. The results revealed that ChnAC cleaved the β1,4-glycosidic linkages between glucuronic acid and glucosamine units when these bonds were located on the reducing end of the oligosaccharide. In contrast
糖胺聚糖(GAGs)是在许多生物过程中起着至关重要的功能作用的多糖,并且属于这一类的化合物已经涉及多种疾病。软骨素AC裂解酶(ChnAC)(EC 4.2.2.5)催化各种GAG的降解,包括硫酸软骨素和透明质酸,从而在其非还原端含相应的二糖,其中含有Δ(4)-不饱和糖醛酸。ChnAC已从各种细菌中分离出来,并用作研究和评估GAG测序的酶促工具。尽管其底物特异性和其晶体结构已被高分辨率确定的事实,ChnAC催化寡糖裂解的方向仍然不清楚。在此处,我们已经使用模型底物和重组ChnAC蛋白确定了底物解聚的结构线索和ChnAC的切割方向。使用化学酶学方法合成了几种结构确定的寡糖,随后使用ChnAC进行了切割。通过质谱法确定由该过程产生的降解产物。结果表明,当这些键位于寡糖的还原端时,ChnAC裂解了葡萄糖醛酸和葡糖胺单元之间的β1,4-糖苷键。相反,在寡糖的还原端存在GlcNAc-α-1,4-GlcA