Université Paris-Saclay, Univ Evry, CNRS, LAMBE, 91025 Evry-Courcouronnes, France.
SOLEIL, l'Orme des Merisiers, St Aubin, BP48, 91192 Gif sur Yvette Cedex, France.
Glycobiology. 2021 Aug 7;31(7):751-761. doi: 10.1093/glycob/cwab004.
Mammalian hyaluronidases are endo-N-acetyl-D-hexosaminidases involved in the catabolism of hyaluronic acid (HA) but their role in the catabolism of chondroitin sulfate (CS) is also examined. HA and CS are glycosaminoglycans implicated in several physiological and pathological processes, and understanding their metabolism is of significant importance. Data have been previously reported on the degradation of CS under the action of hyaluronidase, yet a detailed structural investigation of CS depolymerization products remains necessary to improve our knowledge of the CS depolymerizing activity of hyaluronidase. For that purpose, the fine structural characterization of CS oligosaccharides formed upon the enzymatic depolymerization of various CS subtypes by hyaluronidase has been carried out by high-resolution Orbitrap mass spectrometry (MS) and extreme UV (XUV) photodissociation tandem MS. The exact mass measurements show the formation of wide size range of even oligosaccharides upon digestion of CS-A and CS-C comprising hexa- and octa-saccharides among the main digestion products, as well as formation of small quantities of odd-numbered oligosaccharides, while no hyaluronidase activity was detected on CS-B. In addition, slight differences have been observed in the distribution of oligosaccharides in the digestion mixture of CS-A and CS-C, the contribution of longer oligosaccharides being significantly higher for CS-C. The sequence of CS oligosaccharide products determined XUV photodissociation experiments verifies the selective β(1 → 4) glycosidic bond cleavage catalyzed by mammal hyaluronidase. The ability of the mammal hyaluronidase to produce hexa- and higher oligosaccharides supports its role in the catabolism of CS anchored to membrane proteoglycans and in extra-cellular matrix.
哺乳动物透明质酸酶属于内切-N-乙酰-D-氨基己糖苷酶，参与透明质酸 (HA) 的分解代谢，但也研究了其在硫酸软骨素 (CS) 分解代谢中的作用。HA 和 CS 是糖胺聚糖，涉及多种生理和病理过程，了解它们的代谢具有重要意义。先前已经报道了透明质酸酶作用下 CS 的降解数据，但仍需要对 CS 解聚产物进行详细的结构研究，以提高我们对透明质酸酶分解 CS 活性的认识。为此，通过高分辨率轨道阱质谱 (MS) 和极紫外 (XUV) 光解串联 MS 对透明质酸酶酶解各种 CS 亚型后形成的 CS 寡糖进行了精细结构表征。精确质量测量表明，在 CS-A 和 CS-C 的消化过程中形成了广泛的大小范围的偶数寡糖，包括主要消化产物中的六糖和八糖，以及少量奇数寡糖的形成，而 CS-B 则没有检测到透明质酸酶活性。此外，在 CS-A 和 CS-C 的消化混合物中观察到寡糖的分布存在细微差异，CS-C 中较长寡糖的贡献明显更高。XUV 光解实验确定的 CS 寡糖产物序列验证了哺乳动物透明质酸酶催化的选择性β(1→4)糖苷键裂解。哺乳动物透明质酸酶产生六糖和更高寡糖的能力支持其在与膜蛋白聚糖和细胞外基质结合的 CS 分解代谢中的作用。
