Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases and College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu 215021, China.
Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, 110 8th St., Troy, NY, 12180, USA.
Carbohydr Polym. 2017 Feb 20;158:85-92. doi: 10.1016/j.carbpol.2016.12.010. Epub 2016 Dec 6.
Hyaluronic acid (HA), a glycosaminoglycan, is a linear polysaccharide with negative charge, composed of a repeating disaccharide unit [→4)-β-d-glucopyranosyluronic acid (1→3)-β-d- N-acetyl-d-glucoaminopyranose (1→] ([→4) GlcA (1→3) GlcNAc 1→]). It is widely used in different applications based on its physicochemical properties associated with its molecular weight. Enzymatic digestion by polysaccharides lyases is one of the most important ways to decrease the molecular weight of HA. Thus, it is important to understand the action patterns of lyases acting on HA. In this study, the action patterns of two common lyases, Flavobacterial chondroitinase AC I and Streptomyces hyaluronidase, were investigated by analyzing HA oligosaccharide digestion products. HA oligosaccharides having an odd-number of saccharide residues were observed in the products of both lyases, but their distributions were quite different. Chondroitinase AC acted more efficiently at the β 1-4 glycosidic bond linking GlcNAc and GlcA. Oligosaccharides, having an even number of saccharide residues, and with an unsaturated uronic acid (4-deoxy-α-l-threo-hex-4-enepyranosyluronic acid, △UA) residue at their non-reducing end represent the major product. A minor amount of oligosaccharides having an odd number of saccharide residues resulted from the irregular terminal residues of HA substrate chains. Hyaluronidase showed a more complicated product mixture. Its minimum recognition and digestion domain is HA heptasaccharide and it could cleave both β 1-4 and β 1-3 glycosidic linkages. The HA oligosaccharides, generated with a 2-acetamido-2,3-di-deoxy-β-d-erythro-hex-2-enopyranose (△HexNAc) at the non-reducing end, are believed to be unstable and undergo breakdown immediately after their generation, and the oligosaccharides with △UA residue at the non-reducing end are formed. Thus, oligosaccharides having both an even and odd-number saccharide residues with a △UA residue at their non-reducing ends, represent the major products of hyaluronidase acting on HA.
透明质酸（HA）是一种带负电荷的糖胺聚糖，由重复的二糖单元[→4）-β-d-葡萄糖醛酸（1→3）-β-d-N-乙酰-d-葡萄糖胺吡喃糖（1→]（[→4）GlcA（1→3）GlcNAc 1→）组成。它因其分子量相关的理化性质而广泛应用于不同的领域。多糖裂解酶的酶解是降低 HA 分子量的最重要方法之一。因此，了解作用于 HA 的裂解酶的作用模式非常重要。在这项研究中，通过分析 HA 寡糖的消化产物，研究了两种常见裂解酶Flavobacterial 软骨素酶 AC I 和 Streptomyces 透明质酸酶的作用模式。两种酶的产物中均观察到奇数糖残基数的 HA 寡糖，但分布差异很大。软骨素酶 AC 在连接 GlcNAc 和 GlcA 的β1-4 糖苷键上的作用效率更高。具有偶数糖残基数且非还原端具有不饱和糖醛酸（4-脱氧-α-l-苏型-己-4-烯吡喃糖醛酸，△UA）残基的寡糖是主要产物。HA 底物链末端不规则的寡糖数量较少。透明质酸酶表现出更复杂的产物混合物。它的最小识别和消化域是 HA 七糖，可以切割β1-4 和β1-3 糖苷键。非还原端带有 2-乙酰氨基-2,3-二脱氧-β-d-赤型-己-2-烯吡喃糖（△HexNAc）的 HA 寡糖被认为是不稳定的，并且在生成后立即分解，形成非还原端带有△UA 残基的寡糖。因此，非还原端带有△UA 残基的具有偶数和奇数糖残基数的寡糖是透明质酸酶作用于 HA 的主要产物。
