Hospital Universitário Clementino Fraga Filho, Laboratório de Tecido Conjuntivo, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
Instituto de Bioquímica Médica Leopoldo de Meis, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
Glycobiology. 2018 Aug 1;28(8):565-579. doi: 10.1093/glycob/cwy048.
Fucosylated chondroitin sulfates (FCSs) and sulfated fucans (SFs) are conspicuous components of the body wall of sea cucumbers (Holothuroidea). FCSs are composed of a central core of chondroitin sulfate (CS) decorated with branches of mono- or both mono- and disaccharides of α-fucose (FCS types I and II, respectively). FCSs type II have heterogeneous and irregularly distributed α-fucose branches; however, the novel FCS type II from Holothuria lentiginosa described herein via solution nuclear magnetic resonance has strikingly homogeneous α-fucose branches neatly distributed along its CS core. This FCS is built up of three distinct sequential units composed of the typical CS disaccharides of FCSs, rich in β-galactosamine-4,6diS, decorated with branches of α-Fucp-2,4diS, α-Fucp-3,4diS or α-Fucp[1→3]α-Fucp-4S[1→ linked to the position 3- of the β-glucuronic acid. Conformational analyses of these repetitive units revealed a fairly rigid structure despite of the high sulfate content of their α-fucose branches. We also determined the structure of the SF from H. lentiginosa as a repetitive tetrasaccharide sequence composed of →3]α-Fucp-2,4diS[1→3]α-Fucp[1→3]α-Fucp-2S[1→3]α-Fucp-2S[1→. Furthermore, we determined that the nonsulfated α-fucose units present in FCS type II did not interfere with their anticoagulant potencies and affinities to calcium. FCS is an autapomorphic molecular character of the class Holothuroidea and the composition of their α-fucose branches differs in a species-specific manner. Branches containing α-Fucp-2,4diS are the most common within the extant holothurians, being found in 90% of the FCSs characterized thus far.
岩栖海参（Holothuroidea）体壁的显著成分包括岩藻糖基硫酸软骨素（Fucosylated chondroitin sulfates，FCSs）和硫酸岩藻聚糖（sulfated fucans，SFs）。FCSs 由核心的硫酸软骨素（chondroitin sulfate，CS）组成，由单糖或单糖和二糖的 α-岩藻糖（FCS 类型 I 和 II，分别）分支修饰。FCSs 类型 II 具有不均匀和不规则分布的 α-岩藻糖分支；然而，本文通过溶液核磁共振描述的来自糙海参（Holothuria lentiginosa）的新型 FCS 类型 II 具有惊人的均匀 α-岩藻糖分支，整齐地分布在其 CS 核心上。该 FCS 由三个不同的连续单元组成，这些单元由 FCS 典型的 CS 二糖组成，富含β-半乳糖胺-4,6 二硫酸盐，由 α-Fucp-2,4 二硫酸盐、α-Fucp-3,4 二硫酸盐或α-Fucp[1→3]α-Fucp-4S[1→连接到β-葡萄糖醛酸的位置 3-。尽管这些 α-岩藻糖分支的硫酸盐含量较高，但对这些重复单元的构象分析表明其结构相当刚性。我们还确定了来自糙海参的 SF 的结构，它是由重复的四糖序列组成的，该序列由→3]α-Fucp-2,4 二硫酸盐[1→3]α-Fucp[1→3]α-Fucp-2S[1→3]α-Fucp-2S[1→组成。此外，我们确定 FCS 类型 II 中存在的非硫酸化 α-岩藻糖单元不会干扰其抗凝活性和与钙的亲和力。FCS 是类海参纲的特有分子特征，其 α-岩藻糖分支的组成在种间特异性方式上存在差异。含有 α-Fucp-2,4 二硫酸盐的分支是现存海参纲中最常见的分支，迄今为止已鉴定的 90%的 FCSs 中都存在这种分支。
