Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Sofia.
Glycoconj J. 2011 Aug;28(6):385-95. doi: 10.1007/s10719-011-9337-2. Epub 2011 Jun 10.
The oligosaccharide structures of the structural subunit HtH1 of Haliotis tuberculata hemocyanin (HtH) were studied by mass spectral sequence analysis of the glycans. The proposed structures are based on MALDI-TOF-MS data before and after treatment with the specific exoglycosidases β1-3,4,6-galactosidase and α1-6(>2,3,4) fucosidase followed by sequence analysis via electrospray ionization MS/MS-spectra. In total, 15 glycans were identified as a highly heterogeneous group of structures. As in most molluscan hemocyanins, the glycans of HtH1 contain a terminal MeHex, but more interestingly, a novel structural motif was observed: MeHex[Fuc(α1-3)-]GlcNAc, including thus MeHex and (α1-3)-Fuc residues being linked to an internal GlcNAc residue. While the functional unit (FU) c (HtH1-c) is completely lacking any potential glycosylation site, FU-h possesses a second exposed sugar attachment site between beta-strands 8 and 9 within the beta sandwich domain compared to the other FUs. The glycosylation pattern/sites show a high degree of conservation. In FU-h two prominent potential glycosylation sites can be detected. The finding that HtH1 is not able to form multidecameric structures in vivo could be explained by the presence of the exposed glycan on the surface of FU-h.
采用 MALDI-TOF-MS 对特定外切糖苷酶β1-3,4,6-半乳糖苷酶和α1-6(>2,3,4)岩藻糖苷酶处理前后的糖肽进行序列分析，研究了鲍血细胞色素 HtH1 结构亚基 HtH1 的寡糖结构。这些结构是基于 MALDI-TOF-MS 数据提出的，在经过特定外切糖苷酶β1-3,4,6-半乳糖苷酶和α1-6(>2,3,4)岩藻糖苷酶处理后，再通过电喷雾电离 MS/MS 谱进行序列分析。总共鉴定出 15 种聚糖，它们是一组高度异质的结构。与大多数软体动物血蓝蛋白一样，HtH1 的聚糖含有末端 MeHex，但更有趣的是，观察到了一个新的结构基序：MeHex[Fuc(α1-3)-]GlcNAc，其中包括 MeHex 和（α1-3）-Fuc 残基与内部 GlcNAc 残基相连。虽然功能单元（FU）c（HtH1-c）完全没有任何潜在的糖基化位点，但与其他 FUs 相比，FU-h 在β三明治结构域的β链 8 和 9 之间存在第二个暴露的糖附着位点。糖基化模式/位点具有高度的保守性。在 FU-h 中可以检测到两个突出的潜在糖基化位点。由于 FU-h 表面存在暴露的聚糖，HtH1 无法在体内形成多聚体结构，这一发现可以得到解释。
