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41.
Beck A Hillen N Dolashki A Stevanovic S Salvato B Voelter W Dolashka-Angelova P 《Biochimie》2007,89(8):938-949
In the present study the structures of two glycopeptides (G1 and G1'), isolated from FU RvH(1)-b and two glycopeptides (G2 and G3), isolated from the structural subunit RvH(1) of Rapana venosa hemocyanin, were determined. To structurally characterize the site-specific carbohydrate heterogeneity and binding site of the N-linked glycopeptide(s), a combination of capillary reversed-phase chromatography and ion trap mass spectrometry was used. The amino acid sequences of glycopeptides G1 and G1' determined by Edman degradation and MS/MS sequencing demonstrated that the oligosaccharides are linked to N-glycosylation sites. Two peptides (a glycosylated (G1) and non-glycosylated one) were identified in this fraction and no linkage sites were observed in the latter one. Based on the sequencing of the glycosylated fractions G1, G1', G2 and G3, the carbohydrate structure Man(alpha1-6)Man(alpha1-3)Man(beta1-4)GlcNAc(beta1-4)[Fuc(alpha1-6)]GlcNAc-R could be identified for glycopeptides G1 and G3, and only the typical core structure Man(alpha1-6)Man(alpha1-3)Man(beta1-4)GlcNAc(beta1-4)GlcNAc-R was found for G1' and G2. The Fuc residue found in glycopeptides G1 and G3 is attached to N-acetyl-glucosamine of the carbohydrate core, as often found in other glycoproteins. 相似文献
42.
Kaidong Zhang 《Carbohydrate research》2010,345(9):1114-1122
The synthesis of tetrapeptide-based β-turn mimetics containing spirocyclic glucose-templated 3-hydroxyproline hybrids Glc3′(S)-5′(R)(CH2OH)HypH and Glc3′(S)-5′(S)(CH2OH)HypH as proline mimetics is presented. NMR-based conformational analysis of Ac-Leu-d-Phe-[Glc3′(S)-5′(R)(CH2OH)HypH]-Val-NMe2 and Ac-Leu-d-Phe-[Glc3′(S)-5′(S)(CH2OH)HypH]-Val-NMe2 demonstrates the presence of β-turn conformations. Different turn structures were observed by changing the stereochemistry at 5′-position of Glc3′(S)-5′(R)(CH2OH)HypH. The major prolyl amide cis isomer of glucose-protected tetrapeptide Ac-Leu-d-Phe-[Glc(MOM)43′(S)-5′(R)(CH2OMOM)HypH]-Val-NMe211 and glucose unprotected Ac-Leu-d-Phe-[Glc3′(S)-5′(R)(CH2OH)HypH]-Val-NMe213 forms a type VI β-turn conformation. In contrast, the major prolyl amide trans rotamer of tetrapeptide Ac-Leu-d-Phe-[Glc(MOM)43′(S)-5′(S)(CH2OMOM)HypH]-Val-NMe212 conserves a similar β-turn conformation as the Gramicidin S-based peptide fragment Ac-Leu-d-Phe-Pro-Val-NMe216. 相似文献