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Prompt Chemoenzymatic Synthesis of Diverse Complex‐Type Oligosaccharides and Its Application to the Solid‐Phase Synthesis of a Glycopeptide with Asn‐Linked Sialyl‐undeca‐ and Asialo‐nonasaccharides
Author(s) -
Kajihara Yasuhiro,
Suzuki Yasuhiro,
Yamamoto Naoki,
Sasaki Ken,
Sakakibara Tohru,
Juneja Lekh Raj
Publication year - 2004
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200305115
Subject(s) - glycopeptide , chemistry , asparagine , glycoside hydrolase , hydrolysis , sialic acid , oligosaccharide , neuraminidase , beta (programming language) , chromatography , solid phase synthesis , biochemistry , enzyme , stereochemistry , peptide , programming language , computer science , antibiotics
We describe herein the preparation of 24 pure asparagine‐linked oligosaccharides (Asn‐oligosaccharides) from asparagine‐linked biantennary complex‐type sialylundecasaccharide [(NeuAc‐α‐2,6‐Gal‐β‐1,4‐GlcNAc‐β‐1,2‐Man‐α‐1,6/1,3‐) 2 ‐Man‐β‐1,4‐GlcNAc‐β‐1,4‐GlcNAc‐β‐1‐asparagine, 2 ] obtained from egg yolk. Our synthetic strategy aimed at adapting branch specific exo‐glycosidases digestion (β‐ D ‐galactosidase, N‐acetyl‐β‐ D ‐glucosaminidase and α‐ D ‐mannosidase) of the individual asialo‐branch after preparation of monosialyloligosaccharides obtained from 2 by acid hydrolysis of NeuAc. In order to perform branch specific exo‐glycosidase digestion, isolation of pure monosialyloligosaccharides obtained was essential. However, isolation of two kinds of monosialyloligosaccharides are difficult by HPLC due to their highly hydrophilic nature. Therefore, we examined chemical protection with hydrophobic protecting (Fmoc and benzyl) groups. These chemical protection enabled us to separate the monosialyloligosaccharides by use of a HPLC column (ODS) on synthetic scales. Using these pure monosialiloligosaccharides enable us to obtain 24 Asn‐linked oligosaccharides (100 mg scale) within a few weeks by branch specific exo‐glycosidase digestions (α‐ D ‐neuraminidase, β‐ D ‐galactosidase, N‐acetyl‐β‐ D ‐glucosaminidase and α‐ D ‐mannosidase). In addition, solid‐phase synthesis of glycopeptide having Asn‐linked sialyl‐undeca‐ and asialo‐nonasaccharides thus obtained, was also performed on an acid labile HMPA‐PEGA resin.