Construction and Structural Characterization of Versatile Lactosaminoglycan-Related Compound Library for the Synthesis of Complex Glycopeptides and Glycosphingolipids

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• 作者：Kentarou Naruchi ; Tomoki Hamamoto ; Masaki Kurogochi ; Hiroshi Hinou ; Hiroki Shimizu ; Takahiko Matsushita ; Naoki Fujitani ; Hirosato Kondo ; Shin-Ichiro Nishimura
• 刊名：Journal of Organic Chemistry
• 出版年：2006
• 出版时间：December 22, 2006
• 年：2006
• 卷：71
• 期：26
• 页码：9609 - 9621
• 全文大小：445K
• 年卷期：v.71,no.26(December 22, 2006)
• ISSN：1520-6904

文摘

We have established a facile and efficient protocol for the preparative-scale synthesis of various compoundlibraries related to lactosaminoglycans: cell surface oligosaccharides composed of N-acetyllactosamineas a repeating disaccharide unit, based on chemical and enzymatic approaches. Substrate specificity andfeasibility of a bacterial glycosyltransferase, Neisseria meningitidis 1,3-N-acetylglucosaminyltransferase(LgtA), were investigated in order to synthesize various key intermediates suited for the construction ofmammalian O-glycopeptides and glycosphingolipids containing poly-N-acetyllactosamine structures.Recombinant LgtA exhibited the highest glycosyltransferase activity with strongly basic conditions (pH= 10, glycine-NaOH buffer) and a broad range of optimal temperatures from 20 to 30 C. Interestingly,it was found that LgtA discriminates L-serine and L-threonine and functions both as a core-1 1,3-N-acetylglucosaminyltransferase and core-2 1,3-N-acetylglucosaminyltransferase toward Fmoc-Ser derivatives, while LgtA showed only core-2 1,3-N-acetylglucosaminyltransferase activity in the presence ofFmoc-Thr derivatives. Combined use of LgtA with human 1,4-galactosyltransferase allowed for controlledsugar extension reactions from synthetic sugar amino acids and gave synthetic lactosaminoglycans, suchas a decasaccharide derivative, Gal(1 4)GlcNAc(1 3)Gal(1 4)GlcNAc(1 3)Gal(1 4)GlcNAc(1 3)Gal(1 4)GlcNAc(1 6)[Gal(1 3)]GalNAc1 Fmoc-Ser-OH (6), and adodecasaccharide derivative, Gal(1 4)GlcNAc(1 3)Gal(1 4)GlcNAc(1 3)Gal(1 4)GlcNAc(1 6)[Gal(1 4)GlcNAc(1 3)Gal(1 4)GlcNAc(1 3)Gal(1 3)]GalNAc1 Fmoc-Ser-OH (9). A partially protected pentasaccharide intermediate, GlcNAc(1 3)Gal(1 4)GlcNAc(1 6)[Gal(1 3)]GalNAc1 Fmoc-Thr-OH (11), was applied for the microwave-assistedsolid-phase synthesis of a MUC1-related glycopeptide 19 (MW = 2610.1). The findings suggest thatthis sugar extension strategy can be employed for the modification of lactosyl ceramide mimetic polymersto afford convenient precursors for the synthesis of various glycosphingolipids.