Solid-phase synthesis of serine-based glycosphingolipid analogues for preparation of glycoconjugate arrays

Abstract

Synthetic glycolipids with defined structures are important tools in the study of glycolipid biology. In this paper we describe a solid-phase synthesis of three galactosylated serine-based glycosphingolipid analogues using the novel linker 2-fluoro-4-(hydroxymethyl)-phenoxyacetic acid. Gel-phase (19)F-NMR spectroscopy was used to measure the yield and stereochemical outcome of the solid-phase glycosylations. Under NIS-TfOH promotion, alpha- and beta-selective glycosylations were performed at room temperature with thioglycoside donors carrying fluorine labelled protective groups. Finally, the glycolipids were covalently linked to microtiter plates and labelled lectins with different selectivity for alpha- and beta-galactosides could bind to the glycolipid arrays.

Carbamate Linker Strategy in Solid‐Phase Synthesis of Amino‐Functionalized Glycoconjugates for Attachment to Solid Surfaces and Investigation of Protein‐Carbohydrate Interactions

“…[16,17] This immobilization procedure required relatively large amounts of the valuable neoglycolipid, m concentrations in the coupling buffer, and thus a more efficient strategy would be beneficial. One strategy is based on the fact that two different amines efficiently crosslink through dialkyl squarate under mildly basic conditions.…”

“…In order to enable solid-phase synthesis a linker suitable for attachment of amines was needed and we decided to use a carbamatelinker strategy [18,19] based on the previously described linker [2-fluoro-4-(hydroxymethyl)phenoxy]acetic acid. [16] The carbamate linkage is expected to withstand conditions throughout the glycoconjugate synthesis and subsequent cleavage can be performed with acid of moderate strength, e.g. trifluoroacetic acid (TFA).…”

“…Tentagel TM are excellent for solid-phase glycoconjugate synthesis and gel-phase 19 F NMR spectroscopy. [20][21][22][23] Resin 4 [16] was converted into the carbonate 5 through base-catalyzed reaction with p-nitrophenyl chloroformate (Scheme 1). [18,19] Under basic conditions NFmoc-1,3-diaminopropane and N-Fmoc-1,6-diaminohexane reacted with the carbonate yielding the carbamate resin 6a and 6b.…”

“…[15] The serinebased neoglycolipid 2 is such an analog. [16,17] The synthesis of compound 2, subsequent conjugation to amino-functionalized plates and evaluation with lectins have been described. [16,17] In one report the synthesis was carried out on solid phase using a linker and protective groups containing fluorine that enable gel-phase 19 F NMR spectroscopy to measure yield and stereochemical outcome during synthesis.…”

“…[16,17] The synthesis of compound 2, subsequent conjugation to amino-functionalized plates and evaluation with lectins have been described. [16,17] In one report the synthesis was carried out on solid phase using a linker and protective groups containing fluorine that enable gel-phase 19 F NMR spectroscopy to measure yield and stereochemical outcome during synthesis. [16] The carboxylic acid in compound 2 was coupled to amino-functionalized microtiter plates and the resulting neoglycolipid surface was subsequently probed with biotin-labeled RCA 120 from Ricinus communis with affinity for α-and β-Gal, followed by horseradish peroxidase conjugated avidin (avidin-HRP) for detection.…”