Chemical Synthesis and Enzymatic Testing of CMP‐Sialic Acid Derivatives

Abstract

The cycloSal approach has been used in the past for the synthesis of a range of phosphorylated bioconjugates. In those reports, cycloSal nucleotides were allowed to react with different phosphate nucleophiles. With glycopyranosyl phosphates as nucleophiles, diphosphate-linked sugar nucleotides were formed. Here, cycloSal-nucleotides were used to prepare monophosphate-linked sugar nucleotides successfully in high anomeric purity and high chemical yield. The method was successfully used for the synthesis of three nucleotide glycopyranoses as model compounds. The method was then applied to the syntheses of CMP-N-acetyl-neuraminic acids (CMP-Neu5NAc) and of four derivatives with different modifications at their amino functions (N-propanoyl, N-butanoyl, N-pentanoyl and N-cyclopropylcarbonyl). The compounds were used for initial enzymatic studies with a bacterial polysialyltransferase (polyST). Surprisingly, the enzyme showed marked differences in terms of utilisation of the four derivatives. The N-propanoyl, N-butanoyl, and N-pentanoyl derivatives were efficiently used in a first transfer with a fluorescently labelled trisialo-acceptor. However, elongation of the resulting tetrasialo-acceptors worsened progressively with the size of the N-acyl chain. The N-pentanoyl derivative allowed a single transfer, leading to a capped tetramer. The N-cyclopropylcarbonyl derivative was not transferred.

Prodrugs of Phosphonates and Phosphates: Crossing the Membrane Barrier

“…The biochemical and/or physiological basis for such significant differences in activity is/are not yet clear, but they clearly validate the effort devoted to diastereoselective syntheses and justify additional research into the cycloSal prodrugs. Applications of the cycloSal group as a leaving group in synthesis of 1,6-diglycopyranosyl-phosphates only further enhances the value of this group [75,76]. …”

Fluorescently Labeled Substrates for Monitoring α1,3‐Fucosyltransferase IX Activity

“…Furthermore, NDP‐sugars have been post‐synthetically modified 13. Recently we showed that the method can also be used for the synthesis of NMP‐sugars, for example, N ‐acetylneuraminic acid (derivatives) 14…”

Synthesis of a New Series of Sialylated Homo‐ and Heterovalent Glycoclusters by using Orthogonal Ligations

“…The NMR data is consistent with literature. [28] Methyl (Prop-2-ynyl 5-acetamido-3,5-dideoxy-d-glycero-a-dgalacto-2-nonulopyranosid)onate (3) Am ixture of 2 (2.81 g, 5.5 mmol), AgOTf (2.1 g, 8.2 mmol) and powdered 4 molecular sieves (4 g) in freshly distilled propargyl alcohol (60 mL) was stirred at room temperature under an Ar atmosphere. The reaction mixture was protected from light and stirred for 2h in the dark.…”