DMTMM-mediated amidation of alginate oligosaccharides aimed at modulating their interaction with proteins

• Published in: Carbohydrate polymers 2018-03, Vol.184, p.427-434
• Main Authors: Labre, Flavien, Mathieu, Sophie, Chaud, Patricia, Morvan, Pierre-Yves, Vallée, Romuald, Helbert, William, Fort, Sébastien
• Format: Article
• Language: English
• Subjects: Alginate lyases; Alginate oligosaccharides; Amidation; Chemical Sciences; Concanavalin A - chemistry; Lectin; Lectins - chemistry; Magnetic Resonance Spectroscopy; Mannose - chemistry; Multivalency; Oligosaccharides - chemistry; Polysaccharide-Lyases - chemistry; Polysaccharide-Lyases - metabolism
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2017.12.069

•DMTMM promoted efficient amidation of alginate oligosaccharides (AOS).•AOS were functionalized with amino acids and carbohydrates.•Grafting conferred improved stability to AOS against alginate lyases.•Mannose-grafted AOS exhibited multivalent inhibition of Con A lectin. Alginate oligosaccharides (AOS) with a weight average molecular weight of 5 kDa were efficiently amidated with amino acids and carbohydrates in aqueous media in the presence of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMTMM). Here, alanine, leucine, serine, as well as mannose and rhamnose, were amidated at high yields with a good control of the degree of substitution (DS). Amino acid- and carbohydrate-grafted AOS showed improved stability against degradation by alginate lyases having different specificities. This enzyme resistance was correlated with the DS: hydrolysis was reduced by 60–70% for low DS (0.1), whereas AOS with DS ranging from 0.4 to 0.6 remained unhydrolyzed. Competitive inhibition assays demonstrated multivalent binding of mannose-amidated AOS to concanavalin A lectin. A 178-fold affinity enhancement was observed for AOSMan-0.38 (DS 0.38) over α-methyl-mannoside with an IC50 of 5.6 μM, lending further evidence for the promising potential of AOS as multivalent scaffolds.