Enzymatic Synthesis of Artificial Polysaccharides

Abstract

Polysaccharides are the most important renewable polymers on Earth and hold an enormous potential for the production of ecofriendly functional materials. In addition to being sustainable, they have superior properties to synthetic polymers, particularly in the biomedical field where biocompatibility and biodegradability are vital. Derivatization of polysaccharides obtained from plant biomass paves the path forward for the design and manufacturing of advanced materials with specific properties adapted to meet definitive needs. However, these advances have been severely limited due to issues with establishing structure− property relationships, which are hampered by the heterogeneity of target polysaccharides and the random distribution of functional groups obtained after their chemical modification. An accurate correlation of structure−property relationships at multiple length scales requires substrates with defined sizes, sequences, and substitution patterns. Such tailor-made polysaccharides may be obtained by implementing a bottom-up approach, starting from monosaccharide or oligosaccharide building blocks followed by their polymerization and substitution through catalysis by different carbohydrate-active enzymes such as glycosynthases, phosphorylases, sucrases, and glycosyltransferases. Recent progress in the enzymatic synthesis of artificial polysaccharides is reviewed, with an emphasis on the potential of the synthesized products, either as new materials or as tools to study structure−property relationships. The obtained information will guide future developments of rationally designed biobased materials for industrial and biomedical applications.

Bacterial α-Glucan and Branching Sucrases from GH70 Family: Discovery, Structure–Function Relationship Studies and Engineering

“…However, despite a great diversity offering a strong potential for innovation, only a few of them—namely xanthan, gellan, hyaluronic acid, welan, clavan, fucopol, pullulan and dextran—are currently marketed [ 2 , 3 , 4 ]. Given the knowledge on polysaccharide synthetic pathways as well as the huge amount of available enzyme sequences and the progress made in protein and metabolic engineering, the supply of enzymatically or microbiologically produced polysaccharides, shaped on demand, is expected to rise significantly [ 5 , 6 ].…”

Progress and challenges in the synthesis of sequence controlled polysaccharides

“…A significant effort was put towards the development of enzymes for selective introduction of the side chains [ 97 – 98 ]. A detailed overview of the enzymatic strategies to generate artificial plant cell wall polymers was recently published [ 11 , 99 ]. Here, we describe the methods available to access well-defined XG oligo- and polysaccharides.…”

“…Control over the polysaccharide length (degree of polymerization, DP) and regioselective insertion of modifications or branches are additional challenges. Three main approaches are available (Figure 1): A) enzymatic polymerization [10][11][12][13][14][15][16][17], B) chemical polymerization [18], C) chemical synthesis.…”

“…Several classes of enzymes are available, including hydrolases, phosphorylases, sucrases, glycosyltransferases, and glycosynthases [19][20][21][22]. An excellent overview of the enzymes available for polysaccharide synthesis and their mode of action was recently published [11]. Despite the numerous advantages of this approach, limited enzyme availability as well as their high specificity narrowed the substrate scope.…”

Glycomacromolecules: Addressing challenges in drug delivery and therapeutic development

“…In this study, the conjugate constructed using the higher molecular weight oligosaccharide was shown to be more effective, suggesting that structural features of chitosan could be explored in order to optimise the efficacy of drug-delivery systems. Improvements in methods for the controlled preparation of oligo/polysaccharide materials through enzymatic 142 or solid-phase 143 approaches presents the opportunity to define structure-function relationships for these and other polysaccharide-based systems.…”