Physicochemical Approach to Understanding the Structure, Conformation, and Activity of Mannan Polysaccharides

Abstract

Extracellular polysaccharides are widely produced by bacteria, yeasts, and algae. These polymers are involved in several biological functions, such as bacteria adhesion to surface and biofilm formation, ion sequestering, protection from desiccation, and cryoprotection. The chemical characterization of these polymers is the starting point for obtaining relationships between their structures and their various functions. While this fundamental correlation is well reported and studied for the proteins, for the polysaccharides, this relationship is less intuitive. In this paper, we elucidate the chemical structure and conformational studies of a mannan exopolysaccharide from the permafrost isolated bacterium Psychrobacter arcticus strain 273-4. The mannan from the cold-adapted bacterium was compared with its dephosphorylated derivative and the commercial product from Saccharomyces cerevisiae . Starting from the chemical structure, we explored a new approach to deepen the study of the structure/activity relationship. A pool of physicochemical techniques, ranging from small-angle neutron scattering (SANS) and dynamic and static light scattering (DLS and SLS, respectively) to circular dichroism (CD) and cryo-transmission electron microscopy (cryo-TEM), have been used. Finally, the ice recrystallization inhibition activity of the polysaccharides was explored. The experimental evidence suggests that the mannan exopolysaccharide from P. arcticus bacterium has an efficient interaction with the water molecules, and it is structurally characterized by rigid-rod regions assuming a 14-helix-type conformation.

Spectroscopy Approach for Highly-Efficient Screening of Lectin-Ligand Interactions in Application for Mannose Receptor and Molecular Containers for Antibacterial Drugs

“…Conjugates 1–3 ( Supplement Figures S1, S2, S7 and S8 ) are oligomeric cyclodextrin’s meshes with mannose clusters; they have low-negative zeta-potential (–3–4 mV, because charged groups are virtually absent) and a high hydrodynamic diameter from 330 to 780 nm in accordance with the increase in molecular weight from 6 to 9 kDa and most significantly—the number of mannose clusters (mannose molecules from one spermine molecule) on spermine spacers from 3–5 to 10–15. This size (780 HM ) includes a shell of water around the conjugate, so for “sugar” conjugates, the size turns out to be large (as earlier reported for mannan 530–720 nm [ 57 ]). Products 1–2 contain linear and pyranose mannose residues that have been attached to activated OH groups of cyclodextrin.…”

Ice Recrystallization Inhibition Using l-Alanine/l-Lysine Copolymers

“…36 The MLGS values of mannose-type polysaccharides were 80 and 35% of those of PBS at 1.25 and 10 mg/mL, respectively. 48 Silk fibroin was reported to exhibit MLGS values of 80 and 40% of PBS at 10 and 40 mg/mL, respectively. 49 To conclude, the IRI activity of PAK was very high and similar to or better than that of PVA.…”

“…Cellulose nanocrystals exhibited MLGS values of 40 and 22% of PBS at 10.0 and 30.0 mg/mL, respectively . The MLGS values of mannose-type polysaccharides were 80 and 35% of those of PBS at 1.25 and 10 mg/mL, respectively . Silk fibroin was reported to exhibit MLGS values of 80 and 40% of PBS at 10 and 40 mg/mL, respectively .…”

Manipulating the Morphology of Amphiphilic Graft-Copolymer Assemblies by Adjusting the Flexibility of the Main Chain

“…Herein, we report the self-assembly behavior of three amphiphilic graft copolymers that consist of different hydrophilic main-chain polymers (dextran, poly­(2-hydroxypropyl methacrylamide) (PHPMA), and mannan , ) and a poly­(propylene oxide) (PPO) hydrophobic graft chain (Figure ). Although the degrees of substitution of the PPO chains were comparable, each graft copolymer was found to form, depending on the persistence length of the hydrophilic main chain, a different nanostructure: spheres, rods, or vesicles.…”