Triple-Helix Conformation of a Polysaccharide Determined with Light Scattering, AFM, and Molecular Dynamics Simulation

Abstract

The chain conformation of a β-glucan extracted from black fungus (BFP) was studied by static/dynamic light scattering, viscometry, atomic force microscopy (AFM), and molecular dynamics (MD) simulation. The Mark–Houwink equation and the relationship between M w and R g of BFP in water at 25 °C were determined to be [η] = 1.78 × 10–7 M w 1.6 and R g = 5 × 10–4 M w 0.9, and the molar mass per unit contour length (M L) and the persistence length (q) were 2724 ± 276 nm–1 and 230 ± 30 nm, respectively, indicating triple-helix conformation. Moreover, the stiff-chain lengths of the BFP fractions were visualized with AFM images, and their M L values were estimated to give a mean of 2212 nm–1, consistent with the above. Importantly, MD simulation confirmed that the triple helix was the most stable conformation of BFP. We identified, for the first time, the triple-helix chain conformation of BFP and also offered an alternative method for the characterization of the rigid macromolecules.

Biomimetic Glucan Particles with Aggregation-Induced Emission Characteristics for Noninvasive Monitoring of Transplant Immune Response

“…There is a cavity inside the triple helix structure with a pitch of 18.6 Å, which is consistent with the reported structure of triple helix polysaccharides. 64,65 Glycosyl side chains appeared on the outer surface of the helix. In addition, three secondary hydroxyl groups formed unequal hexagonal hydrogen bonds along the center of the spiral (Figure 3c), which is also consistent with previous reports.…”

Dynamic and Hierarchically Structured Networks with Tissue-like Mechanical Behavior

“…Previous molecular dynamic studies also indicated that the transformation of single helix to triple helix is energetically favorable. 18 Supporting Information Figure s1 compares the CD spectra of the gel before and after the stress-induced deformation. Clearly, the dominant conformation of curdlan chains on the nanofiber surfaces has transformed from single helix to triple helix.…”

A Review on the Structure and Anti-Diabetic (Type 2) Functions of β-Glucans

“…AFM can provide information on the chain length, chain diameter and even the M L of a β -glucan sample [ 58 ]. In addition to these experimental techniques, molecular dynamics simulations have been used as a tool to explore the conformation of polymers, which can help illustrate the chain movements and conformations of polymers in different solutions [ 32 ], although the results always depend on the assumed model.…”