Multistranded helix in xanthan polysaccharide

Area of Science:

• Biochemistry
• Materials Science
• Microbiology

Background:

• Xanthan gum is a versatile microbial extracellular polysaccharide.
• Its unique structural properties influence its functionality in various applications.
• Understanding xanthan's molecular architecture is crucial for optimizing its use.

Purpose of the Study:

• To elucidate the native and denatured structural characteristics of xanthan gum.
• To investigate the renaturation process and resulting fiber morphology.
• To provide insights into the molecular basis of xanthan's physical properties.

Main Methods:

• Electron microscopy was employed to visualize xanthan structures.
• Native xanthan samples were analyzed.
• Denaturation and renaturation protocols were applied, followed by microscopic examination.

Main Results:

• Native xanthan presents as an unbranched, likely double-stranded fiber (4 nm width, 2–10 µm length).
• Denaturation reduces xanthan to single strands (2 nm width, 0.3–1.8 µm length).
• Renatured xanthan exhibits short, unraveled regions with a right-handed twist of 2–3 strands.

Conclusions:

• Xanthan gum's structure is conformationally dynamic, transitioning between double and single strands.
• The fiber width and length are significantly altered by denaturation and renaturation.
• The observed structural changes provide a molecular explanation for xanthan's rheological behavior.