Scanning tunneling microscopic images show a laminated structure for glycogen molecules

Area of Science:

• Biophysics
• Carbohydrate Chemistry
• Surface Science

Background:

• Glycogen, a glucose polymer, is crucial for energy storage in animals.
• The precise molecular structure and growth mechanism of glycogen remain incompletely understood.
• Previous structural studies often relied on indirect methods.

Purpose of the Study:

• To visualize individual glycogen molecules using Scanning Tunneling Microscopy (STM).
• To elucidate the surface morphology and infer the growth pattern of glycogen.
• To assess the utility of STM in determining polysaccharide structures.

Main Methods:

• Utilized Scanning Tunneling Microscopy (STM) to image glycogen molecules at the nanoscale.
• Analyzed high-resolution STM images to determine molecular shape and surface features.
• Correlated observed morphology with potential growth models.

Main Results:

• Individual glycogen molecules were observed to be ellipsoidal, with dimensions ranging from 20 to 60 nm.
• STM imaging revealed a distinct laminar or layered appearance on the molecular surfaces.
• The observed surface structure challenges the traditional model of radial growth from a central point.

Conclusions:

• Glycogen molecules exhibit an ellipsoidal shape, suggesting a non-spherical growth pattern.
• The laminar surface features imply growth may occur from an edge, forming a layered ellipsoid.
• STM is a powerful technique for resolving fine structural details of polysaccharides like glycogen.