SEP 07, 2017 6:00 AM PDT

Surprise! Sugar Molecules Can Form Rigid Structures After all

An oligosaccharide is a small polymer that typically has three to ten individual sugar molecules. Most naturally occurring oligosaccharides can be found in plants. For example, Raffinose, a trisaccharide consisting of galactose, glucose, and fructose, are present in vegetables like beans, cabbage, and brussels sprouts. Oligosaccharides can form conjugates by bonding to amino acid side-chains in proteins or to lipid moieties. Oligosaccharides and their conjugates have many functions in human body. Glycolipids the sugar-coupled fat molecules on the outer cellular membrane can help immune system distinguish the body's own cells from pathogens or other foreign cells. Nutrients wise, oligosaccharides are considered one of the main source of prebiotics. Prebiotics are the broken-down food components that support the growth of certain beneficial bacteria in the colon.

The oligosaccharide that comprises three sugars can form a rigid structure, thanks to a hydrogen bond (dotted line) between Carbon-Hydrogen bond in the upper molecule (red) and Oxygen between two Carbons in the lower molecule (yellow).

Credit: Chemistry

Oligosaccharides were previously thought to be flexible. The individual sugar molecules in the chain are supposed to behave like beads on a string: they can rotate on their position as long as their functional groups do not hinder the motion. Many naturally existing polymers of amino acids or nucleotides cannot do the same - different units within the polymer chain can form hydrogen bond(s), resulting in the so-called secondary structures. These structures are three-dimensional formations, such as the double helix in DNAs or the spirals and pockets in proteins.

Recently the discovery made by an international research team has changed this assumption. Using NMR structure determination and database searches, the researchers identified numerous trisaccharide polymers, all of which contain a fucose, can form a non-conventional C−H⋅⋅⋅O hydrogen bond, which gives these polymers a characteristic rigidity. What is more important, these trisaccharides are the basic building blocks in numerous classes of oligosaccharides found in everything from bacteria to mammals.

This finding disproves a long-standing dogma that the hydrogen bonds between oligosaccharide building blocks are too weak to form any secondary structure. "Our work now shows that certain hydrogen bonds have to be taken into account. As a slight tip of the scales, they can help significantly in forcing the sugar building blocks into a rigid corset," says Dr. Mario Schubert, the head of the research team and a structural biologist at the University of Salzburg. "Oligosaccharides with the newly discovered structural pattern are recognized easily by other molecules using the lock and key principle because a rigid, inflexible structure simplifies molecular recognition." He hopes that their discovery can help to better understand the interactions between oligosaccharides-bearing immune system molecules and stem cells.

Biochemistry of Carbohydrate. Credit: Armando Hasudungan

Source: Chemistry / Phys.org

About the Author
  • Graduated with a bachelor degree in Pharmaceutical Science and a master degree in neuropharmacology, Daniel is a radiopharmaceutical and radiobiology expert based in Ottawa, Canada. With years of experience in biomedical R&D, Daniel is very into writing. He is constantly fascinated by what's happening in the world of science. He hopes to capture the public's interest and promote scientific literacy with his trending news articles. The recurring topics in his Chemistry & Physics trending news section include alternative energy, material science, theoretical physics, medical imaging, and green chemistry.
You May Also Like
OCT 17, 2019
Chemistry & Physics
OCT 17, 2019
A Natural, Eco-friendly Pesticide Synthesized for the First Time
A group of organic chemists at California Institute of Technology has come up with a synthesis method to produce a naturally existing pesticide named &mdas...
NOV 26, 2019
Space & Astronomy
NOV 26, 2019
Jupiter's Great Red Spot is as Powerful as it is Captivating
Jupiter is the largest known planet in our solar system, but even that isn’t the gas giant’s most discernible feature – that title belong...
JAN 05, 2020
Space & Astronomy
JAN 05, 2020
Is Betelgeuse on the Verge of Going Supernova?
There’s been a lot of discussion happening as of late with respect to the Orion constellation’s red supergiant star Betelgeuse. Being one of th...
JAN 13, 2020
Space & Astronomy
JAN 13, 2020
Lunar Dust is Actually Quite Dangerous to Humans
Most people have a tendency to think that lunar dust isn’t any different than the dirt found here on Earth, but quite the opposite is true. In fact,...
FEB 04, 2020
Chemistry & Physics
FEB 04, 2020
A Gamma-Ray Burst Like Nothing Else Before
Gamma-ray bursts (GRB) are among the most explosive and energetic celestial events that have been observed by astronomers. Since its first detection back i...
FEB 10, 2020
Chemistry & Physics
FEB 10, 2020
Portable Biofactories that Can Crank Out Medicine On-Demand
A hydrogel is a water-dispersed, polymer colloid that's been popularly explored in biomedicine. A collaborative project between the University of Texas...
Loading Comments...