Researchers at the University of Connecticut found that water plays a key role in how elastin helps tissues stretch and spring back. Published November 9 in Nature Communications, the study showed water molecules drive elasticity. "Elastin should be viewed as a coupled protein-water system," said Anna Tarakanova about the findings.
Every time your heart beats, your lungs expand, or your skin stretches, a remarkable protein called elastin helps your body return to its original shape. But what exactly gives this protein its elasticity? For more than 50 years, scientists have debated whether elastin's ability to stretch and recoil comes primarily from the protein's own flexibility or from its interactions with surrounding water molecules.
Now, researchers at the University of Connecticut College of Engineering have uncovered new evidence suggesting that water plays a much larger role than previously understood. In a study published November 9 in Nature Communications, Anna Tarakanova, associate professor in the School of Mechanical, Aerospace, and Manufacturing Engineering, and postdoctoral researcher Metehan Çam used advanced computer simulations to investigate the molecular mechanisms behind elastin's remarkable elasticity.
"Elastin is the body's natural spring," said Tarakanova. "It helps arteries expand and recoil with each heartbeat, allows the lungs to stretch and relax during breathing, and gives skin some of its ability to return to shape."
Water's role in elastin's recoil
Historically, one theory compared elastin to a rubber band, suggesting that stretching restricts the protein's molecular movements and creates a natural tendency to recoil. Another emphasized the role of water molecules surrounding the protein.
Both explanations involve entropy, a scientific concept describing the number of different ways molecules can move and arrange themselves.
Tarakanova and Çam found that stretching elastin exposes more of the protein's surface to water, drawing additional water molecules into a thin surrounding layer where they have less freedom of movement than water farther from the protein. When the protein relaxes, some of those molecules return to the surrounding liquid, regaining their freedom of movement.
"The protein's flexibility still matters, but hydration water makes the dominant contribution to the entropy changes we measured," said Çam.
Their findings build on earlier evidence supporting a water-driven mechanism while demonstrating that protein flexibility and water interactions both contribute to elastin's behavior.
"Elastin should be viewed as a coupled protein-water system," says Tarakanova. "Not simply a dry molecular spring."
Separating protein and water effects
To investigate these mechanisms, Tarakanova and Çam created an atom-by-atom computer model of a 225-amino-acid region of human tropoelastin, the molecular building block of elastin.
Using the specialized Anton 3 supercomputer at the Pittsburgh Supercomputing Center, made available by D.E. Shaw Research, the team tracked the protein's relaxed state for 60 microseconds and compared it with a fully extended reference state.
These simulations allowed the researchers to observe molecular movements and interactions that are difficult to capture experimentally. Unlike previous studies that generally measured the combined effects of protein and water, their approach enabled them to calculate each component's entropy separately.
Probing aging tissues and resilient biomaterials
Their discovery could have implications for research on aging, tissue degeneration, and the development of new biomaterials.
As people age, elastin fibers can undergo chemical modifications, and tissues such as arteries, skin, and lungs gradually lose some of their elasticity.
"Our results suggest that we should examine not only changes in elastin's structure, but also how those changes affect its interactions with water," says Tarakanova.
Future studies could investigate whether age-related chemical changes alter the water layer surrounding elastin, potentially providing new insights into tissue stiffness and declining resilience. The findings could also inform the development of elastin-inspired biomaterials designed to withstand repeated stretching, with potential applications in tissue engineering.
Looking ahead, Tarakanova and Çam plan to extend their computational models to study more complex systems, including multiple protein chains and the interconnected elastic fiber networks found in human tissues.
"Ultimately we hope to connect these molecular mechanisms with the mechanical behavior of tissues and engineered materials," said Çam.