Water surrounding an elastic protein may contribute more to its entropic recoil than changes in the protein chain itself, according to a peer-reviewed simulation. Researchers studied a fragment of human tropoelastin, a building block of elastin. The findings describe a molecular energy balance in a model, with intact tissues and their cross-linked networks outside its scope.
Elastin helps arteries, skin and lungs recover their shape after stretching. A peer-reviewed computational study examined how the protein’s molecular building block and nearby water contribute to that recoil. Its model concerns a fragment of human tropoelastin in water. Comparing relaxed and extended states allowed the authors to separate changes in protein conformations from changes in the surrounding water and their interaction energies.[1]
Extension brought more water molecules into the first layer surrounding the protein. Water there remained more constrained than bulk water. In the model, that change contributed more to the loss of entropy, a measure related to the available molecular arrangements, than the protein’s own conformational change. Protein contacts also weakened while protein–water interactions strengthened, so opposing energy contributions accompanied the entropic effect.[1]
The model used a 225-amino-acid fragment, compared with 698 amino acids in the complete human protein. Native elastin also forms cross-linked networks surrounded by other tissue components. Those features lie beyond the isolated fragment. The findings identify water as the dominant entropic contributor within the simulated balance, rather than the sole origin of elasticity. More native-like networks are a proposed setting for further testing.[1]
