It’s no secret that water is critical to the way cells function, but a UMaine research team has now added a new view on water in proteins, the workhorses of cellular processes. Interactions with water molecules affect protein stability and function, but how and where those interactions occur is just now beginning to be understood. In a report published in the Proceedings of the National Academy of Sciences in December, 2004, UMaine researchers describe the conditions in which clusters of water molecules can penetrate the cavities of folded proteins. Such spaces have been regarded as hydrophobic, or water repellent.
According to UMaine chemist and co-author Jayendran Rasaiah, “the balance between hydrogen bonding and the water cavity interactions is critical in determining whether water enters (a protein molecule).” Interestingly, similar clusters of water molecules have been found in the gas phase, but “it came as a surprise that the same structures are also seen in non-polar cavities,” says Rasaiah. Co-authors are: S. Vaitheeswaran, a graduate student in physics who received his Ph.D. in 2004 and is now a postdoctoral fellow at the Institute of Physical Science and Technology at the University of Maryland; Hao Yin, graduate student in chemistry; and Gerhard Hummer of the National Institutes of Health. In 2001, Rasaiah and Hummer reported in Nature that water forms chains inside carbon nanotubes.