In this case, after dissolving the salt in water, Needham's group then inserted a microbubble of that solution into immiscible decanol in a microscopic chamber. The water itself then dissolved into the decanol and left behind the salt, which also crystallized.
According to his group's Biophysical Journal report, while decanol has practically no tendency to dissolve in water, water has a high probability of dissolving in decanol, allowing the latter to be used as a "drying" agent to remove the former.
"So then we asked: what if we did the same thing with the protein albumin?" Needham said. "I expected to maybe get crystallized albumin," Needham recalled. "But, in just a few minutes, we instead formed a glassified microbead of protein on the tip of a micropipette, at a high density just a bit more dense than water itself. That protein glass is not a crystal. It's really a solid liquid."
Many proteins can be coaxed into forming crystals, solids created by repeating three dimensional patterns of atoms as surrounding water is removed. On the other hand, Needham said he was not really surprised that his protein samples instead formed into glasses, which are more unorganized assemblage of molecules that can still "flow" over very long time scales.
The water loss in his process is apparently too rapid for the molecules of big and irregular proteins to reorganize into a crystal form in such a short time, he explained.
Careful studies by his graduate student Rickard found that the decanol removed all the water that is not bound up in the proteins' molecular structures. And the remaining "bound" water was insufficient to support the growth of bacteria and fungi. Storing proteins as microbeads could thus preserve them.
Proteins are currently dried into clumpy, irregular powders by several industria
|Contact: Karl Leif Bates|