New clues to how proteins dissolve and c...(a difference with profound biological si...)

Computer simulations and quantum calculations of how sodium and potassium bind to proteins were performed by Lubo Vrbka and his colleagues in the Pavel Jungwirth research group, working in the Czech Republic in 2006. Their work indicated that the large difference between the binding efficiency of the two cations (which are otherwise similar in many ways) were consonant with the Law of Matching Water Affinities. In essence, Vrbka's simulations and calculations supported the Law's theoretical predictions.

Still needed was what Saykally calls "a new class of experimental support, stronger than previous experiments." His team, working with colleagues at beamline 8.0.1 of the Advanced Light Source, had developed just such an approach. Incorporating liquid microjet technology into the high-vacuum environment of a synchrotron x-ray experiment has allowed the group to perform near-edge x-ray absorption fine structure (NEXAFS) measurements on liquid samples that would otherwise be difficult or impractical to measure with synchrotron radiation.

Janel Uejio, a graduate student of Saykally's, recalls how she first became involved in the selective-binding investigation. She was working overnight on a different project at the 8.0.1 beamline when the phone rang at three o'clock in the morning.

"Rich had just read Vrbka's paper and had a brainstorm," says Uejio. "He wanted me to use liquid microjet technology to measure the selective binding of sodium and potassium to formate and acetate, two simple carboxylate groups characteristic of proteins. At that hour, all I had on hand were acetic acid and sodium chloride and potassium chloride" -- essentially, vinegar and table salt -- "but even so, th
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