"We are trying to understand what exactly is making these materials so useful for separating proteins," Cramer said. "And what we are looking to uncover are the fundamental interactions within the chromatographic process that make the separations possible and efficient."
For this study, the researchers used several of the advanced research facilities within CBIS. Using the Microbiology and Fermentation Core, Cramer and his colleagues grew several mutants of a protein called ubiquitin. This group of modified proteins is referred to as a protein library.
To compare the difference between multimodal systems and more traditional chromatography, the team ran the library through a less sophisticated chromatography system called ion exchange chromatography, as well as the multimodal system. They found that there was very little to no difference in the binding of proteins to ligands in the traditional ion exchange system. In contrast, there were huge fluctuations in the binding of some of the different mutants within the multimodal system.
To delve further into why this happened, they input ubiquitin and the multimodal ligands into the massive 800 megahertz NMR at Rensselaer's CBIS. The NMR uses magnetic properties within organic materials to provide information on the minute molecular chemical properties of the material. From the NMR data, they were able to determine what part and type of the protein the ligands were binding to and how strongly they would bind. Their results validated the previous multimodal chromatography comparison experiments, showing that each of the protein mutants that strongly fluctuated in their binding strength in the multimodal chromatographic system were also the same ones identified with the NMR.
"This research is helping us develop a fundamental understanding of selectivity," Cramer said. Working with his te
|Contact: Gabrielle DeMarco|
Rensselaer Polytechnic Institute