Protein purified

(Penn State) chemical engineers have demonstrated proof of concept for a new protein purification process that combines ultrafiltration's high throughput with high specificity achievable through electrically-charged dyes that bind to the protein.

Ultrafiltration – the separation of one component of a solution from another component by means of pressure exerted on a semipermeable membrane - is widely used in the pharmaceutical industry, by milk and whey producers and in water purification. The new process promises to broaden the scope of ultrafiltration to more fine separations.

In the proof of concept experiments, the protein of interest was tagged with a small, commercially available, negatively-charged dye molecule that can be easily removed. When the solution to be purified flowed through a negatively-charged ultrafiltration membrane, the protein of interest, now negatively-charged because of the attached dye, was retained in higher proportion than when it wasn't tagged.

Dr. Andrew Zydney, professor of chemical engineering and a developer of the process, says, "Classically, in ultrafiltration, the size of the pores in the filter determined what could get through. Recent studies have demonstrated that additional retention can be achieved using electrically charged membranes if the protein were of like charge. However, these new experiments have shown that you can enhance retention for the same size pore by attaching a charged dye marker to the protein of interest to change its electrical charge."