Courtesy of Amersham Biosciences
Researchers who need to purify large numbers of His- or GST-tagged proteins take note: A new robotic system can speed up the process. Piscataway, NJ-based Amersham Biosciences'
The standard ÄKTAxpress system, which can purify as much as 50 mg of target protein, contains four modules, each of which houses a pump, air sensor, UV detector, and integrated 96-well plate fraction collector. Four samples per module can be purified simultaneously, and each module can be programmed to run a different protocol. The system can be expanded to 12 modules and still be controlled by the same computer.
While most robotic chromatography systems are limited to a single purification step, ÄKTAxpress can purify proteins using His- or GST-tag affinity chromatography (AC), desalting (DS), gel filtration (GF), and/or ion-exchange chromatography (IEX). The steps can be combined or employed separately, depending on the level and type of purification desired. According to company literature, the typical run time for a four-step (AC-DS-IEX-GF), eight-sample purification is eight hours. The entire process can run unattended, leaving operators' time free for other tasks.
Twenty years ago, it took a week to purify one protein, says Andrzej Joachimiak, director of the Structural Biology Center at Argonne National Laboratory and a principal investigator with the Midwest Center for Structural Genomics (MCSG). The first laboratory to receive the ÄKTAxpress system, the MCSG is a major research consortium dedicated to mapping the entire repertoire of protein structures. "ÄKTAxpress has optimized our applications," says Joachimiak. "It's very simple to use, and it works very well."
Researchers in industry could also benefit. "Knowing which proteins do what will help scientists in the biotechnology and pharmaceutical industries achieve better success rates," says Fjarstedt. "You can lose up to 50% of your candidates if you work with proteins that aren't purified."
- Margaret Crane and Aileen Constans