Purifying Proteins with Chromatography
Thu, 12/06/2012 - 3:18pm
New platforms make processes faster and more flexible.
A scientist needs a purified sample of a protein to unravel its function. The complexity of acquiring such a purified protein depends largely on the complexity of the original sample. Most protocols for purifying proteins include some form—and maybe more than one—of chromatography. With the increasing development of protein-based drugs and the ongoing use of proteins as drug targets, researchers need advanced methods for creating purified proteins.
“All researchers want to deliver more in a shorter period of time, but they have less funding,” says Lotta Ljungqvist, PhD, head of R&D biotechnologies at GE Healthcare (Giles, U.K.). “We want to facilitate that work by making it faster and providing more flexible equipment.”
GE Healthcare’s new ÄKTA pure is a chromatography platform that can be used to purify proteins, peptides, and nucleic acids. “This system is built on modular hardware, so you can tailor it to your needs,” Ljungqvist explains. For example, a user can add various sampling systems that work with tubes or plates. In addition, a variety of detectors can also be added.
Beyond the hardware, the ÄKTA pure also includes innovative software. As Ljungqvist says, “I truly believe that good, intuitive software can help to guide a researcher in daily life.” The ÄKTA’s UNICORN 6 software provides many options for users. “If you’re new in the area of chromatography,” Ljungqvist says, “you can choose from our preloaded methods.” A user skilled in chromatographic methods can tweak the software for fine-tuning. “So this software fits both people in the beginning of using chromatography and the experts,” Ljungqvist says.
The applications of this platform already show its flexibility. “So far, we’ve seen it used in research labs and biopharma industry labs to purify proteins, in processes that range from one-step to very sophisticated methods,” Ljungqvist explains. This platform’s modularity also contributes to the breadth of applications. “You can quickly go back and forth between different methods,” Ljungqvist says. “You can add, for example, another valve or detector in just a minute.” Almost like working with Lego blocks, a scientist can build a new system. In making such changes, the software keeps track of the configuration and even lets the user know if a particular method will not work with the current collection of modules.
The flexibility and speed of the ÄKTA pure make protein purification more powerful than ever.
Pulling Out Peptides
Peptides comprise short strings of amino acids, from two to tens of residues. To purify peptides, says Marc Jacob, PhD, product manager, chiral and preparative chromatography at Phenomenex (Torrance, Calif.), “high-performance liquid chromatography, HPLC, is usually best.”
For peptides with molecular weights below 10,000 daltons, Phenomenex offers its Luna columns. Luna stationary phases come in a wide range of formats to work with peptides of different hydrophobicity. “The Luna C18 is the ‘go-to’ stationary phase for purification of peptides by HPLC, because of its high resolution and mechanical strength, which makes it very easy to purify compounds efficiently,” says Jacob. “Luna has been used in the purification of many therapeutics, including leuprolide, eptifibatide, bivalirudin, exenatide, fuseon, and insulin.”
For larger peptides, Phenomenex offers its Jupiter HPLC product line. These columns also come in several varieties for peptides of differing hydrophobicity. Well-known peptides and biosimilars—including human growth hormone, interferon, and pegylated peptides—can be purified with the Jupiter system.
Phenomenex is working on the next generation of Luna and Jupiter. With the variety of HPLC columns available, researchers can develop protocols to purify peptides on a range of scales.
About the author
Mike May is a publishing consultant for science and technology based in The Woodlands, Texas.