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A Whole New MALDI

  • Title: Research Associate, Department of Chemistry, Indiana University
  • Education: PhD, Max Planck Institute of Polymer Research, University of Mainz, 2002
  • Recommended by: David Clemmer

Improving upon one of the core technologies in mass spectrometry before your first professional appointment is no small feat. But Sarah Trimpin did just that by developing a technique that expands the use of MALDI, a solvent-based soft ionization mass spec tool used for probing fragile molecules such as peptides and proteins. “There are limitations with the solvent-based MALDI in that you do not correctly transfer the samples, so there is sample loss involved, and you cannot ionize them either, so even though they might be in the mass spectrometer, they are not ionized so you cannot detect them,” says Trimpin.

She first recognized the problem while working on her master’s degree in Germany, where she was researching amyloid peptides and amyloid. “There are a large number of proteins that are not soluble; for example, 75 percent of membrane proteins are commonly hydrophobic amino acids,” Trimpin says. “The methods used in proteomics analyses these days can only actually analyze around 25 percent of the protein, so if a biochemist goes to open a cell to look at the proteins that are floating around, they can only look at the very limited amount of proteins because of the techniques available.”

She says that what first attracted her to mass spec is the endless opportunity to examine the complexity of biomolecules. “There is no other method out there that can detect anything in such small amounts,” she says.

During her doctoral studies, she developed solvent-free MALDI for polymers and later, while a postdoc, expanded the technology to effectively ionize peptides and proteins. She acknowledges that, at first, her solvent-free MALDI was met with some skepticism within the mass spec community. When MALDI was first developed in the late 1980s, it was believed that in order for the laser to efficiently ionize the molecules, they had to be isolated under very strict conditions involving solvents. Trimpin, however, proved that her solvent-free approach not only allowed the process to work in the same way, but actually sometimes yielded better results. “You have to understand that solvent-free MALDI goes entirely against what was believed for the last 20 years almost, so it was very different,” she says. “That is why it was difficult to establish, but I just knew from my PhD that you have to think differently to achieve something, so it has just worked out wonderfully.”

Looking ahead

Trimpin hopes to further expand membrane proteomics with her solvent-free technique in the near future. Her plan is to “tackle … membrane proteomics, which is limited to 25 percent of the protein that they can look at because all the other amino acids after membrane proteins are within the cell membrane and are insoluble, and thus are not detectable with any mass spec method right now.”

Trimpin would also like to see more efficient data analysis solutions. She says that more developed computational tools, such as two-dimensional data analysis, could really aid in the process of interpreting data, because that is where the real bottleneck is.

Publications of note

Trimpin recently published a paper entitled “Solvent-free MALDI-MS for the Analysis of ß-Amyloid Peptides via the Mini-Ball Mill Approach: Qualitative and Quantitative Improvements” in the Journal for the American Society of Mass Spectrometry. In it, she compared her solvent-free MALDI method to traditional mass spec methods and demonstrated the ionization deficiencies resulting from solvent-based MALDI relative to her solvent-free approach.

And the Nobel goes to…

Trimpin hopes that her hypothetical Nobel is awarded for developing a technology that would improve solvent-free analyses of complex mixtures.

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