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Q&A: ASMS President Glish Dishes on Mass Spectrometry


glish2.JPGName: Gary Glish
Position: President, American Society for Mass Spectrometry, 2008 to 2010; vice president for programs, ASMS 2006 to 2008; professor of chemistry, University of North Carolina, 1992 to present.
Background: Research staff and group leader, Oak Ridge National Laboratory, 1980 to 1992; PhD, chemistry, Purdue University, 1980.

During the summer Gary Glish began his two-year term as president of the American Society for Mass Spectrometry. While he joked that the ASMS president primarily just "signs contracts," in truth, the position is responsible for the direction of the organization, which currently has about 7,000 members.

The Human Proteome Organization may be the de facto organizational voice for proteomics researchers, but ASMS is the main scientific resource for information about mass specs and tips on how to do better mass-spec experiments.

And though the instruments are being used for other purposes such as drug and chemical testing and food safety, proteomics researchers still comprise a significant portion of mass spec users.

ProteoMonitor recently spoke with Glish about where he thinks mass spec technology is going in proteomics. Below is an edited version of the conversation.

We're seeing from mass-spec vendors greater emphasis on the applied markets, food safety, and environmental testing, that sort of stuff. Do you see that shift happening within the research community and how it's using the instruments?

I think so. I think the biggest market is still probably in biotechnology, proteomics, and maybe metabolomics, and some of the emerging areas like that, so big pharma is probably a major user of the technology in terms of drug metabolism and pharmacokinetics. I know that's a big market.

And so the areas where there's lots of money is obviously where the vendors are orienting their products.

Talk a little bit about how the technology has evolved for proteomics. What can researchers do now with the instrument that maybe even five years ago they couldn't?

I think there [are] always new developments in how the technology is being used. The big revolution occurred in the late-80s, early-90s with the advent of electrospray and matrix-assisted laser desorption ionization. That allowed people then to apply the technology to proteins and readily apply it to peptides, interface it with liquid chromatography, things like that.

And more recently … [there have been] things like electron capture dissociation as a new way to probe for the structures of peptides and proteins and trying to improve our ability to identify these complex biomolecules.

I think you're finding in the last few years more incremental improvements in the instrumentation and what I would call hybrid instruments where you're combining two different types of mass spectrometers to make something that in total gives you more powerful techniques — things like the ion traps combined with an FTICR, or an ion trap combined with what's called an Orbitrap, where you get the high efficiency of tandem mass spectrometry experiments in the ion traps, but then you get the high resolution and accurate mass measurement of … the FTICR.

Or maybe even now, a time-of-flight — it's not the same magnitude of an FTICR, but the combination of ion traps or quadrupoles with time-of-flights. Even though the quadrupole time-of-flight instrument itself is rather old technology, some of the newer ones where they're combining ion traps are leading to some novel experiments, in particular where you can now combine electron capture dissociation or electron transfer dissociation to complement the old standby of collision induced dissociation as the activation method for tandem mass spectrometry.

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Have the greatest advancements come in sensitivity, or quantification, or the ability to look at post-translational modifications?

Sensitivity is one area where people are always trying to push the state of the art, and certainly that's where the big thing with electron capture dissociation, electron transfer dissociation is, for post-translational modifications. The dominant technique for ion activation where people do tandem mass spectrometry is collision induced dissociation, but it's much more difficult to get the post-translation modification information using CID versus ECD or ETD methodology.

I think that's been one of the things that's been driving the advancement of ECD and ETD.

Can you outline what you think are a few of the major technological breakthroughs recently in proteomics? Is it the ETD, the Orbitrap technology, the Synapt technology, or something else?

Those all are good examples of new technologies that are coming on to the marketplace. Each of them has different advantages that they offer … so there's not one mass spectrometer or one type of mass spectrometry that solves all problems.

Certainly, the Synapt and doing ion mobility gives you one type of data, and ETD experiments, or ECD experiments give you some complementary information oftentimes. The high resolution and accurate mass that you can get with the Orbitrap is certainly something that's been exciting in the marketplace.

What about the SELDI platform? Is there any future for that technology?

I'm not that familiar with the SELDI myself. I know that it's been touted for many, many years and hasn't had a major breakthrough yet. Certainly, there are some people using it and getting results, but it hasn't been ... a major player yet.

What needs do you think are not being met by mass-spec vendors?

I'm not sure that there are significant needs that are not being met. Certainly, everybody would like lower costs. It doesn't matter what the technology is … they always want lower costs and higher sensitivity and faster analysis.

But I think the vendors do a very good job. They've got multiple platforms that people can use depending on what their price range is or what their needs are. On the low end you've got the ion traps that are a major share of the market that are rugged and quite sensitive and very good at MS/MS but they don't have the resolution or mass accuracy that you might have with an FTICR.

But if you've got more money and you need the capabilities of the high resolution and mass accuracy of an FTICR or Orbitrap, those are available too.

Are there bottlenecks that you think technology is nowhere near solving?

I think a lot of the bottlenecks are on the front end with sample preparation, when you're trying to deal with extremely low quantities of samples, getting that from whatever organism that you're studying to the mass spectrometer is one of the bigger challenges these days.

The mass spectrometers are extremely sensitive, you can detect at femtomoles or even attamole levels, but …moving [an attamole sample] from point A to point B is a huge challenge, so I think you see a lot of work being done at instrument companies to address some of that.

And certainly at the back end, you can generate gigabytes of data and very quickly, and how to manipulate that data and extract useful information from data is a big challenge. I think certainly most of the bigger vendors are devoting a lot of resources to … data management or bioinformatics in some cases. And that's always going to be an issue: How do you handle the massive amounts of data that you can get?

You may be doing a 40-hour experiment and getting tens of thousands of spectra that you have to comb through to try to find the information that you're looking for.

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One of the criticisms I hear is that people who work with mass spectrometers are gearheads who don't understand the biology that should go hand in hand with the technology. What's your thought on that?

I think there are two camps. I think that there are people who are like that. I think that there are people on the other side who understand the biology but maybe don't understand the mass spectrometry as much.

And that's where I think as a society and at our annual conference, we bring those people together so that they can interact and have people who understand the biology and people who understand the instrumentation.

One criticism of the vendors would probably be that they tout the instruments as 'Anyone can use them,' basically, but I've seen more and more examples of people who are using them but don't really understand what the data means, and they're probably chasing after ghosts because they've identified something that really isn't there because of the way the data was acquired, or just false-positives, things like that.

It's certainly a valid criticism that there are some people who don't understand the biology, but the flip side is that you've got the biology people and some of them don't understand the instrumentation. And a goal of the society should be to bring those people together.

Does ASMS get involved in funding issues? One vendor recently said that one of the things that they're concentrating on is second-generation sequencing because there's a lot of government funding for that technology so there are more opportunities to do business there, whereas for mass-spec driven research, there isn't much funding around.

It's certainly something that's been talked about and we're involved a little bit in an organization called the Bridging [the Sciences] Coalition that sort of tries to educate the people in Washington, the funders, that there is a place for the development of this technology along with the application of the technology.

And NIH does have some study sections that are devoted toward technology, so there's a section … that's oriented more oriented toward analytical chemistry development. There's mass spectrometry and there's electrochemistry and sensors and things like that that go through there.

But it's certainly a concern: Where is the next generation of instrumentation coming from? Some people think it should just come from the instrument companies, but the instrument companies are sometimes short-sighted in terms of where their current markets are. The bigger ones can afford to devote some resources further out into the future but some of the smaller ones, I don't think, can do that.

What are you working on in your lab?

We work on in my lab … instrument development and ion activation for tandem mass spectrometry. We've done a lot of work in the last 20 years in the development of quadrupole ion traps. Early on we were the first lab to build a quadrupole time-of-flight mass spectrometer back in the '80s.

I didn't do much research in that for a while, and now we're back doing that. We've got a collaboration with Hitachi where we're using ion trap time-of-flight with an electron capture dissociation cell in it that was developed in collaboration with them.

What would be the application for that platform?

That would be a proteomics-type platform doing LC-MS, so it's sort of comparable to the linear ion trap FTICR or linear ion trap Orbitrap where they do ETD. In this case, we're doing ECD. We're studying more some of the fundamentals of the processes, trying to understand it, so that we can, hopefully, make it a better technique and apply it to a wider range of compounds.

My own feeling is that if we can understand the underlying chemistry and physics, we can use it better and understand the results that we get better and not make mistakes in terms of interpreting spectra.

What platforms interest you, that make you say, 'I wish I had invented that'?

There are lots of things out there that are interesting. We're interested in combining ion mobility with mass spectrometry. That's what the Syapt does and we … recently built a FAIMS device, so a high-field asymmetric ion mobility, mass spec. I think that's been a big growth area in the last eight to 10 years, the ion mobility combined with mass spectrometry, or even complementing mass spectrometry.

And again … when I say we want to go into three-dimensional structure of ions in the gas phase, ion mobility will play a role in that in some cases.

How far are you from achieving that?

I think it's a ways before we get to big ions. Right now we just recently built a FAIMS device and interfaced that to a quadrupole system and now we want to build a bigger instrument that allows us to use other types of probes to look at the three-dimensional structure.

The FAIMS device ion mobility is a way to select and hopefully purify a structure, because oftentimes, when you do an electrospray of these things or if you do MALDI, you get multiple structures of the ion, even if they have the same mass-to-charge.

The mass spectrometer can't tell you you've got multiple structures, but if you do ion mobility, then you can find out you have multiple structures. And if you can use the ion mobility like with the FAIMS to isolate one particular structure, then you can start studying that in detail and compare it to the other structures that do have the same mass-to-charge and see if you can understand how these structures have changed and the chemistry when you do things like CID or ECD and how that changes the results you get.

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