Monthly Archives: October 2013

What is TMT?

TMT (tandem mass tags) are labeling reagents for comparative mass-spectrometry-based proteomics, a Thermo equivalent of iTRAQ. Most popular TMT are amine reactive, but SH-reactive tags are also available. Each isobaric TMT reagent has an amine-reactive NHS-ester group, a spacer arm, and a tandem MS reporter. Either intact proteins or their tryptic digests can be labeled, and up to 6 experimental conditions can be compared in terms of protein expression differences. You can find more information about TMT reagents here.

Our facility is capable of performing both TMT and iTRAQ experiments.


October 3, 2013

Still running Joana’s samples; should be done by 11 PM.

Today’s special: alphabet soup

Mass spectrometrists sometimes come up with interesting abbreviations for their techniques: MudPIT anyone? My personal favorite is EIEIO, electron-induced excitation in organics; too bad this term never made the official IUPAC list of definitions. Old McDonald had a farm

Don’t use obsolete terms in your publications, check out our MS Terms page. Can’t find a term? Let me know!

Am I going to get my sample back?

This is a legitimate question! After all, you worked hard to prepare that sample.

The answer is no, your sample is destroyed during the analysis. What happens? Molecules in your sample become ionized, enter the mass spectrometer, and eventually collide with the mass analyzer electrodes. Once a year or so, we open the instrument and clean off the electrodes.

On the bright side, we only need to destroy a small amount of your sample, less than a microgram.


October 2, 2013

Orbi is busy today and tomorrow: running 6 samples (and 6 blanks), 4 hours each! There are currently two more sample sets waiting.