Needing a break from making lecture slides now and then, I'm excited to have this project to work on. I first posted a rough(er) version of it here on December 14th. My very good friend has just embarked on her independent academic career in a top-ranked chemistry department, and of course needs some graphics for her website. In her lab they use fancy mass spectrometry techniques to identify enzymes in their active state within complex biological systems - the proverbial needle in the haystack. A needle in a haystack could be found with a strong enough magnet though. Their problem is much much harder.  It's more like finding a needle in a needlestack. Wait, no, that would be easy. How about finding a specific needle in a needlestack? There we go. Let's say they want to find the needle in the needlestack that only sews up toe holes on pink sweatsocks, for example, and of those, only the ones that are currently in business. So they throw in a holey pink sweatsock. They wait for the needle to start sewing, and then pull out the sock. In the illustration above, an enzyme's reactive cysteine (needle) has been trapped upon reacting with (sewing) an iodoacetimide (pink sock). In the interest of full disclosure, I personally have as much experience with activity-based protein profiling as I do with sewing (that being none), so I may not be the most qualified to make this analogy.