Crosslinking is taking off here in Maryland, thanks primarily to the DSSO crosslinker and the Xlink nodes.
Okay -- I got distracted. If you are interested in why there is a protein structural revolution going on -- thanks to hardware, crosslinker, and software advancements -- check out this awesome open review from Andrea Sinz et al.,!
I particularly like the illustrations showing how the crosslinking molecules fit within the protein or between protein species. (It's open access, you'll have to check them out for yourself).
When you do look at the current crosslinkers you'll notice they're kind of long. DSSO is like 10 or 12 Angstroms (please note, funny symbols over the letters are missing due to blog author ignorance/laziness -- we're going to go with the letter A) long and others are even longer than this.
10 A is great if you're looking to link things together that aren't super close together, but what if you could link things that are only in extremely close proximity?!?
BOOM!
A 2.6 A MS-cleavable crosslinker! First off..."zero-length" does sound way cooler than 2.6 A. Let's check with Drake.
Now that this is put into perspective, I'm going to be serious for a second.
This is seriously powerful! First off -- these longer crosslinks can provide really valuable information on what proteins are interacting and when -- but can you imagine how much information DSSO plus CDI (the zero length reagent that performed the best) would provide?
DSSO -- this crosslinks
CDI - it doesn't
Right there -- you have information on the relative proximity of the residues in terms of their 3 dimensional structure! Information that I wouldn't know how to ever get otherwise. Maybe bug one of those NMR or crystal nerds...?
Best of all? CDI is MS-cleavable and provides a pattern almost identical to DSSO. Which means all these new tools, including the automated instrument methods the manufacturer has developed AND the Xlink nodes, R package, and Xlink 2.0 server should all directly accept data from this reagent.
What an amazing time to be doing structural proteomics!!
So this is a pretty cool development, and shorter cross-links definitely have some advantages. But I object to calling it the first zero length cross-linker. It is not zero length, as you mention, and it is not the first. EDC/NHS procedures have been around for a long time. EDC will form an amide bond between an amine and a carboxylic acid, so the cross-link is a single chemical bond--as close to zero length as you can get.
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