It's a pure protein that was reduced, reacted with heavy/light paracetamol and then digested. The advantage is that there are lots of twin ions in there. Because these twin-ions are mostly peptide derivatives, they come in multiple charge states which effectively gives us a few different doublet spacings. There are many separated by 6.0201 as before, a good number separated by 3.01005 and a few separated by 2.0067. We have removed any points with intensity <1000 to make the file smaller.