Photoactivable amino acid bioisosteres and mass spectrometry: snapshots of in vivo 3D protein structures.

From folded to crosslinked proteins. A new promising photo-crosslinking/mass spectrometry method for the structural characterisation of folded proteins is highlighted. A reactive photo-leucine can clamp the front residues in β-turn and β-hairpin domains, thus allowing us to look into the specific native 3D structure of proteins.