Shape changes induced by N-terminal platination of ubiquitin by cisplatin.
The three-dimensional conformation of a protein is an important property and plays a key role in its biological activity. We show here that ion mobility-mass spectrometry (IM-MS) can be used to detect conformational changes in the protein ubiquitin in the gas phase induced by reaction with the anticancer drug cisplatin. The primary adduct was ubiquitin-{Pt(NH(3))(2)} under denaturing conditions. Up to three different conformations appear to be generated upon platination depending on the charge state. The collision cross-sections (Omega) for each conformation indicate that the conformations of the platinated protein are contracted in size compared with unmodified ubiquitin with generally smaller Omega values. Ion mobility-tandem MS allowed determination of the platinum binding site without a requirement for prior chromatographic separation. A rapid 30-min digestion of cisplatin-modified ubiquitin with trypsin allowed the platination site to be identified as the N-terminal methionine following low-energy collision-induced dissociation (CID) studies of the modified peptide. The data were generated using a Traveling-Wave based ion mobility-MS approach. Such cisplatin-induced shape changes may have a significant effect on its function in vivo. This work highlights the usefulness of the ion-mobility mass spectrometry technique for shedding new light on such protein interactions.
Department of Chemistry, University of Warwick, Coventry, United Kingdom. Jonathan_Williams@waters.com
Jonathan P
JP
Williams
Hazel I A
HI
Phillips
Iain
I
Campuzano
Peter J
PJ
Sadler
D000818:Animals; D002417:Cattle; D002945:Cisplatin / Q000737:chemistry / Q000378:metabolism*; D004912:Erythrocytes / Q000737:chemistry; D007477:Ions / Q000737:chemistry / Q000378:metabolism; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods; D014357:Trypsin / Q000378:metabolism; D025801:Ubiquitin / Q000737:chemistry / Q000378:metabolism
D007477:Ions; D010446:Peptide Fragments; D025801:Ubiquitin; D014357:Trypsin; D002945:Cisplatin