10.1021/ac201854a.s001
Sung Woo Heo
Sung Woo
Heo
Tae Su Choi
Tae Su
Choi
Kyung Man Park
Kyung Man
Park
Young Ho Ko
Young Ho
Ko
Seung Bin Kim
Seung Bin
Kim
Kimoon Kim
Kimoon
Kim
Hugh I. Kim
Hugh I.
Kim
Host–Guest Chemistry in the Gas Phase: Selected Fragmentations of CB[6]–Peptide Complexes at Lysine Residues and Its Utility to Probe the Structures of Small Proteins
American Chemical Society
2011
Gas Phase
fragment product
peptide
protein structures
theory calculations
Lys residue
Lysine Residues
Selected Fragmentations
protein structure
solution phase
CB
iminium ion
electrospray ionization mass spectrometry
MSn spectra
5 IPA ion threads
2011-10-15 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Host_Guest_Chemistry_in_the_Gas_Phase_Selected_Fragmentations_of_CB_6_Peptide_Complexes_at_Lysine_Residues_and_Its_Utility_to_Probe_the_Structures_of_Small_Proteins/2601832
The gas phase host–guest chemistry between cucurbit[6]uril (CB[6]) and peptide is investigated using electrospray ionization mass spectrometry (ESI-MS). CB[6] exhibits a high preference to interacting with a Lys residue in a peptide forming a CB[6]–peptide complex. Collisionally activated CB[6] complexes of peptides yield a common highly selective fragment product at <i>m</i>/<i>z</i> 549.2, corresponding to the doubly charged CB[6] complex of 5-iminiopentylammonium (5IPA). The process involves the formation of an internal iminium ion, which results from further fragments to an a-type ion from a y-type ion, and the resulting 5IPA ion threads through CB[6]. Numerous peptides are investigated to test the generality of the observed unique host–guest chemistry of CB[6]. Its potential utility in probing protein structures is demonstrated using CB[6] complexes of ubiquitin. Low-energy collision induced dissociation yields CB[6] complex fragments, and further MS<sup><i>n</i></sup> spectra reveal details of the CB[6] binding sites, which allow us to deduce the protein structure in the solution phase. The mechanisms and energetics of the observed reactions are evaluated using density functional theory calculations.