Binding motifs of silver in prion octarepeat model peptides: a joint ion mobility, IR and UV spectroscopies, and theoretical approach.
Transition metal-ion complexation is essential to the function and structural stability of many proteins. We studied silver complexation with the octarepeat motif ProHisGlyGlyGlyTrpGlyGln of the prion protein, which shows competitive sites for metal chelation including amide, indole and imidazole groups. This octapeptide is known as a favourable transition metal binding site in prion protein. We used ion mobility spectrometry (IMS), infrared multiple photon dissociation (IRMPD) spectroscopy and density functional theory calculations (DFT) to identify the binding motifs of a silver cation on HisGlyGlyGlyTrp peptide as well as on peptide subsequences. Ultra-violet photodissociation (UVPD) and collision induced dissociation mass spectrometry together with the time-dependent density functional method was then exploited to study the influence of binding sites on optical properties and on the ground and excited states reactivity of the peptide. We show that the metal cation is bound to the π-system of the indole group and a nitrogen atom of the imidazole group and that charge transfers from the indole group to the silver cation occur in excited electronic states.
Université Lyon 1, Villeurbanne, CNRS, UMR5579, LASIM, Université de Lyon, F-69622, Lyon, France.
Bruno
B
Bellina
Isabelle
I
Compagnon
Luke
L
MacAleese
Fabien
F
Chirot
Jérôme
J
Lemoine
Philippe
P
Maître
Michel
M
Broyer
Rodolphe
R
Antoine
Alexander
A
Kulesza
Roland
R
Mitrić
Vlasta
V
Bonačić-Koutecký
Philippe
P
Dugourd
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001665:Binding Sites; D002412:Cations / Q000378:metabolism; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D011328:Prions / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D012834:Silver / Q000378:metabolism*; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet
D002412:Cations; D010455:Peptides; D011328:Prions; D012834:Silver