Redox activity and multiple copper(I) coordination of 2His–2Cys oligopeptide

Abstract

Copper binding motifs with their molecular mechanisms of selective copper(I) recognition are essential molecules for acquiring copper ions, trafficking copper to specific locations and controlling the potentially damaging redox activities of copper in biochemical processes. The redox activity and multiple Cu(I) binding of an analog methanobactin peptide-2 (amb2) with the sequence acetyl-His1-Cys2-Tyr3-Pro4-His5-Cys6 was investigated using ion mobility-mass spectrometry (IM-MS) and UV-Vis spectrophotometry analyses. The Cu(II) titration of amb2 showed oxidation of amb2 via the formation of intra- and intermolecular Cys-Cys disulfide bridges and the multiple Cu(I) coordination by unoxidized amb2 or the partially oxidized dimer and trimer of amb2. The principal product of these reactions was [amb2 + 3Cu(I)](+) which probably coordinates the three Cu(I) ions via two bridging thiolate groups of Cys2 and Cys6 and the δN6 of the imidazole groups of His6, as determined by geometry optimized structures at the B3LYP/LanL2DZ level of theory. The products observed by IM-MS showed direct correlation to spectral changes associated with disulfide bond formation in the UV-Vis spectrophotometric study. The results show that IM-MS analysis is a powerful technique for unambiguously determining the major ion species produced during the redox and metal binding chemistry of oligopeptides.

Diversity in Gold Finger Structure Elucidated by Traveling‐Wave Ion Mobility Mass Spectrometry

“…[15] These results strengthen our analogy between "organic" and Lewis acid electrophiles and suggest that in addition to being useful probes of NC topography,the Au-based agents could provide arich source of targeted anti-HIV agents based on athiolate modification strategy. The observation of aurated a 5 showed that Cys 5 is ag old-binding site while the aurated y 9 is indicative of auration at either His 20 or His 24 .T he observation of aurated y 21 ,y [23][24][25] ,and y 27 is also consistent with the binding at His 20 /His 24 and Cys 5 (Figure 4c). The observation of aurated a 5 showed that Cys 5 is ag old-binding site while the aurated y 9 is indicative of auration at either His 20 or His 24 .T he observation of aurated y 21 ,y [23][24][25] ,and y 27 is also consistent with the binding at His 20 /His 24 and Cys 5 (Figure 4c).…”

“…[5,14] For{ AuF} derived from Sp1-F3, only one conformation was observed (for its MS/MS spectrum, see Figure 4c). The observation of aurated a 5 showed that Cys 5 is ag old-binding site while the aurated y 9 is indicative of auration at either His 20 or His 24 .T he observation of aurated y 21 ,y [23][24][25] ,and y 27 is also consistent with the binding at His 20 /His 24 and Cys 5 (Figure 4c). Thei dentified gold-binding fragments from the MS/MS spectrum are shown in Table S3.…”

“…[19,20] Ruthenium(II)peptide interactions studied by IM highlight the important role played by the ligand in determining the shape of the adduct formed. [23] In summary,w eh ave shown the utility of ion mobility measurements combined with MS/MS for the study of zinc finger proteins/metal-drug interactions.T he ion mobility experiments are rapid (ms timescale) and, when combined with MS/MS,w ill provide information not only on the shape and conformer profile,but also on metalation selectivity and reactivity. [22] Afurther relevant example is the assignment of Cu coordination sites on am ethanobactin model peptide with potential Cys 2 His 2 binding sites analogous to the Sp1-F3 case.…”

Comparison of the pH‐dependent formation of His and Cys heptapeptide complexes of nickel(II), copper(II), and zinc(II) as determined by ion mobility‐mass spectrometry

“…Our previous IM‐MS studies of metal binding have shown behavior that is closely correlated to that of the solution phase, because the covalent interactions between the metal ion and peptide are robust enough to be conserved during electrospray ionization (ESI). Previous studies included the methanobactin from Methylosinus trichosporium (mb‐OB3b) and analog methanobactin (amb) oligopeptides which replaced the two enethiol oxazolone binding sites of mb‐OB3b with the 2His‐2Cys binding motif . From solution‐phase chemistry, the amb 5A‐F (Figure A ‐ F ) would be expected to exhibit an overall charge based on the protonation state of their acidic and basic sites, ie, the C‐terminus carboxyl group (p K a ≈ 3), His (p K a ≈ 6.0), Cys (p K a ≈ 8.3), and Tyr (p K a ≈11.0) .…”

“…Previous studies included the methanobactin 3,4 from Methylosinus trichosporium (mb-OB3b) and analog methanobactin (amb) oligopeptides which replaced the two enethiol oxazolone binding sites of mb-OB3b with the 2His-2Cys binding motif. 1,[5][6][7] From solution-phase chemistry, the amb 5A-F ( Figure 1A-1F) would be expected to exhibit an overall charge based on the protonation state of their acidic and basic sites, ie, the Cterminus carboxyl group (pKa ≈ 3), His (pKa ≈ 6.0), Cys (pKa ≈ 8.3),…”