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Electron capture dissociation and collision-induced dissociation of metal ion (Ag(+), Cu(2+), Zn(2+), Fe(2+), and Fe(3+)) complexes of polyamidoamine (PAMAM) dendrimers.

Kaczorowska MA, Cooper HJ - J. Am. Soc. Mass Spectrom. (2008)

Bottom Line: Complexes were of the form [PD + M + mH](5+) where PD = generation two PAMAM dendrimer with amidoethanol surface groups, M = metal ion, m = 2-4.The results suggest that complexes of Fe(3+) and Cu(2+) are coordinated via both core tertiary amines, whereas coordination of Ag(+) involves a single core tertiary amine.The Zn(2+) and Fe(2+) complexes do not appear to involve coordination by the dendrimer core.

View Article: PubMed Central - PubMed

Affiliation: School of Biosciences, College of Life and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.

ABSTRACT
The electron capture dissociation (ECD) and collision-induced dissociation (CID) of complexes of polyamidoamine (PAMAM) dendrimers with metal ions Ag(+), Cu(2+), Zn(2+), Fe(2+), and Fe(3+) were determined by Fourier transform ion cyclotron resonance mass spectrometry. Complexes were of the form [PD + M + mH](5+) where PD = generation two PAMAM dendrimer with amidoethanol surface groups, M = metal ion, m = 2-4. Complementary information regarding the site and coordination chemistry of the metal ions can be obtained from the two techniques. The results suggest that complexes of Fe(3+) and Cu(2+) are coordinated via both core tertiary amines, whereas coordination of Ag(+) involves a single core tertiary amine. The Zn(2+) and Fe(2+) complexes do not appear to involve coordination by the dendrimer core.

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CID FT-ICR mass spectrum of (a) [PD + Cu2+ + 3H]5+ ions; (b) [PD + Fe3+ + 2H]5+ ions. PD = PAMAM dendrimer. Cleavages between carbon atoms in the ethylenediamine core are marked in red.
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fig3: CID FT-ICR mass spectrum of (a) [PD + Cu2+ + 3H]5+ ions; (b) [PD + Fe3+ + 2H]5+ ions. PD = PAMAM dendrimer. Cleavages between carbon atoms in the ethylenediamine core are marked in red.

Mentions: The CID mass spectrum of the [PD + Cu2+ + 3H]5+ complex, shown in Figure 3a, reveals four intense signals, which can be assigned to [1/2PD + Cu2+]2+, [1/2PD + Cu2+ + H]3+, [1/2PD + 2H]2+, and [1/2PD + 3H]3+, respectively (fragments are detailed in Supplementary Table 3). These fragment ions are the result of cleavage between the two carbon atoms of the ethylenediamine core of the dendrimer ligand. Other abundant fragments, including [1/2PD − G2(Lout) + 3H]3+, [1/2PD − G0(z) + H]+ and [1/2PD − G1(z) + H]+ also involve cleavage in the core of dendrimer (marked red on the mass spectrum). (For comparison, Supplemental Figure 3 shows the CID mass spectrum of [PD + Cu2+ + 2H]4+. Similar fragmentation behavior was observed). That fragmentation behavior is particularly surprising considering the CID of protonated PAMAMG2OH dendrimers [19, 21], in which L and K cleavages, and combinations of the two cleavage types in various stoichiometries, from the outermost generation were the dominant processes. No core C–C bond cleavage was observed in the CID of protonated PAMAM precursor ions. The results suggest that the CID of the [PD + Cu2+ + 3H]5+ complex is linked with the coordination of the divalent copper ion to the PAMAMG2OH dendrimer ligand. As described above, it has been suggested that coordination of the Cu2+ ion involves the tertiary amines of the dendrimer core. Further evidence for that was provided by the ECD data obtained here. Two salient points arise from the CID data. Firstly, the Cu2+ ion is attached close to dendrimer core. That idea is supported by the fact that the Cu2+-containing fragment [PD + Cu2+ − G0(Kout) + 2H]4+, which arises through the loss of G0(Kout) from the innermost generation of the complex, is observed, but Cu2+-containing fragments from the outer generations, e.g., [Cu2++ G2(Kout) + nH](n + 2)+ or [Cu2+ +G1(Kout) + nH](n + 2)+, are not. Secondly, the abundance of fragments resulting from the cleavage of the core C–C bond suggests that both core tertiary amines coordinate the metal ion, and as a result the C–C bond is weakened.


Electron capture dissociation and collision-induced dissociation of metal ion (Ag(+), Cu(2+), Zn(2+), Fe(2+), and Fe(3+)) complexes of polyamidoamine (PAMAM) dendrimers.

Kaczorowska MA, Cooper HJ - J. Am. Soc. Mass Spectrom. (2008)

CID FT-ICR mass spectrum of (a) [PD + Cu2+ + 3H]5+ ions; (b) [PD + Fe3+ + 2H]5+ ions. PD = PAMAM dendrimer. Cleavages between carbon atoms in the ethylenediamine core are marked in red.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2667233&req=5

fig3: CID FT-ICR mass spectrum of (a) [PD + Cu2+ + 3H]5+ ions; (b) [PD + Fe3+ + 2H]5+ ions. PD = PAMAM dendrimer. Cleavages between carbon atoms in the ethylenediamine core are marked in red.
Mentions: The CID mass spectrum of the [PD + Cu2+ + 3H]5+ complex, shown in Figure 3a, reveals four intense signals, which can be assigned to [1/2PD + Cu2+]2+, [1/2PD + Cu2+ + H]3+, [1/2PD + 2H]2+, and [1/2PD + 3H]3+, respectively (fragments are detailed in Supplementary Table 3). These fragment ions are the result of cleavage between the two carbon atoms of the ethylenediamine core of the dendrimer ligand. Other abundant fragments, including [1/2PD − G2(Lout) + 3H]3+, [1/2PD − G0(z) + H]+ and [1/2PD − G1(z) + H]+ also involve cleavage in the core of dendrimer (marked red on the mass spectrum). (For comparison, Supplemental Figure 3 shows the CID mass spectrum of [PD + Cu2+ + 2H]4+. Similar fragmentation behavior was observed). That fragmentation behavior is particularly surprising considering the CID of protonated PAMAMG2OH dendrimers [19, 21], in which L and K cleavages, and combinations of the two cleavage types in various stoichiometries, from the outermost generation were the dominant processes. No core C–C bond cleavage was observed in the CID of protonated PAMAM precursor ions. The results suggest that the CID of the [PD + Cu2+ + 3H]5+ complex is linked with the coordination of the divalent copper ion to the PAMAMG2OH dendrimer ligand. As described above, it has been suggested that coordination of the Cu2+ ion involves the tertiary amines of the dendrimer core. Further evidence for that was provided by the ECD data obtained here. Two salient points arise from the CID data. Firstly, the Cu2+ ion is attached close to dendrimer core. That idea is supported by the fact that the Cu2+-containing fragment [PD + Cu2+ − G0(Kout) + 2H]4+, which arises through the loss of G0(Kout) from the innermost generation of the complex, is observed, but Cu2+-containing fragments from the outer generations, e.g., [Cu2++ G2(Kout) + nH](n + 2)+ or [Cu2+ +G1(Kout) + nH](n + 2)+, are not. Secondly, the abundance of fragments resulting from the cleavage of the core C–C bond suggests that both core tertiary amines coordinate the metal ion, and as a result the C–C bond is weakened.

Bottom Line: Complexes were of the form [PD + M + mH](5+) where PD = generation two PAMAM dendrimer with amidoethanol surface groups, M = metal ion, m = 2-4.The results suggest that complexes of Fe(3+) and Cu(2+) are coordinated via both core tertiary amines, whereas coordination of Ag(+) involves a single core tertiary amine.The Zn(2+) and Fe(2+) complexes do not appear to involve coordination by the dendrimer core.

View Article: PubMed Central - PubMed

Affiliation: School of Biosciences, College of Life and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.

ABSTRACT
The electron capture dissociation (ECD) and collision-induced dissociation (CID) of complexes of polyamidoamine (PAMAM) dendrimers with metal ions Ag(+), Cu(2+), Zn(2+), Fe(2+), and Fe(3+) were determined by Fourier transform ion cyclotron resonance mass spectrometry. Complexes were of the form [PD + M + mH](5+) where PD = generation two PAMAM dendrimer with amidoethanol surface groups, M = metal ion, m = 2-4. Complementary information regarding the site and coordination chemistry of the metal ions can be obtained from the two techniques. The results suggest that complexes of Fe(3+) and Cu(2+) are coordinated via both core tertiary amines, whereas coordination of Ag(+) involves a single core tertiary amine. The Zn(2+) and Fe(2+) complexes do not appear to involve coordination by the dendrimer core.

Show MeSH
Related in: MedlinePlus