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Electron capture dissociation, electron detachment dissociation, and collision-induced dissociation of polyamidoamine (PAMAM) dendrimer ions with amino, amidoethanol, and sodium carboxylate surface groups.

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

Bottom Line: ECD and EDD of the PAMAM dendrimers resulted in simple mass spectra, which are straightforward to interpret, whereas CID produced complex mass spectra.CID of the PAMAM dendrimers showed a strong dependence on the nature of the surface group and occurred mostly in the outer generation.The results demonstrate the potential utility of ECD and EDD as a tool for the structural analysis of PAMAM dendrimers.

View Article: PubMed Central - PubMed

Affiliation: School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.

ABSTRACT
Here, we investigate the effect of the structure (generation) and nature of the surface groups of different polyamidoamine (PAMAM) dendrimers on electron-mediated dissociation, either electron capture dissociation (ECD) or electron detachment dissociation (EDD), and compare the fragmentation with that observed in collision-induced dissociation (CID). ECD and EDD of the PAMAM dendrimers resulted in simple mass spectra, which are straightforward to interpret, whereas CID produced complex mass spectra. The results show that electron-mediated dissociation (ECD and EDD) of PAMAM dendrimers does not depend on the nature of the surface group but tends to occur within the innermost generations. CID of the PAMAM dendrimers showed a strong dependence on the nature of the surface group and occurred mostly in the outer generation. The results demonstrate the potential utility of ECD and EDD as a tool for the structural analysis of PAMAM dendrimers.

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Proposed mechanism for loss of water from PAMAMG1NH2.
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grs4: Proposed mechanism for loss of water from PAMAMG1NH2.

Mentions: The collision-induced dissociation of [M + 4H]4+ ions of PAMAMG1NH2 (Figure 2, bottom), is dominated by loss of water; loss of two neutral fragments AG1 [CH2=C(OH)—N(H)—CH2—CH2—NH2, Δm = 102.0793, equivalent to AG2 in PAMAMG2OH] and BG1 [CH2=CH—C(O)—N(H)—CH2—CH2—NH2, Δm = 114.0793, equivalent to BG2 in PAMAMG2OH]; and combined losses of water and AG1 and BG1 in various stoichiometries (see Supplementary Table S-4). Such fragmentation behavior is quite surprising, particularly with regard to the CID of PAMAMG2OH, in which no loss of water was observed. We speculate that the unusual CID behavior of PAMAMG1NH2 dendrimer proceeds as shown in Scheme 4. The loss of water is pronounced probably because P is particularly stable as a result of charge delocalization between the two nitrogen atoms. This idea is supported by a recent study of deamination and dehydration processes of N-terminal glutamine in CID of protonated peptides [21]. Deamination and dehydration processes strongly depend on the presence of “mobile protons.” When mobile protons are present the predominant neutral loss process from N-terminal glutamine is elimination of water because of formation of a protonated five-member aminopyrroline ring. When no mobile protons are present, deamination is observed as a result of formation of a neutral pyrrolidinone ring. Both reactions depend on the charge state and stability. In the present case of quapruply protonated PAMAMG1NH2 ions, four protons are present and a maximum of four molecules of water are eliminated during CID. In contrast, CID of both singly and doubly charged PAMAMG1NH2 ions resulted in loss of ammonia but not loss of water [15]. Neutral losses observed in the CID of PAMAMG1NH2 depend on the charge state; for higher charge states, the dominant process is loss of water and, for lower charge states, elimination of NH3 is observed.


Electron capture dissociation, electron detachment dissociation, and collision-induced dissociation of polyamidoamine (PAMAM) dendrimer ions with amino, amidoethanol, and sodium carboxylate surface groups.

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

Proposed mechanism for loss of water from PAMAMG1NH2.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2571976&req=5

grs4: Proposed mechanism for loss of water from PAMAMG1NH2.
Mentions: The collision-induced dissociation of [M + 4H]4+ ions of PAMAMG1NH2 (Figure 2, bottom), is dominated by loss of water; loss of two neutral fragments AG1 [CH2=C(OH)—N(H)—CH2—CH2—NH2, Δm = 102.0793, equivalent to AG2 in PAMAMG2OH] and BG1 [CH2=CH—C(O)—N(H)—CH2—CH2—NH2, Δm = 114.0793, equivalent to BG2 in PAMAMG2OH]; and combined losses of water and AG1 and BG1 in various stoichiometries (see Supplementary Table S-4). Such fragmentation behavior is quite surprising, particularly with regard to the CID of PAMAMG2OH, in which no loss of water was observed. We speculate that the unusual CID behavior of PAMAMG1NH2 dendrimer proceeds as shown in Scheme 4. The loss of water is pronounced probably because P is particularly stable as a result of charge delocalization between the two nitrogen atoms. This idea is supported by a recent study of deamination and dehydration processes of N-terminal glutamine in CID of protonated peptides [21]. Deamination and dehydration processes strongly depend on the presence of “mobile protons.” When mobile protons are present the predominant neutral loss process from N-terminal glutamine is elimination of water because of formation of a protonated five-member aminopyrroline ring. When no mobile protons are present, deamination is observed as a result of formation of a neutral pyrrolidinone ring. Both reactions depend on the charge state and stability. In the present case of quapruply protonated PAMAMG1NH2 ions, four protons are present and a maximum of four molecules of water are eliminated during CID. In contrast, CID of both singly and doubly charged PAMAMG1NH2 ions resulted in loss of ammonia but not loss of water [15]. Neutral losses observed in the CID of PAMAMG1NH2 depend on the charge state; for higher charge states, the dominant process is loss of water and, for lower charge states, elimination of NH3 is observed.

Bottom Line: ECD and EDD of the PAMAM dendrimers resulted in simple mass spectra, which are straightforward to interpret, whereas CID produced complex mass spectra.CID of the PAMAM dendrimers showed a strong dependence on the nature of the surface group and occurred mostly in the outer generation.The results demonstrate the potential utility of ECD and EDD as a tool for the structural analysis of PAMAM dendrimers.

View Article: PubMed Central - PubMed

Affiliation: School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.

ABSTRACT
Here, we investigate the effect of the structure (generation) and nature of the surface groups of different polyamidoamine (PAMAM) dendrimers on electron-mediated dissociation, either electron capture dissociation (ECD) or electron detachment dissociation (EDD), and compare the fragmentation with that observed in collision-induced dissociation (CID). ECD and EDD of the PAMAM dendrimers resulted in simple mass spectra, which are straightforward to interpret, whereas CID produced complex mass spectra. The results show that electron-mediated dissociation (ECD and EDD) of PAMAM dendrimers does not depend on the nature of the surface group but tends to occur within the innermost generations. CID of the PAMAM dendrimers showed a strong dependence on the nature of the surface group and occurred mostly in the outer generation. The results demonstrate the potential utility of ECD and EDD as a tool for the structural analysis of PAMAM dendrimers.

Show MeSH
Related in: MedlinePlus