Electrospray ionization multi-stage mass spectrometric study of the interaction products of the cytotoxic complex [Cu(thp)4][PF6] with methionine-rich model peptides.
Rapid Commun Mass Spectrom
; 29(3): 253-62, 2015 Feb 15.
Article
em En
| MEDLINE
| ID: mdl-26411623
ABSTRACT
RATIONALE The cytotoxic activity of the copper(I) complex [Cu(thp)4][PF6] (CP) (thp = tris(hydroxymethyl) phosphine) is correlated with its high accumulation in cancer cells. Human copper transporter 1 (hCtr1) has been described as the main trans-membrane protein involved in cellular trafficking of physiological copper. Methionine-rich peptide sequences incorporated in the extracellular domain of hCtr1 play a key role in the cellular internalization of copper. We wish to investigate the interaction of CP with model peptides that mimic the extracellular domain of hCtr1. METHODS:
The interaction of CP with methionine-rich and methionine-free model peptides has been investigated by electrospray ionization mass spectrometry and the interaction products have been characterized by multiple collisional experiments, using an ion trap mass instrument.RESULTS:
The interaction of CP with selected methionine-rich model peptides, Ac-MMMMPMTFK-NH2 (P1) and Ac-MGMSYMDSK-NH2 (P2), shows that the native copper complex, after sequential loss of phosphines, induces the formation of [Cu(P1)(thp)](+) and [Cu(P1/P2)](+) adducts reasonably by inclusion of the Cu(I) ion in the peptide framework. Collisionally induced fragmentations (MS(n)) of [Cu(P1/P2)](+) give evidence that the metal is coordinated by the thioether-S of two adjacent methionine residues. Interaction of the same peptides with the isostructural complex [Ag(thp)4](+) or AgNO3 yields similar experimental evidence, leading to [Ag(P1/P2)](+).CONCLUSIONS:
Methionine sequences incorporated in model peptides are crucial for the recruitment of copper from CP. Such a metal-peptide interaction does not take place when methionine-free Ac-NleGNleSYNleDSK-NH2 (P3) is utilized. A mechanism for tumor cell internalization of CP involving (i) chemically driven sequential loss of phosphines from the native tetrahedral complex, followed by (ii) transfer of Cu(I) to the methionine-rich sequences typical of the hCtr1 transporter, is proposed.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Peptídeos
/
Fosfinas
/
Cobre
/
Proteínas de Transporte de Cátions
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Complexos de Coordenação
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Antineoplásicos
Limite:
Humans
Idioma:
En
Revista:
Rapid Commun Mass Spectrom
Ano de publicação:
2015
Tipo de documento:
Article