Uso de espectrometria de massas e mobilidade iônica na caracterização de peptídeos provenientes de experimentos de ligação cruzada / Mass spectrometry and ion mobility in the characterization and of peptides from protein cross-linking experiments

AUTOR(ES)

Luiz Fernando Arruda Santos

FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

10/03/2011

RESUMO

There are several advantages associated with the use of mass spectrometry (MS) applied to structural studies of proteins, such as unlimited mass of target protein or protein complex, very low time and sample consumption, ease of manipulation and interpretation of the data obtained. In chemical cross-linking coupled to MS, bifunctional reagents (cross-linkers, XL) are used to generate covalent bonds between the side chains of specific residues (usually lysine) and the distance constraints obtained are then used to model the structure of the protein and reveal interacting regions in the case of protein complexes. After enzymatic digestion, three types of peptides modified by the XL can be generated: intramolecular cross-linked, in which the cross-linker is linked to two residues of the same peptide; intermolecular cross-linked, when the reagent connects two peptides; and ¿dead-end¿, that occurs when the cross-linker is bound to only one residue and the other side is usually hydrolyzed. The critical step in a cross-linking experiment is the correct attribution and identification of the modified peptides, which is in turn based on the fragmentation of such species. So, the main focus of this work is to perform fragmentation studies of cross-linked peptides and rationalize fragmentation models to aid in the correct identification and attribution of modified peptides. In our studies we verified a fragmentation pattern of modified peptides, as well as diagnostic fragment ions, able to help in the identification of cross-linked peptides. Studies of ion mobility (IMS) coupled to mass spectrometry (IMMS) to analyze cross-linked peptides were also performed. It was possible to separate dead-end isomers and it was verified that linear and modified peptides, of similar m/z have similar collision cross-section.

ASSUNTO(S)

espectrometria de massa mobilidade ionica ligação cruzada mass spectrometry ion mobility cross-linking

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