Electron Capture vs Transfer Dissociation for Site Determination of Tryptic Peptide Tyrosine Sulfation: Direct Detection of Fibrinogen Sulfation Sites and Identification of Novel Isobaric Interferences.
J Proteome Res
; 23(7): 2386-2396, 2024 Jul 05.
Article
em En
| MEDLINE
| ID: mdl-38900499
ABSTRACT
Tyrosine sulfation, an understudied but crucial post-translational modification, cannot be directly detected in conventional nanoflow liquid chromatography-tandem mass spectrometry (nanoLC-MS/MS) due to the extreme sulfate lability. Here, we report the detection of sulfate-retaining fragments from LC-electron capture dissociation (ECD) and nanoLC-electron transfer higher energy collision dissociation (EThcD). Sulfopeptide candidates were identified by Proteome Discoverer and MSFragger analysis of nanoLC-HCD MS/MS data and added to inclusion lists for LC-ECD or nanoLC-EThcD MS/MS. When this approach failed, targeted LC-ECD with fixed m/z isolation windows was performed. For the plasma protein fibrinogen, the known pyroglutamylated sulfopeptide QFPTDYDEGQDDRPK from the beta chain N-terminus was identified despite a complete lack of sulfate-containing fragment ions. The peptide QVGVEHHVEIEYD from the gamma-B chain C-terminus was also identified as sulfated or phosphorylated. This sulfopeptide is not annotated in Uniprot but was previously reported. MSFragger further identified a cysteine-containing peptide from the middle of the gamma chain as sulfated and deamidated. NanoLC-EThcD and LC-ECD MS/MS confirmed the two former sulfopeptides via sulfate-retaining fragment ions, whereas an unexpected fragmentation pattern was observed for the third sulfopeptide candidate. Manual interpretation of the LC-ECD spectrum revealed two additional isobaric identifications a trisulfide-linked cysteinyl-glycine or a carbamidomethyl-dithiothreiotol covalent adduct. Synthesis of such adducts confirmed the latter identity.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Tirosina
/
Fibrinogênio
/
Espectrometria de Massas em Tandem
Limite:
Humans
Idioma:
En
Revista:
J Proteome Res
Assunto da revista:
BIOQUIMICA
Ano de publicação:
2024
Tipo de documento:
Article
País de afiliação:
Estados Unidos