A binary matrix for improved detection of phosphopeptides in matrix-assisted laser desorption/ionization mass spectrometry.
Rapid Commun Mass Spectrom
; 23(15): 2264-72, 2009 Aug.
Article
em En
| MEDLINE
| ID: mdl-19551845
ABSTRACT
Application of matrix-assisted laser-desorption/ionization mass spectrometry (MALDI MS) to analysis and characterization of phosphopeptides in peptide mixtures may have a limitation, because of the lower ionizing efficiency of phosphopeptides than nonphosphorylated peptides in MALDI MS. In this work, a binary matrix that consists of two conventional matrices of 3-hydroxypicolinic acid (3-HPA) and alpha-cyano-4-hydroxycinnamic acid (CCA) was tested for phosphopeptide analysis. 3-HPA and CCA were found to be hot matrices, and 3-HPA not as good as CCA and 2,5-dihydroxybenzoic acid (DHB) for peptide analysis. However, the presence of 3-HPA in the CCA solution with a volume ratio of 11 could significantly enhance ion signals for phosphopeptides in both positive-ion and negative-ion detection modes compared with the use of pure CCA or DHB, the most common phosphopeptide matrices. Higher signal intensities of phosphopeptides could be obtained with lower laser power using the binary matrix. Neutral loss of the phosphate group (-80 Da) and phosphoric acid (-98 Da) from the phosphorylated-residue-containing peptide ions with the binary matrix was decreased compared with CCA alone. In addition, since the crystal shape prepared with the binary matrix was more homogeneous than that prepared with DHB, searching for 'sweet' spots can be avoided. The sensitivity to detect singly or doubly phosphorylated peptides in peptide mixtures was higher than that obtained with pure CCA and as good as that obtained using DHB. We also used the binary matrix to detect the in-solution tryptic digest of the crude casein extracted from commercially available low fat milk sample, and found six phosphopeptides to match the digestion products of casein, based on mass-to-charge values and LIFT TOF-TOF spectra.
Texto completo:
1
Temas:
ECOS
/
Aspectos_gerais
Bases de dados:
MEDLINE
Assunto principal:
Fosfopeptídeos
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Ácidos Picolínicos
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Caseínas
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Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz
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Ácidos Cumáricos
Tipo de estudo:
Diagnostic_studies
/
Evaluation_studies
Limite:
Animals
Idioma:
En
Revista:
Rapid Commun Mass Spectrom
Ano de publicação:
2009
Tipo de documento:
Article