Dataset Information

Simulated spectral library searching on TripleTOF phosphopeptide datasets

ABSTRACT: Synthetic phosphopeptides and enriched K562 cell phosphopeptides were analyzed using a TripleTOF 6600 mass spectrometer before and after enzymatic dephosphorylation. Dephosphorylated peptides identified by X!Tandem database searching were subjected to spectral simulation of all possible single phosphorylations using SimPhospho software. Phosphopeptides were identified and localized by SpectraST searching against a library of the simulated spectra, and also by MaxQuant database searching.

ORGANISM(S): Homo Sapiens (human)

SUBMITTER: Susumu Y. Imanishi

PROVIDER: PXD012433 | JPOST Repository | Tue Dec 03 00:00:00 GMT 2019

REPOSITORIES: jPOST

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Publications

Optimization of TripleTOF spectral simulation and library searching for confident localization of phosphorylation sites.

Takai Ayano A Tsubosaka Tomoya T Hirano Yasuhiro Y Hayakawa Naoki N Tani Fumitaka F Haapaniemi Pekka P Suni Veronika V Imanishi Susumu Y SY

PloS one 20191202 12

Tandem mass spectrometry (MS/MS) has been used in analysis of proteins and their post-translational modifications. A recently developed data analysis method, which simulates MS/MS spectra of phosphopeptides and performs spectral library searching using SpectraST, facilitates confident localization of phosphorylation sites. However, its performance has been evaluated only on MS/MS spectra acquired using Orbitrap HCD mass spectrometers so far. In this study, we have investigated whether this appro ...[more]

PMID: 31790495

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Project description:Abstract: Despite recent advances in instrumentation and analytical strategies for identification and quantitation of protein phosphorylation, methodologies to enrich the heterogeneous types of phosphopeptides are critical towards comprehensive mapping of the under-explored phosphoproteome. Taking advantage of the distinctive binding affinity of Ga3+ and Fe3+ towards phosphopeptides, we designed a tip-based metal-directed immobilized metal ion affinity (MD-IMAC) chromatography for sequential enrichment of phosphopeptides. On the analysis of Raji B cell, this sequential Ga3+-Fe3+-IMAC strategy demonstrated 1.5-3.5 fold superior phosphoproteomic coverage compared to the single IMAC (Fe3+, Ti4+, Ga3+ and Al3+). In addition, as high as 92% among the 6283 phosphopeptides was uniquely enriched by either 1st Ga3+-IMAC fraction (41%) or 2nd Fe3+-IMAC fraction (51%). The complementary property of Ga3+ and Fe3+ was further shown on the exclusively superior efficiency to enriched almost all the 1214 multiply phosphorylated peptides (99.4%) by 1st Ga3+-IMAC, while as low as 10% of 5069 monophosphorylated phosphopeptides was commonly enriched by both fractions. Application of our sequential Ga3+-Fe3+-IMAC approach to a human lung cancer tissue allowed the identification of 2560 unique phosphopeptides with only 8% overlapping. The fractionation ability was shown not only on the mono phosphopeptides and multiply phosphopeptides but also on the basic and acidic phosphopeptides; acidiphilic phosphorylation sites were predominately present in 1st Ga3+-IMAC (72%) and 85% Pro-directed and 79% basophilic phosphorylation sites were enriched by 2nd Fe3+-IMAC. Most interestingly, this strategy complementarily mapped different kinase substrate on the protein as well as site levels in multiple cellular pathways related to cancer invasion and metastasis of lung cancer ., Given the demonstrated fractionation ability, reproducibility, sensitivity and ease of tip preparation, we hope that this Ga3+-Fe3+-IMAC allow more comprehensive characterization of phosphoproteome in vitro and in vivo. Database search: The raw MS/MS data obtained by TripleTOF 5600 were processed using AB_SCIEX MS Data Converter with default parameters. All MS/MS files were analyzed using Mascot (Matrix Science, London, UK; version 2.3) against the SwissPort database (version 57.8) with the following constraints: an allowance for tryptic peptides of up to two missed cleavage sites, a fragment ion mass tolerance of 0.05 Da, and a parent ion tolerance of 10 ppm. Phosphorylation (S, T, Y) and oxidation (M) were selected as variable modifications. Searching on a randomized decoy database created by Mascot was required to evaluate the false discovery rate associated with protein identification. The false discovery rates with a Mascot score (p< 0.05) ranged between 0% and 1% in this study.

Dataset Information

Simulated spectral library searching on TripleTOF phosphopeptide datasets

Publications

Optimization of TripleTOF spectral simulation and library searching for confident localization of phosphorylation sites.

Similar Datasets

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