ArticleRapid communications in mass spectrometry : RCM2014
Studies on quantitative phosphopeptide analysis by matrix-assisted laser desorption/ionization mass spectrometry without label, chromatography or calibration curves.
Article in Rapid communications in mass spectrometry : RCM, 2014. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 3 papers.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
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Who cites it
3 citing papers in PubMed, 9 citations in OpenAlex.
- Absolute Quantitation of Phosphopeptides and Glycopeptides Using Coulometric Mass Spectrometry.ACS measurement science au · 2025Article
- Cell-Penetrating d-Peptides Retain Antisense Morpholino Oligomer Delivery Activity.ACS bio & med chem Au · 2022Article
- Quantification of desmosine and isodesmosine using MALDI-ion trap tandem mass spectrometry.Analytical and bioanalytical chemistry · 2018Article
Corrections and comments
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Authors and funding
11 authors at 5 institutions in 1 country.
Funding
Abstract
rationaleMatrix-assisted laser desorption/ionization (MALDI) mass spectrometry combined with isotope labeling methods are effective for protein and peptide quantification, but limited in their multiplexing capacity, cost-effectiveness and dynamic range. This study investigates MALDI-MS-based quantification of peptide phosphorylation without labeling, and aims to overcome the shot-to-shot variability of MALDI using a mathematical transformation and extended data acquisition times.
methodsA linear relationship between the reciprocal of phosphopeptide mole fraction and the reciprocal of phosphorylated-to-unphosphorylated signal ratio is derived, and evaluated experimentally using three separate phosphopeptide systems containing phosphorylated serine, threonine and tyrosine residues: mixtures of phosphopeptide and its des-phospho-analog with known stoichiometry measured by vacuum MALDI-linear ion trap mass spectrometry and fit to the linear model. The model is validated for quantifying in vitro phosphorylation assays with inhibition studies on Cdk2/cyclinA.
resultsDynamic range of picomoles to femtomoles, good accuracy (deviations of 1.5-3.0% from expected values) and reproducibility (relative standard deviation (RSD) = 4.3-6.3%) are achieved. Inhibition of cyclin-dependent kinase phosphorylation by the classical inhibitors olomoucine and r-roscovitine was evaluated and IC50 values found to be in agreement with reported literature values. These results, achieved with single-point calibration, without isotope or chromatography, compare favorably to those arrived at using isotope dilution (p > 0.5 for accuracy).
conclusionsThe mathematical relationship derived here can be applied to a method that we term Double Reciprocal Isotope-free Phosphopeptide Quantification (DRIP-Q), as a strategy for quantification of in vitro phosphorylation assays, the first MALDI-based, isotope- and calibration curve-free method of its type. These results also pave the way for further systematic studies investigating the effect of peptide composition and experimental conditions on quantitative, label-free MALDI.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.