scholarly journals Streamlined microfluidic analysis of phosphopeptides using stable isotope‐labeled synthetic peptides and MRM‐MS detection

2018 ◽  
Vol 39 (24) ◽  
pp. 3171-3184 ◽  
Author(s):  
Jingren Deng ◽  
Fumio Ikenishi ◽  
Nicole Smith ◽  
Iulia M. Lazar
Keyword(s):  
Stable Isotope ◽  
Synthetic Peptides ◽  
Ms Detection ◽  
Microfluidic Analysis

scholarly journals Evaluation of a Stable Isotope-Based Direct Quantification Method for Dicamba Analysis from Air and Water Using Single-Quadrupole LC–MS

Molecules ◽  
2020 ◽  
Vol 25 (16) ◽  
pp. 3649 ◽  
Author(s):  
Manoj Ghaste ◽  
Nicholas C. Hayden ◽  
Matthew J. Osterholt ◽  
Julie Young ◽  
Bryan Young ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Water Samples ◽  
Detection Method ◽  
Matrix Effects ◽  
Solid Phase ◽  
Internal Standard ◽  
Sample Collection ◽  
Selected Ion Monitoring ◽  
Ms Detection ◽  
Direct Quantification

Dicamba is a moderately volatile herbicide used for post-emergent control of broadleaf weeds in corn, soybean, and a number of other crops. With increased use of dicamba due to the release of dicamba-resistant cotton and soybean varieties, growing controversy over the effects of spray drift and volatilization on non-target crops has increased the need for quantifying dicamba collected from water and air sampling. Therefore, this study was designed to evaluate stable isotope-based direct quantification of dicamba from air and water samples using single-quadrupole liquid chromatography–mass spectrometry (LC–MS). The sample preparation protocols developed in this study utilize a simple solid-phase extraction (SPE) protocol for water samples and a single-step concentration protocol for air samples. The LC–MS detection method achieves sensitive detection of dicamba based on selected ion monitoring (SIM) of precursor and fragment ions and relies on the use of an isotopically labeled internal standard (IS) (D3-dicamba), which allows for calculating recoveries and quantification using a relative response factor (RRF). Analyte recoveries of 106–128% from water and 88–124% from air were attained, with limits of detection (LODs) of 0.1 ng mL−1 and 1 ng mL−1, respectively. The LC–MS detection method does not require sample pretreatment such as ion-pairing or derivatization to achieve sensitivity. Moreover, this study reveals matrix effects associated with sorbent resin used in air sample collection and demonstrates how the use of an isotopically labeled IS with RRF-based analysis can account for ion suppression. The LC–MS method is easily transferrable and offers a robust alternative to methods relying on more expensive tandem LC–MS/MS-based options.

scholarly journals Light contamination in stable isotope-labelled internal peptide standards is frequent and a potential source of false discovery and quantitation error in proteomics

2021 ◽  
Author(s):  
Mogjiborahman Salek ◽  
Jonas D Foerster ◽  
Wolf-Dieter Lehmann ◽  
Angelika B Riemer
Keyword(s):  
Mass Spectrometry ◽  
Stable Isotope ◽  
Biological Samples ◽  
Synthetic Peptides ◽  
Isotopic Enrichment ◽  
Internal Standards ◽  
False Discovery ◽  
Potential Source ◽  
Internal Peptide ◽  
Detection And Quantification

In mass spectrometry-based proteomics, heavy internal standards are used to validate target peptide detections and to calibrate peptide quantification. Here we report light contamination present in heavy labelled synthetic peptides of high isotopic enrichment. Application of such peptides as assay-internal standards potentially compromises the detection and quantification especially of low abundant cellular peptides. Therefore, it is important to adopt guidelines to prevent false-positive identifications of endogenous light peptides as well as errors in their quantification from biological samples.

Vitamin A Value of Plant Food Provitamin A - Evaluated by the Stable Isotope Technologies

2014 ◽  
Vol 84 (Supplement 1) ◽  
pp. 25-29 ◽  
Author(s):  
Guangwen Tang
Keyword(s):  
Stable Isotope ◽  
Vitamin A ◽  
Provitamin A ◽  
Animal Origin ◽  
Plant Food ◽  
Plant Foods ◽  
A Value ◽  
Provitamin A Carotenoids ◽  
Β Carotene

Humans need vitamin A and obtain essential vitamin A by conversion of plant foods rich in provitamin A and/or absorption of preformed vitamin A from foods of animal origin. The determination of the vitamin A value of plant foods rich in provitamin A is important but has challenges. The aim of this paper is to review the progress over last 80 years following the discovery on the conversion of β-carotene to vitamin A and the various techniques including stable isotope technologies that have been developed to determine vitamin A values of plant provitamin A (mainly β-carotene). These include applications from using radioactive β-carotene and vitamin A, depletion-repletion with vitamin A and β-carotene, and measuring postprandial chylomicron fractions after feeding a β-carotene rich diet, to using stable isotopes as tracers to follow the absorption and conversion of plant food provitamin A carotenoids (mainly β-carotene) in humans. These approaches have greatly promoted our understanding of the absorption and conversion of β-carotene to vitamin A. Stable isotope labeled plant foods are useful for determining the overall bioavailability of provitamin A carotenoids from specific foods. Locally obtained plant foods can provide vitamin A and prevent deficiency of vitamin A, a remaining worldwide concern.

Stable isotope metabolic labeling of a mouse model reveals synaptic biomarkers for anxiety disorders

2009 ◽  
Vol 42 (05) ◽  
Author(s):  
MD Filiou ◽  
YY Zhang ◽  
B Bisle ◽  
E Frank ◽  
MS Kessler ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Mouse Model ◽  
Anxiety Disorders ◽  
Metabolic Labeling

Ristocetin and Botrocetin Involve Two Distinct Domains of von Willebrand Factor for Binding to Platelet Membrane Glycoprotein lb

1990 ◽  
Vol 64 (02) ◽  
pp. 326-332 ◽  
Author(s):  
J P Girma ◽  
Y Takahashi ◽  
A Yoshioka ◽  
J Diaz ◽  
D Meyer
Keyword(s):  
Von Willebrand Factor ◽  
Synthetic Peptides ◽  
Competitive Inhibition ◽  
Final Concentration ◽  
Binding Domain ◽  
Platelet Membrane ◽  
Platelet Glycoprotein ◽  
Membrane Glycoprotein ◽  
Von Willebrand ◽  
Willebrand Factor

SummaryWe have evidence that ristocetin and botrocetin mediate binding of von Willebrand Factor (vWF) to platelet glycoprotein lb (GPIb) through two distinct domains on the vWF molecule. This was established by using monoclonal antibodies (MAbs) to vWF and synthetic peptides derived from the sequence of vWF. MAb 322 and MAb NMC/vW 4 both recognize native vWF as well as fragments containing the GPIb-binding domain of vWF, obtained with the following enzymes: trypsin (116 kDa), V-8 pro tease (Spill, 320 kDa) and V-8 protease plus subtilisin (33-28 kDa). Nevertheless, the lack of reciprocal displacement between the two MAbs in experiments of competitive inhibition for binding to vWF demonstrate that their respective epitopes are separate. Both MAbs inhibit 125I-vWF binding to platelet membrane GPIb and vWF-dependent platelet agglutination induced by ristocetin. However, only MAb NMC/vW4 inhibits these functions in the presence of botrocetin and when ristocetin-induced platelet agglutination is inhibited by MAb 322, botrocetin is still able to restore the agglutination. The involvement of two distinct domains of vWF for binding to GPIb in the presence of ristocetin or botrocetin was confirmed in experiments of binding of 125I-vWF to platelets using as competitor synthetic peptides corresponding to the GPIb binding domain of vWF (Cys 474 to Pro 488 and Ser 692 to Pro 708). At a final concentration of 2.5 mM both peptides inhibit more than 90% of the binding of vWF to ristocetin-treated platelets but are unable to modify this binding in the presence of botrocetin. In conclusion our data suggest that botrocetin and ristocetin involve distinct sites on vWF for binding to GPIb.

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