Capillary HPLC-ICPMS and tyrosine iodination for the absolute quantification of peptides using generic standards.

The validity of using tyrosine iodination chemistry for the absolute and generic quantification of peptides by capillary high-performance liquid chromatography (capHPLC) coupled to inductively coupled plasma mass spectrometry (ICPMS) is investigated in detail. In this approach, two iodine atoms are specifically bioconjugated to the meta positions of the aromatic ring of every tyrosine residue. Characterization studies by capHPLC with parallel ICPMS and electrospray ionization tandem mass spectrometry (ESIMS/MS) detection clearly showed that such labeling iodination reaction affords one to obtain most accurate peptide determinations (after translation of the picomoles of iodine, quantified by ICPMS in each chromatographic peak, into picomoles of the corresponding labeled peptide).

Element mass spectrometry as a tool for high-resolution temporal dynamics investigations of peptide phosphorylation.

The great potential of capillary HPLC (capHPLC) coupled to element mass spectrometry (ICPMS) to study peptide phosphorylation dynamics was evaluated, and the high precision associated with the absolute quantification of the phosphopeptides provided the most detailed phosphorylation time profile ever reported.

Absolute and site-specific quantification of protein phosphorylation using integrated elemental and molecular mass spectrometry: its potential to assess phosphopeptide enrichment procedures.

The validity of using elemental phosphorus standards to accurately and precisely quantify phosphopeptides by capillary HPLC (capHPLC) coupled to ICP-collison cell-MS is investigated in detail. Operating requirements to maintain stable (31)P sensitivity along the reversed-phase gradient are described. Specifically, the use of an optimum postcolumn makeup flow with a defined acetonitrile content turned out to be necessary to buffer the acetonitrile variation of the capillary chromatographic eluent and ensure plasma stability.

Study of phytochelatins and other related thiols as complexing biomolecules of As and Cd in wild type and genetically modified Brassica juncea plants.

The accumulation of As and Cd in Brassica juncea plants and the formation of complexes of these elements with bioligands such as glutathione and/or phytochelatins (PCs) is studied. The genetic manipulation of these plants to induce higher As and Cd accumulation has been achieved by overexpressing the genes encoding for gamma-glutamyl cysteine synthetase (gamma-ECS) and glutathione synthetase (GS). These two enzymes are responsible for glutathione (GSH) formation in plants, which is the first step in the production of PCs.