Protein phosphorylation stoichiometry by simultaneous ICP-QMS determination of phosphorus and sulfur oxide ions: a multivariate optimization of plasma operating conditions.

摘要: Abstract Molecular mass spectrometry (MS) analysis of protein phosphorylation is partially limited by the molecular specie specificity analytical responses that might impair both qualitative and quantitative performances. Elemental MS, such as inductively coupled plasma (ICP-MS) can overcome these drawbacks; in fact, performance theoretically independent structure a target analyte naturally containing elements interest. Nevertheless, isobaric interferences derived from sample matrix laboratory environment hinder determination phosphorus (P) sulfur (S) 31P+ 32S+ quadrupole (ICP-QMS) under standard conditions. These may be quantifying P S oxide ions 31P16O+ 32S16O+, respectively. In this study, we present systematic investigation on effect instrumental conditions ion design experiment approach for simultaneous ICP-QMS (31P16O+ respectively) samples without use dynamic reaction, collision reaction cells or pre-addition oxygen reactant gas torch. The proposed method was evaluated terms limit detection, quantification, linearity, repeatability, trueness. Moreover, detection quantification capabilities optimized were compared to mode 34S+. Spectral non-spectral affecting 31P+, 32S16O+ also studied. suitability inorganic elemental standards proteins assessed. applied quantify stoichiometry commercially available caseins (bovine β-casein, native dephosphorylated α-casein) results confirmed Matrix Assisted Laser Desorption Ionization Time Flight MS analysis. We demonstrate ICP-QMS, ions, able accurately calculate degree β-casein α-casein detect specific partial enzymatic dephosphorylation. collected lead further development interfaces studies proteomics investigations.