title: Quantitative analysis of proteins via sulfur determination by HPLC coupled to isotope dilution ICPMS with a hexapole collision cell.
abstract: Quantitative analysis of proteins is an essential part and also constitutes a major challenge in modern proteomics. Quantification of proteins by inductively coupled plasma mass spectrometry (ICPMS) offers an alternative method for quantitative proteomics. In this study, we developed a method of absolute quantification of proteins via sulfur by size exclusion chromatography (SEC) coupled to ICPMS with a collision cell (ICP-CC-MS) and postcolumn isotope dilution. Bovine serum albumin (BSA), superoxide dismutase (SOD), and metallothionein-II (MT-II) served as model proteins. Enriched 34S, 65Cu, and 67Zn isotopic solutions were continuously mixed with the eluate from the SEC. Oxygen was added as a reactive gas into the collision cell where sulfur reacts with oxygen to form sulfur-oxygen ion, the ratio of 32S16O(+)/34S16O(+) thus representing 32S(+)/34S(+). The absolute quantity of proteins could be calculated by the isotopic dilution equation and the content of sulfur in the proteins. The detection limits for BSA, SOD, and MT-II are 8, 31, and 15 pmol, respectively. The relative standard deviations for the proteins are less than 3%. The ratios of S/Cu and S/Zn in the proteins were also determined. The quantitative method was validated by comparing with gravimetric results.
authors.affiliation: Key Laboratory of Nuclear Analytical Techniques and Laboratory for Bio-Environmental Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China.
authors.forename: Meng
authors.initials: M
authors.lastname: Wang
authors.forename: Weiyue
authors.initials: W
authors.lastname: Feng
authors.forename: Wenwei
authors.initials: W
authors.lastname: Lu
authors.forename: Bai
authors.initials: B
authors.lastname: Li
authors.forename: Bing
authors.initials: B
authors.lastname: Wang
authors.forename: Motao
authors.initials: M
authors.lastname: Zhu
authors.forename: Yun
authors.initials: Y
authors.lastname: Wang
authors.forename: Hui
authors.initials: H
authors.lastname: Yuan
authors.forename: Yuliang
authors.initials: Y
authors.lastname: Zhao
authors.forename: Zhifang
authors.initials: Z
authors.lastname: Chai
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D007554:Isotopes; D013058:Mass Spectrometry / Q000379:methods*; D011506:Proteins / Q000032:analysis*; D015203:Reproducibility of Results; D013455:Sulfur / Q000032:analysis*
chemical_list: D007554:Isotopes; D011506:Proteins; D013455:Sulfur