title: Evaluation of protease inhibitors containing tubes for MS-based plasma peptide profiling studies.
abstract: BACKGROUND
  Peptide profiling of biological fluids is a promising tool for biomarker discovery. Blood is an ideal entity for proteomic studies but it is subjected to a proteolytic activity that sets up just at the moment of phlebotomy. Intending to prevent this proteolytic activity, tubes containing protease inhibitors (PI) have been developed. In this study, we evaluated the effect on plasma peptide profile of using tubes containing PI and the evolution of this effect over time.
  
  
  METHODS
  Blood samples from ten subjects were drawn into conventional tubes containing ethylenediaminetetraacetic acid (EDTA) and tubes containing PI. Samples were processed at time "zero" and after 1, 2, 4, and 8 hr. Plasma peptide profiles were analyzed by magnetic bead based technology coupled to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry readout.
  
  
  RESULTS
  When comparing plasma peptide profile of blood samples collected into tubes containing PI with samples collected into conventional EDTA tubes, differences in the area of 13 peaks were detected at time "zero"; after 8 hr these differences tended to disappear. Moreover, bradykinin and C3- and C4-derived peptides were produced promptly after blood extraction when samples were collected into conventional EDTA tubes, and the use of PI prevented their generation.
  
  
  CONCLUSIONS
  Considering that time taken to process blood samples affects their peptide profile and a decrease in PI's effect occurs over time, it may be concluded that the use of tubes containing PI for blood collection may be advantageous in the context of research, but may have some limitations regarding clinical practice.
authors.affiliation: Department of Nephrology, Hospital Universitari Germans Trias i Pujol, Universitat Autònoma de Barcelona, Badalona, Spain; Laboratory of Experimental Nephrology, Fundació Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol, Universitat Autònoma de Barcelona, Badalona, Spain.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Pérez
authors.forename: Javier
authors.initials: J
authors.lastname: Juega-Mariño
authors.forename: Anna
authors.initials: A
authors.lastname: Bonjoch
authors.forename: Eugenia
authors.initials: E
authors.lastname: Negredo
authors.forename: Bonaventura
authors.initials: B
authors.lastname: Clotet
authors.forename: Ramón
authors.initials: R
authors.lastname: Romero
authors.forename: Josep
authors.initials: J
authors.lastname: Bonet
mesh_terms: D000328:Adult; D001800:Blood Specimen Collection / Q000295:instrumentation*; D065096:Calcium Chelating Agents / Q000494:pharmacology; D004492:Edetic Acid / Q000494:pharmacology; D005260:Female; D006801:Humans; D008297:Male; D013058:Mass Spectrometry; D008875:Middle Aged; D010455:Peptides / Q000032:analysis* / Q000187:drug effects; D010949:Plasma / Q000737:chemistry* / Q000187:drug effects*; D011446:Prospective Studies; D011480:Protease Inhibitors / Q000494:pharmacology*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D018709:Statistics, Nonparametric; D013997:Time Factors
chemical_list: D065096:Calcium Chelating Agents; D010455:Peptides; D011480:Protease Inhibitors; D004492:Edetic Acid
keywords: MALDI-TOF MS; collection tubes; magnetic beads; preanalytical variability; proteomics