title: Isotope labeled internal standards (ILIS) as a basis for quality control in clinical studies using plasma samples.
abstract: For clinical proteomic studies, the quality of the biofluid samples such as human blood plasma is extremely important. In this study we have investigated the stability of human plasma samples by spiking stable isotope-labeled peptides into the plasma and monitoring their degradation under different storage conditions. FPA-1, C4A and C3f were synthesized with isotopically labeled amino acids, and used as reference peptides. The mixture of internal calibrants was spiked into plasma at the starting point of investigation, mimicking the time of collection for future biobanking efforts, and their qualitative and quantitative changes were analyzed over time by using both MALDI-MS (LTQ Orbitrap XL) and nanoLC-ESI-MS (LTQ XL ETD). We have found that all three synthetic peptides were stable in plasma at -20 and -80 degrees C during the examined 2-month period. However, different proteolytic degradation profiles of the peptides were observed at room temperature. We anticipate that the use of these isotope-labeled peptides as internal standards (ILIS) provides a quality control for long-term storage and proteomic plasma analysis.
authors.affiliation: Clinical Protein Science & Imaging, Dept. of Measurement Technology and Industrial Electrical Engineering, Lund University, BMC C13, SE-221 84 Lund, Sweden. melinda.rezeli@elmat.lth.se
authors.forename: Melinda
authors.initials: M
authors.lastname: Rezeli
authors.forename: Akos
authors.initials: A
authors.lastname: Végvári
authors.forename: György
authors.initials: G
authors.lastname: Marko-Varga
authors.forename: Thomas
authors.initials: T
authors.lastname: Laurell
mesh_terms: D035843:Biomedical Research / Q000379:methods / Q000592:standards; D001798:Blood Proteins / Q000737:chemistry*; D002138:Calibration; D006801:Humans; D007553:Isotope Labeling / Q000379:methods; D007554:Isotopes / Q000737:chemistry; D010455:Peptides / Q000737:chemistry*; D010949:Plasma / Q000378:metabolism; D020543:Proteome / Q000737:chemistry*; D040901:Proteomics / Q000379:methods* / Q000592:standards; D011786:Quality Control; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods; D013696:Temperature; D013997:Time Factors
chemical_list: D001798:Blood Proteins; D007554:Isotopes; D010455:Peptides; D020543:Proteome