Profiling of rat plasma by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry, a novel tool for biomarker discovery in nutrition research

The recent development of high-throughput proteomic technologies has given us new methods to analyze how an organism responds to changes in its nutritional environment. The analysis of plasma samples by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI–TOF–MS) was investigated as a novel approach to the identification of new biomarkers of nutrient status. Pre-fractionation of rat plasma by anion-exchange chromatography in 96-well filter plates markedly increased the total number of unique peptides and proteins that could be observed in SELDI–TOF mass spectra. Replicate fractionations generated nearly identical pH fractions, not only in terms of peptide and protein composition but also in respect to the ion signal intensity of replicate SELDI–TOF mass spectra. The feasibility of this approach was tested with samples from retinol-sufficient and retinol-deficient rats. The comparative analysis revealed reduced levels of three proteins with molecular masses between 10 000 and 20 000 in plasma of retinol-deficient rats. These results demonstrate that plasma profiling by anion-exchange fractionation and SELDI–TOF–MS may be a promising surveillance tool to detect changes in nutritional status and whole body physiology.