Surfactant-aided Matrix Assisted Laser Desorption/ionization Mass Spectrometry (sa-Maldi Ms)

Download or read book Surfactant-aided Matrix Assisted Laser Desorption/ionization Mass Spectrometry (sa-Maldi Ms) written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is an important tool for high throughput analysis in the field of genome mapping, medical diagnostics and protein identification. Though it is the best option for rapid complex mixture analysis, it does suffer from ion suppression effects, which depend on the type of analytes in the mixture and the sample preparation techniques. The goal of this dissertation is to develop surfactant-aided MALDI-MS (SA-MALDI-MS) for the characterization of complex mixtures and to understand the role of the surfactant in such analyses. Critical micellar concentrations (CMC) of sodium dodecylsulfate (SDS), 0.1%-0.3% w/v, were found to be optimal for SA-MALDI-MS of complex mixtures. The presence of micelles was confirmed by surface tension experiments. To determine the role of these micelles, interactions between SDS and peptides of varying hydrophobicities were studied by fluorescence. Further, SA-MALDI-MS was used in peptide mass fingerprinting, modification mapping and serum profiling experiments to demonstrate the versatility of this technique. Peptide mapping experiments were performed on model proteins using MALDI and SA-MALDI MS. From these experiments it was found that on addition of SDS prior to MALDI analysis there was an increase in the number of tryptic peptides detected thereby improving the total sequence coverage of the analysis. It was found that interactions between peptides and SDS micelles depended on peptide hydrophobicity, sequence, size and charge. In an approach to determine the sites of interactions between MSP and other oxygen-evolving protein complex, chemical protection assays were used to label MSP, and SA-MALDI-MS along with sample fractionation were used to increase sequence coverage from peptide mapping experiments to identify sites of chemical modification. SA-MALDI-MS was also investigated as a sample preparation approach for serum protein profiling. Various clean-up methods were used in conjunction with SDS and other surfactants to study the differences in serum protein profiles. This approach offers the potential for higher throughput sample preparation during protein profiling of biological fluids.