Analysis of complex protein samples is demanding due to the wide dynamic range of expression levels and the limited detection range of technology. Proteomics relies heavily on the development of new fractionation strategies to help reduce complexity, and overcome the technological and biological challenges associated with proteome analysis. Here, the development of a prototype instrument named ??Microflow MF10?? was explored to enrich for particular classes of proteins. The MF10 was found to have a number of advantages over commercially available fractionation systems. Due to the reduced separation electrode distance, fractionation was rapid, occuring within ~0.125 kVH over 2-6 fractions under native conditions but longer under denaturing conditions. As low as 2 ng peptide could be fractionated with recovery for downstream analysis achievable. The ability to alter protein charge by changing the pH (acidic (pI 3.6) to basic environments (pI 10.4)) allows selection of proteins based on charge/mobility, size, shape, buffer ionic strength, pH and field strength. Proteins <10 kDa are also not routinely analysed because current technology is unable to cater for this region of the proteome. Peptide enrichment using the MF10 was achieved using a 7-protein/peptide standard mix (1-25 kDa), to the 1-5 kDa fraction with simultaneous fractionation of the higher mass protein standards. Plasma was also used to enrich for the peptidome (< 5 kDa) in the presence of the proteome. Enrichment of 73 proteins inclusive of 22 proteins in the 1-25 kDa fraction was achieved compared to a total equivalent of 42 proteins from unfractionated plasma. Rare samples (≤ 106 cells) from stem cell populations or derived clinically are challenging due to the absolute limits in protein copy number and abundance. CD34+ haematopoietic stem cells and CD4+/CD8+ T-cells were used to develop fractionation methods and elucidate the cell differentiation process. MF10 fractionation and analysis by SDS-PAGE and LC-MS/MS revealed 24 differentially expressed proteins between the 3 cell populations, which may be involved in cell differentiation. To quantify these expression differences, iTRAQ with 2-D LC-MS/MS was applied. This study has highlighted the challenges associated with samples of limited quantity. It has been successful in understanding the effects of various conditions on the electrophoretic mobility of proteins, which in proteomics, has remained largely unexplored.
| Identifer | oai:union.ndltd.org:ADTP/211584 |
| Date | January 2008 |
| Creators | Ly, Linda, Biotechnology & Biomolecular Sciences, Faculty of Science, UNSW |
| Publisher | Publisher:University of New South Wales. Biotechnology & Biomolecular Sciences |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | http://unsworks.unsw.edu.au/copyright, http://unsworks.unsw.edu.au/copyright |
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