An ICP-MS-assisted proteomics approach allowed for the identification of 17 selenium-containing proteins present in selenium-rich yeast, out of which 12 are reported for the first time.
Background:
Selenium is an essentiual element for animals and humans, but its physiological nature is ambivalent. It can cause disease by deficiency, but it is toxic at levels less than one order of magnitude above those rquired for health. Since its biological activity heavily depends on the chemical form present, the need for analytical speciation is evident.
Especially the indication of the putative role of selenium in the prevention of some forms of cancer has found considerable attention and has triggered off the proliferation of food supplements fortified with this element. While there is a general agreement that organic forms of selenium are prefered for supplementation, the species being present in fortified-yeast have only partly been identified.
The new study:
A group of researchers from the University of Pau (France) developed an ICP-MS-assisted proteomics approach for the characterization of Se-containing proteins in selenium-rich yeast.
Starting point is an ultrasound probe-assisted leaching of a yeast sample with 8 M urea and
4% CHAPS {3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate}. The extraction and following purification were optimized for highest selenium and protein extraction yield. Extracted proteins were separated by 2D gel electrophoresis. Fourteen spots containing selenium were located by laser ablation-ICP-MS, excised and analysed by nanoHPLC with the consecutive ICP-MS and electrospray Q-TOF MS/MS detection. Using the combined elemental and molecular information, the method allowed a successful identification of 17 selenium-containing proteins:
- MMF1 protein *
- Enolase 1
- Enolase 2
- Eukaryotic translation initiation factor 5A-2 *
- Heat shock protein SSA1
- Phosphoglycerate kinase *
- Peptidyl-prolyl cis-trans isomerase *
- Glyceraldehyde-3-phosphate dehydrogenase 3 *
- 13.2 kDa protein
- Phosphoglycerate mutase 1 *
- Adenylate kinase cytosolic *
- Elongation factor 1-beta *
- Thioredoxin II *
- Malate dehydrogenase *
- 12 kDa heat shock protein
- 10 kDa heat shock protein *
- Superoxide dismutase *
* identified for the first time
The success of the approach developed was critically dependent on protein extraction yield and purification quality, and the reproducibility of gel electrophoresis and nanoHPLC
separations. Highly sensitive selenium-specific detection by ICP-MS was the key to accessing low-abundance, selenium-containing proteins.
The new study
Laure Tastet,
Dirk Schaumlöffel,
Ryszard Lobinski, ICP-MS-assisted proteomics approach to the identification of selenium-containing proteins in selenium-rich yeast, J. Anal. At. Spectrom., 23/3 (2008) 309-317.
DOI: 10.1039/b713805a Related studies Gavin L. Sacks, Louis A. Derry, J. Thomas Brenna,
Elemental Speciation by Parallel Elemental and Molecular Mass Spectrometry and Peak Profile Matching, Anal. Chem., 78/24 (2006) 8445-8455.
DOI: 10.1021/ac0612170 Laure Tastet,
Dirk Schaumlöffel,
Brice Bouyssiere,
Ryszard Lobinski,
Capillary HPLC-ICP MS mapping of selenocompounds in spots obtained from the 2-D gel electrophoresis of the water-soluble protein fraction of selenized yeast, Anal. Bioanal. Chem., 385/5 (2006) 948-953.
DOI: 10.1007/s00216-006-0482-6 Juan F. García-Reyes, Mihaly Dernovics,
Pierre Giusti, Ryszard Lobinski,
Identification of new selenium non-peptide species in selenized yeast by nanoHPLC electrospray Q/time-of-flight-MS/MS, J. Anal. At. Spectrom., 21/7 (2006) 655-665.
DOI: 10.1039/b518297b G.N. Schrauzer, Selenium yeast:
Composition, quality, analysis, and safety, Pure Appl. Chem., 78/1 (2006) 105-109.
DOI: 10.1351/pac200678010105 Heidi Goenaga-Infante, Ruth Hearn, Tim Catterick,
Current mass spectrometry strategies for selenium speciation in dietary sources of high-selenium, Anal. Bioanal. Chem., 382/4 (2005) 957-967.
DOI: 10.1007/s00216-005-3177-5
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