Cover Picture: Proteomics 3'10

Cress caps: Who's in command of what?

Common garden cress (Lepidium sativum) is a reasonably close kin to Arabidopsis thaliana, close enough to serve as a large-scale (20×) germination model, readily dissected to study biological processes genetically defined by the genomic sequence of A. thaliana. Müller et al. set out to explore the inner secrets of germination and seedling establishment using complementary features of the two plants. The two-step germination procedure begins with the rupture of the maternal testa, which reveals the endosperm cap that covered the radicle. The second step is the rupture of the endosperm cap by the radicle. Proteomic evaluation of the process revealed that the endosperm cap is not a food storage organ but a regulatory structure, dealing with stress and heat shock proteins, antioxidants, gluconeogenesis and glycolysis.

Müller, K. et al., Proteomics 2010, 10, 406–416.

Protein purification faces a mesoporous age: Personalized protein–peptide fractionation

A chronic researcher complaint about mass spectrometric analysis of bodily fluids is the limited range of concentrations that can be handled. “All they want is 10 orders of magnitude.” Would it be ok if they were served up in segments? Bouamrani et al. use mesoporous silica chips to fractionate plasma peptides and proteins into groups by size, physical and chemical characteristics. These chips have pore size ranges determined by tri-block copolymers. A mix of silica sol-gel and selected organic block copolymer is spun onto the surface of a silicon wafer. After a series of heating and washing steps, the organic copolymer is removed, leaving pores of a specified size range that can retain and store compatible peptides and proteins. For this proof of principle test, 26 standard peptides and proteins were diluted into serum. Neurotensin could be detected at 2 ng/mL in serum.

Bouamrani, A. et al., Proteomics 2010, 10, 496–505.

Face to face – Serum versus plasma, marker versus marker

Let's face it – we all run into situations we're not quite prepared for, otherwise we wouldn't have “reality” television programs. A situation proteomic researchers encounter when working with blood samples is the choice of extracting markers from serum or plasma. Schwenk et al. explored the differences in protein and peptide intensity profiles for markers extracted from plasma and serum using magnetic antibody bead arrays. Plasma and serum were identical for 79% of antibodies by this assay, but these were not identical faces – they could be grouped by donor-specific and sample-type subgroups.

Schwenk, J. M. et al. Proteomics 2010, 10, 532–540.

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