Cover Picture: Proteomics 22/2008

Abstract

AbstractIn this issue of Proteomics you will find the following highlighted articles:Man bites dog! Noise improves signal!Yes, the right kind of noise does improve the signal (by about 10‐fold in the LC/MS case described here). Scheltema et al. used the noise generated by the ions remaining in the sample from the LC step as internal standards to standardize and calibrate the mass spectrum of interest. Given a set of well characterized contaminants at very low, but detectable levels, the researchers were able to appropriately stretch or compress spectra by comparison to a reference spectrum of contaminants expected in a particular sample. The demonstration was performed on a Thermo Fisher LTQ Orbitrap system which, run conventionally, yielded a mass accuracy of 1 to 2 parts per million. When the noise method was applied to the same data, the mass accuracy was 0.21 ppm.Scheltema, R. A. et al., Proteomics 2008, 8, 4647–4656.Rafting down the Melanoma riverWhen the subject is rafts, Mark Twain's story of Tom Sawyer and Huckleberry Finn rafting down the Mississippi comes immediately to mind for most Americans. A raft of interest to life scientists is associated with detergent resistant membranes found in malignant melanoma cell lines. Made of predominantly cholesterol and sphingolipids, the raft and associated proteins have been shown to participate in signal regulation and protein trafficking as well as several diseases. Working from this information, Baruthio et al. have looked at the lipid raft proteome as a function of melanoma malignancy stage using LC‐MS/MS: radial growth phase, (pre‐metastatic); early vertical growth phase, (non‐metastatic); and fully transformed. They found >175 proteins total in all stages, the most abundant was AHNAK, a large membrane protein. Groups of potential stage markers were detected, although with some difficulty in reproducibility of extraction. Functions found included vacuolar ATPases, adhesion molecules, and signaling pathway regulators.Baruthio, F. et al., Proteomics 2008, 8, 4733–4747.Hot peppers maker confusing soupCapsaicin is the naturally occurring compound that gives chili peppers their “heat.” It is also a component of the pepper's arsenal, deterring some types of attacks. Another of its roles is in regulation of programmed cell death, apoptosis: sometimes it promotes it, sometimes it inhibits it and it always seems to involve reactive oxygen species (ROS). To look at its function as a potential anti‐cancer agent, Baek et al. compared its effect on two human cancer cell lines. HepG2, a hepatoblastoma and SK‐N‐SH, a neuroblastoma, were examined for proteomic changes after exposure to capsaicin at various levels and for various times. Both blastomas responded but in markedly different fashions. Apoptosis was induced in both cell lines, but the ROS levels were up in HepG2 and down in SK‐N‐SH. A number of ROS enzymes exhibited anomalous expression level changes, possibly due to the number of enzymes involved.Baek, Y. M. et al., Proteomics 2008, 8, 4748–4767.