Is the mission to identify all the human proteins achievable? —Commenting on the human proteome draft maps

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Heat treatment of small heat shock proteins α-crystallin and Hsp16.3: structural changes vs. chaperone-like activity

Both α-crystallin from bovine eye lens and Hsp16.3 from Mycobacterium tuberculosis are members of the small heat shock protein family. They were preincubated at 100°C for 15 min and then cooled on ice immediately. The chaperone-like activities of preheated proteins were measured at 37° using DTT-treated insulin B chains as substrates. Both preheated proteins exhibited greatly enhanced chaperone-like activities, accompanied with almost unchanged secondary structures and surface hydrophobicity but with a minor change in tertiary structures. The dramatically enhanced chaperone-like activities of preheated a-crystallin and Hsp16.3 may have resulted from the irreversible change in the tertiary structure as detected by near-UV CD spectra

A Nuclear-Localized Fluorescent Hydrogen Peroxide Probe for Monitoring Sirtuin-Mediated Oxidative Stress Responses In Vivo

SummaryHydrogen peroxide (H2O2) can serve as a beneficial signaling agent or toxin depending on its concentration and location within a cell or organism. Methods to measure the localized accumulation of H2O2 in living specimens remain limited. Motivated to meet this need, we have developed a nuclear-localized fluorescent probe for H2O2, Nuclear Peroxy Emerald 1 (NucPE1), to selectively interrogate ROS fluxes within this sensitive organelle. NucPE1 selectively accumulates in the nuclei of a variety of mammalian cell lines as well as in whole model organisms like Caenorhabditis elegans, where it can respond to subcellular changes in H2O2 fluxes. Moreover, in vivo NucPE1 imaging reveals a reduction in nuclear H2O2 levels in worms overexpressing sir-2.1 compared with wild-type congeners, supporting a link between this longevity-promoting sirtuin protein and enhanced regulation of nuclear ROS pools

An oxidative fluctuation hypothesis of aging generated by imaging H2O2 levels in live Caenorhabditis elegans with altered lifespans

Reactive oxygen species (ROS) are important factors mediating aging according to the free radical theory of aging. Few studies have systematically measured ROS levels in relationship to aging, partly due to the lack of tools for detection of specific ROS in live animals. By using the H₂O₂-specific fluorescence probe Peroxy Orange 1, we assayed the H₂O₂ levels of live Caenorhabditis elegans with 41 aging-related genes being individually knocked down by RNAi. Knockdown of 14 genes extends the lifespan but increases H₂O₂ level or shortens the lifespan but decreases H₂O₂ level, contradicting the free radical theory of aging. Strikingly, a significant inverse correlation between lifespan and the normalized standard deviation of H₂O₂ levels was observed (p < 0.0001). Such inverse correlation was also observed in worms cultured under heat shock conditions. An oxidative fluctuation hypothesis of aging is thus proposed and suggests that the ability of animals to homeostatically maintain the ROS levels within a narrow range is more important for lifespan extension than just minimizing the ROS levels though the latter still being crucial