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Paradoxical hot spots for guanine oxidation by a chemical mediator of inflammation. Margolin et al. (p 365) describe the unusual sequence selectivity for DNA oxidation by an important chemical mediator of inflammation, nitrosoperoxycarbonate. Contrary to classical one-electron oxidants, which selectively produce damage at guanine bases having the lowest sequence-dependent ionization potential, this macrophage-derived oxidant produces the most damage at guanines in sequence contexts that confer the highest ionization potentials (see also News & Views by Cadet, Douki & Ravant, p 348). This observation complicates models that attempt to predict the location of oxidative DNA damage in cells. Cover art by Jeff Dixon (http://www.jeffdixon.ca) depicts an activated macrophage generating nitric oxide and superoxide that, along with carbon dioxide, react to form nitrosoperoxycarbonate. Homolytic bond cleavage produces nitrogen dioxide and carbonate radical anion, and the latter oxidizes a solvent-accessible guanine in DNA.
Nitrosoperoxycarbonate anion, a reactive species generated in inflammation processes, is able to specifically oxidize guanine bases with a sequence selectivity that is almost opposite from that usually observed for one-electron oxidants.
Nitric oxide (NO) regulates a broad range of biological processes, yet many intracellular details of NO-mediated processes remain hidden. A new fluorescein derivative capable of direct detection provides a key advance in determining NO function in vivo.
One-bead-one-compound combinatorial peptidomimetic libraries, in conjunction with a high-stringency screening method, are a powerful tool for screening peptide and peptidomimetic ligands for target proteins. Picomolar-affinity peptidomimetics for the integrin α4β1 have now been developed and have been successfully used to image α4β1-expressing tumors in living mice.
Copper is a requisite cofactor in myriad cellular enzymes and is shuttled to different cellular sites for the assembly of copper-containing enzymes by Cu(I)-binding metallochaperones. NMR structural studies now reveal a key step in copper ion trafficking to sites of use.
DNA-binding proteins accomplish the remarkable feat of finding their correct target sequences within a sea of genomic DNA. A new study uses NMR spectroscopy to show the mechanism by which proteins may hop between and slide along DNA as they search for their target binding sites.
Dynamin is a large GTPase that participates in the severing of membrane-bound vesicles. A small-molecule inhibitor specific for the dynamin family of GTPases has been identified and reveals new aspects of membrane dynamics.