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61.
Kaiser J 《Science (New York, N.Y.)》1999,284(5413):410-411
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Kaiser J 《Science (New York, N.Y.)》2008,322(5903):848-849
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A peptide 60 residues in length that corresponds to the homeo domain of Antennapedia (Antp), a protein governing development in Drosophila, was synthesized by segment condensation with protected peptide segments prepared on an oxime resin. A footprinting assay showed that the homeo domain binds specifically to a TAA repeat DNA sequence in the Antp gene. Thus the Antp homeo domain has a sequence-specific DNA binding property. The circular dichroism spectra of the homeo domain peptide showed the presence of a significant amount of alpha-helical structure in aqueous solution and in 50 percent trifluoroethanol. The alpha helicity measured in water appears to depend on the peptide concentration, which suggests that the peptide aggregates. These results support the hypothesis that the homeo domain binds to DNA through a helix-turn-helix motif. 相似文献
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Kaiser J 《Science (New York, N.Y.)》2000,289(5477):222b-223b
A volleyball-court-sized patch of bright green algae in a San Diego lagoon has set off alarm bells among ecologists and officials. Scientists strongly suspect that the algae, Caulerpa taxifolia, is the same fast-growing, non-native clone that has swept over the northwestern Mediterranean sea floor in the past decade with devastating ecological consequences. A consortium of agencies and private groups has cordoned off the lagoon and is laying plans to poison the seaweed, marking the first major U.S. attempt to stop an incipient marine species invasion. 相似文献
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Arkin IT Xu H Jensen MØ Arbely E Bennett ER Bowers KJ Chow E Dror RO Eastwood MP Flitman-Tene R Gregersen BA Klepeis JL Kolossváry I Shan Y Shaw DE 《Science (New York, N.Y.)》2007,317(5839):799-803
Na+/H+ antiporters are central to cellular salt and pH homeostasis. The structure of Escherichia coli NhaA was recently determined, but its mechanisms of transport and pH regulation remain elusive. We performed molecular dynamics simulations of NhaA that, with existing experimental data, enabled us to propose an atomically detailed model of antiporter function. Three conserved aspartates are key to our proposed mechanism: Asp164 (D164) is the Na+-binding site, D163 controls the alternating accessibility of this binding site to the cytoplasm or periplasm, and D133 is crucial for pH regulation. Consistent with experimental stoichiometry, two protons are required to transport a single Na+ ion: D163 protonates to reveal the Na+-binding site to the periplasm, and subsequent protonation of D164 releases Na+. Additional mutagenesis experiments further validated the model. 相似文献