Abstract:
:We have shown previously that hydroxyl radicals (HO*) can be produced by H2O2 and halogenated quinones, independent of transition metal ions; however, the underlying molecular mechanism is still unclear. In the present study, using the electron spin resonance secondary radical spin-trapping method, we found that tetrachloro-1,4-benzoquinone (TCBQ), but not its corresponding semiquinone anion radical, the tetrachlorosemiquinone anion radical (TCSQ*-), is essential for HO* production. The major reaction product between TCBQ and H2O2 was identified by electrospray ionization quadrupole time-of-flight mass spectrometry to be the ionic form of trichlorohydroxy-1,4-benzoquinone (TrCBQ-OH), and H2O2 was found to be the source and origin of the oxygen atom inserted into the reaction product TrCBQ-OH. On the basis of these data, we propose that HO* production by H2O2 and TCBQ is not through a semiquinone-dependent organic Fenton reaction but rather through the following mechanism: a nucleophilic attack of H2O2 to TCBQ, forming a trichlorohydroperoxyl-1,4-benzoquinone (TrCBQ-OOH) intermediate, which decomposes homolytically to produce HO*. This represents a mechanism of HO* production that does not require redox-active transition metal ions.
journal_name
Proc Natl Acad Sci U S Aauthors
Zhu BZ,Kalyanaraman B,Jiang GBdoi
10.1073/pnas.0704030104subject
Has Abstractpub_date
2007-11-06 00:00:00pages
17575-8issue
45eissn
0027-8424issn
1091-6490pii
0704030104journal_volume
104pub_type
杂志文章abstract::Protein-based hydrogels have emerged as promising alternatives to synthetic hydrogels for biomedical applications, owing to the precise control of structure and function enabled by protein engineering. Nevertheless, strategies for assembling 3D molecular networks that carry the biological information encoded in full-l...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1401291111
更新日期:2014-08-05 00:00:00
abstract::L-Gulono-gamma-lactone oxidase (L-gulono-gamma-lactone:oxygen 2-oxidoreductase, EC 1.1.3.8) is the enzyme that catalyzes the terminal step of L-ascorbic acid biosynthesis in mammalian liver. The absence of the oxidase activity in primates and guinea pigs is the reason why these animals are subject to scurvy, which mus...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.73.6.2066
更新日期:1976-06-01 00:00:00
abstract::To test for direct and indirect effects of a top predator on three lower trophic levels, we conducted two multiyear predator addition experiments in a tropical wet forest. Periodic additions of a top predator (predatory clerid beetle) to a wet forest understory shrub caused a reduction in the predatory beetle's prey (...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.96.9.5072
更新日期:1999-04-27 00:00:00
abstract::Reactive oxygen species (ROS) mediate apoptosis in many different cell types. We have previously shown that the antioxidant Mn(III) tetrakis(5,10,15,20-benzoic acid)porphyrin (MnTBAP) decreased intracellular ROS and prevented the apoptosis of activated T cells in vitro. To determine the mechanism(s) by which MnTBAP af...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1936213100
更新日期:2003-12-09 00:00:00
abstract::The structurally diverse peroxisome proliferators ciprofibrate, clofibrate, and bis(2-ethylhexyl) phthalate [(EtHx)2 greater than Pht] increase the activities of hepatic catalase and peroxisomal fatty acid beta-oxidation enzymes in conjunction with profound proliferation of peroxisomes in hepatocytes. In order to deli...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.83.6.1747
更新日期:1986-03-01 00:00:00
abstract::A continuous fluorescence-based assay is described for measuring helicase-mediated unwinding of duplex DNA. The assay utilizes an oligonucleotide substrate containing the fluorescent adenine analog, 2-aminopurine, at regular intervals. 2-Aminopurine forms a Watson-Crick-type base pair with thymine and does not distort...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.91.14.6644
更新日期:1994-07-05 00:00:00
abstract::The beta-adrenergic receptor kinase (beta ARK) phosphorylates its membrane-associated receptor substrates, such as the beta-adrenergic receptor, triggering events leading to receptor desensitization. beta ARK activity is markedly stimulated by the isoprenylated beta gamma subunit complex of heterotrimeric guanine nucl...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.91.9.3637
更新日期:1994-04-26 00:00:00
abstract::The hepatic pigment accumulated in 3,5-diethoxycarbonyl-1,4-dihydrocollidine-treated rats, which has been reported to inhibit ferrochelatase, has been isolated and purified. The pigment has been resolved into one major, one minor, and two trace components, all of which appear to be isomeric porphyrins. The major fract...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.78.3.1490
更新日期:1981-03-01 00:00:00
abstract::This article reports the development of an optical imaging technique, confocal light absorption and scattering spectroscopic (CLASS) microscopy, capable of noninvasively determining the dimensions and other physical properties of single subcellular organelles. CLASS microscopy combines the principles of light-scatteri...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0708669104
更新日期:2007-10-30 00:00:00
abstract::The transcription factor cAMP response element (CRE)-binding protein (CREB) has been shown to regulate neural plasticity. Drugs of abuse activate CREB in the nucleus accumbens, an important part of the brain's reward pathways, and local manipulations of CREB activity have been shown to affect cocaine reward, suggestin...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.172091899
更新日期:2002-08-20 00:00:00
abstract::Multiple sclerosis (MS) is an autoimmune inflammatory demyelinating disease of the CNS that causes disability in young adults as a result of the irreversible accumulation of neurological deficits. Although there are potent disease-modifying agents for its initial relapsing-remitting phase, these therapies show limited...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1615413114
更新日期:2017-02-21 00:00:00
abstract::The two large cytoplasmic domains (C1 and C2) of adenylyl cyclases (AC), when expressed separately and mixed together, reconstitute enzyme activity that can be regulated by various modulators. Therefore, we have used the C1 or its C1a subdomain and C2 regions from type I AC (ACI) and type V AC (ACV) to identify the re...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.96.17.9551
更新日期:1999-08-17 00:00:00
abstract::We investigated the influence of interareal distance on connectivity patterns in a database obtained from the injection of retrograde tracers in 29 areas distributed over six regions (occipital, temporal, parietal, frontal, prefrontal, and limbic). One-third of the 1,615 pathways projecting to the 29 target areas were...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1218972110
更新日期:2013-03-26 00:00:00
abstract::Linkage disequilibrium between polymorphisms in a natural population may result from various evolutionary forces, including random genetic drift due to sampling of gametes during reproduction, restricted migration between subpopulations in a subdivided population, or epistatic selection. In this report, we present evi...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.92.20.9047
更新日期:1995-09-26 00:00:00
abstract::In virtually every real-life situation humans are confronted with complex and cluttered visual environments that contain a multitude of objects. Because of the limited capacity of the visual system, objects compete for neural representation and cognitive processing resources. Previous work has shown that such attentio...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章,随机对照试验
doi:10.1073/pnas.1400559111
更新日期:2014-07-29 00:00:00
abstract::In the goldfish, the optic nerve decussation occurs without intermingling of fibers from the two eyes. In two-thirds of juvenile and adult specimens, the left optic nerve is dorsal at the midline. In about 60% of the specimens, the decussation of Mauthner's neuron also has a left-dorsal-to-right (L/R) configuration. C...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.76.8.4131
更新日期:1979-08-01 00:00:00
abstract::In vitro translation of cellular poly(A)+ RNA coupled with immunoprecipitation was developed as a technique for characterizing 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] receptors and assessing receptor mRNA activity. Cell-free translation of poly(A)+ RNA isolated from chicken intestine revealed two immunoprecipitable fo...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.84.2.354
更新日期:1987-01-01 00:00:00
abstract::Although tumor necrosis factor (TNF) and interleukin 1 (IL-1) affect many cell functions, the molecular mechanisms of TNF and IL-1 action are not understood. Our present study shows that exposure of human FS-4 fibroblasts to TNF or IL-1 caused a rapid accumulation of intracellular cAMP and an increase in protein kinas...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.85.18.6802
更新日期:1988-09-01 00:00:00
abstract::Ultrastructural immunocytochemical studies of the expression of major histocompatibility complex class I antigens in the placentas of inbred rats were performed using placentas derived from natural matings and from embryo transfers into females made pseudopregnant by mechanical stimulation. The studies utilized the WF...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.87.1.444
更新日期:1990-01-01 00:00:00
abstract::A fundamental mystery of plant cell biology is the occurrence of "stromules," stroma-filled tubular extensions from plastids (such as chloroplasts) that are universally observed in plants but whose functions are, in effect, completely unknown. One prevalent hypothesis is that stromules exchange signals or metabolites ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1511570112
更新日期:2015-08-11 00:00:00
abstract::In some countries across the globe, tropical forest cover is increasing. The national-scale reforestation of Vietnam since 1992 is assumed to contribute to this recovery. It is achieved, however, by the displacement of forest extraction to other countries on the order of 49 (34-70) M m(3), or approximately 39% of the ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0904942106
更新日期:2009-09-22 00:00:00
abstract::The Xlim-1 gene is activated in the late blastula stage of Xenopus embryogenesis in the mesoderm, and its RNA product becomes concentrated in the Spemann organizer at early gastrula stage. A major regulator of early expression of Xlim-1 is activin or an activin-like signal. We report experiments aiming to identify the...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.94.18.9717
更新日期:1997-09-02 00:00:00
abstract::We perform a generalized-ensemble simulation of a small peptide taking the interactions among all atoms into account. From this simulation we obtain thermodynamic quantities over a wide range of temperatures. In particular, we show that the folding of a small peptide is a multistage process associated with two charact...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.94.20.10652
更新日期:1997-09-30 00:00:00
abstract::The regulation of protein function through ligand-induced conformational changes is crucial for many signal transduction processes. The binding of a ligand alters the delicate energy balance within the protein structure, eventually leading to such conformational changes. In this study, we elucidate the energetic and m...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1504625112
更新日期:2015-08-18 00:00:00
abstract::Several Bradyrhizobium species nodulate the leguminous plant Aeschynomene indica in a type III secretion system-dependent manner, independently of Nod factors. To date, the underlying molecular determinants involved in this symbiotic process remain unknown. To identify the rhizobial effectors involved in nodulation, w...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1904456116
更新日期:2019-10-22 00:00:00
abstract::Human interleukin 12 and interleukin 23 (IL12/23) influence susceptibility or resistance to multiple diseases. However, the reasons underlying individual differences in IL12/23 sensitivity remain poorly understood. Here we report that in human peripheral blood mononuclear cells (PBMCs) and inflamed lungs, the majority...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1515978112
更新日期:2015-12-15 00:00:00
abstract::The substrate specificity of the catalytic subunit of rabbit skeletal muscle 3': 5'-cyclic AMP-dependent protein kinase (EC 2.7.1.37; ATP: protein phosphotransferase) has been studied using the synthetic peptide Arg-Gly-Tyr-Ser-Leu-Gly corresponding to the sequence around serine 24, a phosphorylation site in reduced, ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.73.4.1038
更新日期:1976-04-01 00:00:00
abstract::The mathematical theory of compressed sensing (CS) asserts that one can acquire signals from measurements whose rate is much lower than the total bandwidth. Whereas the CS theory is now well developed, challenges concerning hardware implementations of CS-based acquisition devices--especially in optics--have only start...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1119511109
更新日期:2012-06-26 00:00:00
abstract::A cloned Bacillus subtilis gene (sprE) expressed only during the stationary growth phase is shown to encode the subtilisin E protease, an enzyme associated with sporulation. We have determined the DNA sequence of the sprE promoter region and the promoter-proximal half of the structural gene. The sprE gene codes for a ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.81.4.1184
更新日期:1984-02-01 00:00:00
abstract::The lentiviruses are associated with a wide range of chronic diseases in mammals. These include immunodeficiencies (such as HIV/AIDS in humans), malignancies, and lymphatic and neurological disorders in primates, felids, and a variety of wild and domesticated ungulates. Evolutionary analyses of the genomic sequences o...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0700471104
更新日期:2007-04-10 00:00:00