Abstract:
:Asymmetric epoxidation of various styrenes using carbocyclic oxazolidinone-containing ketone 3 has been investigated. High enantioselectivity (89-93% enantiomeric excess) has been attained for this challenging class of alkenes. Mechanistic studies show that substituents on the ketone catalyst can have electronic influences on secondary orbital interactions, which affects the competition between spiro and planar transition states and, ultimately, enantioselectivity. The results described herein not only reveal the potential of chiral dioxirane catalyzed asymmetric epoxidation as a viable entry into this important class of olefins but also further enhance the understanding of the mechanistic aspects of chiral ketone-catalyzed asymmetric epoxidation.
journal_name
Proc Natl Acad Sci U S Aauthors
Hickey M,Goeddel D,Crane Z,Shi Ydoi
10.1073/pnas.0307548101keywords:
subject
Has Abstractpub_date
2004-04-20 00:00:00pages
5794-8issue
16eissn
0027-8424issn
1091-6490pii
0307548101journal_volume
101pub_type
杂志文章abstract::Glucocorticoids rapidly and completely inhibit intracellular plasminogen activator activity in rat hepatoma cells, as assayed by the solubilization of 125I-labeled fibrin. Experiments in which extracts of dexamethasone-treated cells are mixed with extracts of control cells demonstrate an inhibitor of protease activity...
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.75.12.6130
更新日期:1978-12-01 00:00:00
abstract::The Per-Arnt-Sim (PAS) domain is a ubiquitous protein module with a common three-dimensional fold involved in a wide range of regulatory and sensory functions in all domains of life. The activation of these functions is thought to involve partial unfolding of N- or C-terminal helices attached to the PAS domain. Here 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.0601567103
更新日期:2006-08-01 00:00:00
abstract::A nongenetic, transgenerational effect of parental age on offspring fitness has been described in many taxa in the laboratory. Such a transgenerational fitness effect will have important influences on population dynamics, population age structure, and the evolution of aging and lifespan. However, effects of parental 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.1422715112
更新日期:2015-03-31 00:00:00
abstract::An open question remains as to what coordinates cell behavior during organogenesis, permitting organs to reach their appropriate size and shape. The Arabidopsis gene STRUBBELIG (SUB) defines a receptor-mediated signaling pathway in plants. SUB encodes a putative leucine-rich repeat transmembrane receptor-like kinase. ...
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.0503526102
更新日期:2005-06-21 00:00:00
abstract::Saccharomyces cerevisiae strains harboring a nonreciprocal, bridge-induced translocation (BIT) between chromosomes VIII and XV exhibited an abnormal phenotype comprising elongated buds and multibudded, unevenly nucleated pseudohyphae. In these cells, we found evidence of molecular effects elicited by the translocation...
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.0800464105
更新日期:2008-07-15 00:00:00
abstract::Chemical coding in the sympathetic nervous system involves both noradrenergic and, for a minority of neurons, cholinergic neurotransmission. The expression of the cholinergic phenotype in the developing sympathetic nervous system was examined to determine if coding for cholinergic transmission occurs before or after i...
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.94.8.4149
更新日期:1997-04-15 00:00:00
abstract::In recent years, advertisers and magazine editors have been widely criticized for taking digital photo retouching to an extreme. Impossibly thin, tall, and wrinkle- and blemish-free models are routinely splashed onto billboards, advertisements, and magazine covers. The ubiquity of these unrealistic and highly idealize...
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.1110747108
更新日期:2011-12-13 00:00:00
abstract::Two-dimensional molecular aggregate (2DMA), a thin sheet of strongly interacting dipole molecules self-assembled at close distance on an ordered lattice, is a fascinating fluorescent material. It is distinctively different from the conventional (single or colloidal) dye molecules and quantum dots. In this paper, we ve...
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.1703000114
更新日期:2017-09-19 00:00:00
abstract::The Lyz endolysin of bacteriophage P1 was found to cause lysis of the host without a holin. Induction of a plasmid-cloned lyz resulted in lysis, and the lytic event could be triggered prematurely by treatments that dissipate the proton-motive force. Instead of requiring a holin, export was mediated by an N-terminal tr...
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.0400957101
更新日期:2004-04-27 00:00:00
abstract::The RuvB protein is induced in Escherichia coli as part of the SOS response to DNA damage. It is required for genetic recombination and the postreplication repair of DNA. In vitro, the RuvB protein promotes the branch migration of Holliday junctions and has a DNA helicase activity in reactions that require ATP hydroly...
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.91.16.7618
更新日期:1994-08-02 00:00:00
abstract::Alzheimer's disease (AD) is the most prevalent of a large group of related proteinopathies for which there is currently no cure. Here, we used Drosophila to explore a strategy to block Aβ42 neurotoxicity through engineering of the Heat shock protein 70 (Hsp70), a chaperone that has demonstrated neuroprotective activit...
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.1608045113
更新日期:2016-08-30 00:00:00
abstract::Pulmonary surfactant contains two hydrophobic polypeptides, SP-B and SP-C, with known amino acid sequences and with truncated subforms lacking the N-terminal residues. Treatment of SP-C with KOH releases fatty acids (palmitic acid to more than 85%) in molar ratios of 1.8-2.0 relative to the polypeptide. Furthermore, p...
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.87.8.2985
更新日期:1990-04-01 00:00:00
abstract::Several natural isolate E. coli strains highly resistant to sulfonamides and antibiotics are shown to contain a sulfonamide-resistant dihydropteroate synthase (2-amino-4-hydroxy-6-hydroxymethyl-7,8-dihydropteridine-diphosphate:4-aminobenzoate 2-amino-4-hydroxydihydropteridine-6-methenyltransferase, EC 2.5.1.15) in add...
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.72.7.2621
更新日期:1975-07-01 00:00:00
abstract::The Pyrococcus furiosus (PF) ornithine carbamoyltransferase (OTCase; EC 2.1.3.3) is an extremely heat-stable enzyme that maintains about 50% of its activity after heat treatment for 60 min at 100 degrees C. To understand the molecular basis of thermostability of this enzyme, we have determined its three-dimensional st...
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.95.6.2801
更新日期:1998-03-17 00:00:00
abstract::An emergent viral pathogen termed severe fever with thrombocytopenia syndrome virus (SFTSV) is responsible for thousands of clinical cases and associated fatalities in China, Japan, and South Korea. Akin to other phleboviruses, SFTSV relies on a viral glycoprotein, Gc, to catalyze the merger of endosomal host and vira...
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.1603827113
更新日期:2016-06-28 00:00:00
abstract::Regulation of hexose transport in NIL hamster fibroblasts has been studied in confluent cultures preconditioned for 24 hr in media deprived of glutamine or of serum or of both. Cultures maintained in media containing dialyzed fetal calf serum and 4 mM glutamine accumulated up to 72 nmol of glutamine per mg of cell pro...
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.77.10.5958
更新日期:1980-10-01 00:00:00
abstract::Wnt/beta-catenin signaling controls various cell fates in metazoan development and is misregulated in several cancers and developmental disorders. Binding of a Wnt ligand to its transmembrane coreceptors inhibits phosphorylation and degradation of the transcriptional coactivator beta-catenin, which then translocates t...
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.0803025105
更新日期:2008-06-10 00:00:00
abstract::Arachidonic acid (AA) has recently been shown to influence various cellular functions in the central nervous system. Here we report that AA increases, in a time- and concentration-dependent manner, 2-deoxy-D-[1-3H]glucose ([3H]2DG) uptake in primary cultures of astrocytes prepared from the cerebral cortex of neonatal ...
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.90.9.4042
更新日期:1993-05-01 00:00:00
abstract::Regional differences in neurons, astrocytes, oligodendrocytes, and microglia exist in the brain during health, and regional differences in the transcriptome may occur for each cell type during neurodegeneration. Multiple sclerosis (MS) is multifocal, and regional differences in the astrocyte transcriptome occur in exp...
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.1821306116
更新日期:2019-05-14 00:00:00
abstract::The cellular basis of the magnetic sense remains an unsolved scientific mystery. One theory that aims to explain how animals detect the magnetic field is the magnetite hypothesis. It argues that intracellular crystals of the iron oxide magnetite (Fe3O4) are coupled to mechanosensitive channels that elicit neuronal act...
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.1407915112
更新日期:2015-01-06 00:00:00
abstract::Although pain is a prevalent nonmotor symptom in Parkinson's disease (PD), it is undertreated, in part because of our limited understanding of the underlying mechanisms. Considering that the basal ganglia are implicated in pain sensation, and that their synaptic outputs are controlled by the subthalamic nucleus (STN),...
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.1916263117
更新日期:2020-05-05 00:00:00
abstract::Infectious RNA transcripts were generated from full-length cDNA clones of the tobacco etch potyvirus genome containing an insertion of the bacterial beta-glucuronidase (GUS) gene between the polyprotein-coding sequences for the N-terminal 35-kDa proteinase and the helper component-proteinase. The recombinant virus was...
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.89.21.10208
更新日期:1992-11-01 00:00:00
abstract::We examined the origins and functional evolution of the Shaker and KCNQ families of voltage-gated K(+) channels to better understand how neuronal excitability evolved. In bilaterians, the Shaker family consists of four functionally distinct gene families (Shaker, Shab, Shal, and Shaw) that share a subunit structure co...
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.1422941112
更新日期:2015-03-03 00:00:00
abstract::The ecological niche is a key concept for elucidating patterns of species distributions and developing strategies for conserving biodiversity. However, recent times are seeing a widespread debate whether species niches are conserved across space and time (niche conservatism hypothesis). Biological invasions represent ...
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.2004289117
更新日期:2020-09-22 00:00:00
abstract::Life history events, such as traumatic stress, illness, or starvation, can influence us through molecular changes that are recorded in a pattern of characteristic chromatin modifications. These modifications are often associated with adaptive adjustments in gene expression that can persist throughout the lifetime of t...
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.1616171114
更新日期:2017-03-28 00:00:00
abstract::Understanding the detailed mechanism of the activation of voltage-gated ion channels has been a problem of great current interest. Reliable molecular simulations of voltage effects present a major challenge because meaningful converging microscopic simulations are not yet available and macroscopic treatments involve 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.1121094109
更新日期:2012-02-28 00:00:00
abstract::Chondrules may have played a critical role in the earliest stages of planet formation by mediating the accumulation of dust into planetesimals. However, the origin of chondrules and their significance for planetesimal accretion remain enigmatic. Here, we show that chondrules and matrix in the carbonaceous chondrite Al...
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.1524980113
更新日期:2016-03-15 00:00:00
abstract::We have isolated CaKRE9, a gene from Candida albicans, that is a functional homologue of the Saccharomyces cerevisiae KRE9 gene involved in beta-1,6-glucan synthesis. Disruption of the CaKRE9 gene in C. albicans shows that CaKre9p is required for the synthesis or assembly of this fungal polymer. Homozygous null disrup...
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.95.17.9825
更新日期:1998-08-18 00:00:00
abstract::Caenorhabditis elegans sqv mutants are defective in vulval epithelial invagination and have a severe reduction in hermaphrodite fertility. The gene sqv-7 encodes a multitransmembrane hydrophobic protein resembling nucleotide sugar transporters of the Golgi membrane. A Golgi vesicle enriched fraction of Saccharomyces 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.061593098
更新日期:2001-03-27 00:00:00
abstract::Agricultural landscape homogenization has detrimental effects on biodiversity and key ecosystem services. Increasing agricultural landscape heterogeneity by increasing seminatural cover can help to mitigate biodiversity loss. However, the amount of seminatural cover is generally low and difficult to increase in many i...
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.1906419116
更新日期:2019-08-13 00:00:00