Abstract:
:The self-assembled heterocapsule 1.2, which is formed by the hydrogen bonds of tetra(4-pyridyl)-cavitand 1 and tetrakis(4-hydroxyphenyl)-cavitand 2, encapsulates 1 molecule of guests such as 1,4-diacetoxybenzene 3a, 1,4-diacetoxy-2,5-dimethylbenzene 3b, 1,4-diacetoxy-2,5-dialkoxybenzenes (3c, OCH(3); 3d, OC(2)H(5); 3e, OC(3)H(7); 3f, OC(4)H(9); 3g, OC(5)H(11); 3h, OC(6)H(13); 3i, OC(8)H(17)), 1,4-diacetoxy-2,5-difluorobenzene 4a, and 1,4-diacetoxy-2,3-difluorobenzene 4b. The X-ray crystallographic analysis of 3c@(1.2) showed that the acetoxy groups at the 1,4-positions of 3c are oriented toward the 2 aromatic cavity ends of 1.2 and that 3c can rotate along the long axis of 1.2. Thus, the 1.2 (stator) with the encapsulation guest (rotator) behaves as a supramolecular gyroscope. A variable temperature (VT) (1)H NMR study in CDCl(3) showed that 3a, 3b, 4a, and 4b within 1.2 rotate rapidly even at 218 K, whereas guest rotation is almost inhibited for 3h and 3i even at 323 K. In this respect, 4b with a large dipole moment is a good candidate for the rotator of 1.2. For 3c-3g, the enthalpic (DeltaH(double dagger)) and entropic (DeltaS(double dagger)) contributions to the free energy of activation (DeltaG(double dagger)) for the guest-rotational steric barriers within 1.2 were obtained from Eyring plots based on line-shape analysis of the VT (1)H NMR spectra. The value of DeltaG(double dagger) increased in the order 3c < 3d < 3e < 3f < 3g. Thus, the elongation of the alkoxy chains at the 2,5-positions of 3 puts the brakes on guest rotation within 1.2.
journal_name
Proc Natl Acad Sci U S Aauthors
Kitagawa H,Kobori Y,Yamanaka M,Yoza K,Kobayashi Kdoi
10.1073/pnas.0812660106subject
Has Abstractpub_date
2009-06-30 00:00:00pages
10444-8issue
26eissn
0027-8424issn
1091-6490pii
0812660106journal_volume
106pub_type
杂志文章abstract::Phytosulfokine-alpha [PSK-alpha, Tyr(SO(3)H)-Ile-Tyr(SO(3)H)-Thr-Gln], a sulfated mitogenic peptide found in plants, strongly promotes proliferation of plant cells in culture at very low concentrations. Oryza sativa PSK (OsPSK) cDNA encoding a PSK-alpha precursor has been isolated. The cDNA is 725 base pairs long, and...
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.96.23.13560
更新日期:1999-11-09 00:00:00
abstract::Insects, as a group, have been remarkably successful in adapting to a great range of physical and biological environments, in large part because of their ability to fly. The evolution of flight in small insects was accompanied by striking adaptations of the thoracic musculature that enabled very high wing beat frequen...
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.0604972103
更新日期:2006-11-14 00:00:00
abstract::Chronic myeloid leukemia (CML) is associated with the Philadelphia chromosome, which arises by a reciprocal translocation between chromosomes 9 and 22 and harbors the BCR-ABL fusion oncogene. It is unknown whether any other mutations are needed for the chronic phase of the disease. The CML incidence increases as a fun...
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.0607006103
更新日期:2006-10-03 00:00:00
abstract::The internal promoter of the Xenopus laevis oocyte-type 5S RNA gene is preferentially cleaved by S1 and Bal-31 nucleases in plasmid DNA. S1 nuclease sensitivity is largely dependent on supercoiling; however, Bal-31 cleaves within the 5S RNA gene in linear as well as in supercoiled DNA. The S1 nuclease-hypersensitive s...
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.82.12.4018
更新日期:1985-06-01 00:00:00
abstract::Because previous studies showed that polyunsaturated fatty acids can reduce the contraction rate of spontaneously beating heart cells and have antiarrhythmic effects, we examined the effects of the fatty acids on the electrophysiology of the cardiac cycle in isolated neonatal rat cardiac myocytes. Exposure of cardiomy...
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.92.9.3997
更新日期:1995-04-25 00:00:00
abstract::Members of the tumor necrosis factor receptor (TNFR) superfamily are important for cell growth and survival. In addition to providing costimulatory signals for cell proliferation, ligation of both TNFR1 and Fas can result in programmed cell death or apoptosis. The underlying mechanism requires an intact 80-aa stretch ...
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.94.12.6346
更新日期:1997-06-10 00:00:00
abstract::Multiple studies have established that microRNAs (miRNAs) are involved in the initiation and progression of cancer. Notably, miR-155 is one of the most overexpressed miRNAs in several solid and hematological malignancies. Ectopic miR-155 expression in mice B cells (Eμ-miR-155 transgenic mice) has been shown to induce ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章,meta分析
doi:10.1073/pnas.1213764109
更新日期:2012-12-04 00:00:00
abstract::The mammalian intestinal epithelium undergoes continuous and rapid renewal of its four principal terminally differentiated cell types. These cells arise from multipotent stem cells located at or near the base of the crypts of Lieberkühn. The differentiation process is precisely organized along two spatial dimensions (...
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.87.16.6408
更新日期:1990-08-01 00:00:00
abstract::Biotin plays an essential role in growth of mycobacteria. Synthesis of the cofactor is essential for Mycobacterium tuberculosis to establish and maintain chronic infections in a murine model of tuberculosis. Although the late steps of mycobacterial biotin synthesis, assembly of the heterocyclic rings, are thought to f...
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.2010189117
更新日期:2020-09-22 00:00:00
abstract::A 1,942-base-pair DNA segment encoding the structural gene for diphtheria toxin was sequenced, and the primary structure of the toxin was deduced. Restriction enzyme fragments corresponding to nontoxic or hypotoxic peptides of the toxin were isolated from corynebacteriophage beta and cloned into Escherichia coli on pl...
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.80.22.6853
更新日期:1983-11-01 00:00:00
abstract::Deletion of 13 amino acids from the carboxyl terminus of the 149-amino acid staphylococcal nuclease molecule results in a denatured, partly unfolded molecule that lacks persistent secondary structure but is compact under physiological conditions. Since the modification is a carboxyl-terminal deletion, it is argued tha...
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.89.2.748
更新日期:1992-01-15 00:00:00
abstract::A molecular dynamics study was performed to compare the differences in the active-site dynamics of the wild-type and W137F mutant enzymes of 4-chlorobenzoyl-CoA dehalogenase. Only in the wild-type simulation are conformations formed between the catalytic Asp-145 and 4-chlorobenzoyl-CoA, which resemble the ab initio ca...
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.161282698
更新日期:2001-08-14 00:00:00
abstract::The transformation of human cells was examined by transfection of cloned oncogenic DNAs derived from the tumor virus simian virus 40 and from the human bladder carcinoma cell line EJ into diploid fibroblasts derived from foreskin (FS-2 cells). The simian virus 40 DNA was found to induce a morphologically transformed 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.80.24.7601
更新日期:1983-12-01 00:00:00
abstract::Measures of complexity derived from ergodic theory of dynamical systems were developed and applied to an exemplary data set describing locomotor movements of rats in a bounded space. A symbolic dynamical system was obtained by partitioning the event space into equally probable partition elements, using a k-dimensional...
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.87.2.723
更新日期:1990-01-01 00:00:00
abstract::Appropriate expression of IL-2 plays a central role during the priming and differentiation of T cells. A tight balance between IL-2 and the effector cytokine IL-17A is essential for immune homeostasis. Epigenetic mechanisms have been documented as a key component of cytokine regulation during lineage commitment. The 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.1210129109
更新日期:2012-10-09 00:00:00
abstract::Global biological datasets generated by genomics, transcriptomics, and proteomics provide new approaches to understanding the relationship between the genome and the synapse. Combined transcriptome analysis and multielectrode recordings of neuronal network activity were used in mouse embryonic primary neuronal culture...
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.0609071104
更新日期:2007-03-13 00:00:00
abstract::Here we describe a strategy designed to identify RNAs that are actively transported to synapses during learning. Our approach is based on the characterization of RNA transport complexes carried by molecular motor kinesin. Using this strategy in Aplysia, we have identified 5,657 unique sequences consisting of both codi...
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.1304422110
更新日期:2013-04-30 00:00:00
abstract::Photosynthetic water splitting, coupled to hydrogenase-catalyzed hydrogen production, is considered a promising clean, renewable source of energy. It is widely accepted that the oxygen sensitivity of hydrogen production, combined with competition between hydrogenases and NADPH-dependent carbon dioxide fixation are 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.1103659108
更新日期:2011-06-07 00:00:00
abstract::Misfolded proteins are eliminated from the endoplasmic reticulum (ER) by retrotranslocation into the cytosol, a pathway hijacked by certain viruses to destroy MHC class I heavy chains. The translocation of polypeptides across the ER membrane requires their polyubiquitination and subsequent extraction from the membrane...
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.0505006102
更新日期:2005-10-04 00:00:00
abstract::Bones from a stratified sedimentary deposit in the Puu Naio Cave site on Maui, Hawaiian Islands, reveal the late Holocene extinction of 19 species of birds. The age of the sediment and associated fauna was determined by direct radiocarbon dating (tandem particle accelerator-mass spectrometer; TAMS) of amino acids extr...
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.84.8.2350
更新日期:1987-04-01 00:00:00
abstract::The marine nitrogen fixing microorganisms (diazotrophs) are a major source of nitrogen to open ocean ecosystems and are predicted to be limited by iron in most marine environments. Here we use global and targeted proteomic analyses on a key unicellular marine diazotroph Crocosphaera watsonii to reveal large scale diel...
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.1006943108
更新日期:2011-02-08 00:00:00
abstract::Papain solubilized H-2a histocompatibility antigens (H-2Kk plus H-2Dd) have been purified by a large-scale procedure that can routinely provide 2-3 mg of heavy chain from 1 kg of mouse liver. The heavy chains were homogeneous by sodium dodecyl sulfate electrophoresis. Disc gel electrophoresis resolved two protein band...
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.75.7.3322
更新日期:1978-07-01 00:00:00
abstract::Lignocellulosic plant biomass is an attractive feedstock for the production of sustainable biofuels, but the commercialization of such products is hampered by the high costs of processing this material into fermentable sugars (saccharification). One approach to lowering these costs is to produce crops with cell walls ...
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.1414020111
更新日期:2014-10-07 00:00:00
abstract::Migration of the cells in osteoblastic lineage, including preosteoblasts and osteoblasts, has been postulated to influence bone formation. However, the molecular bases that link preosteoblastic/osteoblastic cell migration and bone formation are incompletely understood. Nck (noncatalytic region of tyrosine kinase; coll...
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.1518253112
更新日期:2015-12-15 00:00:00
abstract::Infection with avian influenza A virus of the H5N1 subtype (isolates A/HK/212/03 and A/HK/213/03) was fatal to one of two members of a family in southern China in 2003. This incident was preceded by lethal outbreaks of H5N1 influenza in waterfowl, which are the natural hosts of these viruses and, therefore, normally h...
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.0402443101
更新日期:2004-05-25 00:00:00
abstract::The first step in the formation of the protease resistant form (PrPSc) of prion proteins involves a conformational transition of the monomeric cellular form of PrPC to a more stable aggregation prone state PrPC*. A search of PDBselect and Escherichia coli and yeast genomes shows that the exact pattern of charges in he...
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.0404235101
更新日期:2004-10-26 00:00:00
abstract::The plant photoreceptor phytochrome plays an important role in the nucleus as a regulator of transcription. Numerous studies imply, however, that phytochromes in both higher and lower plants mediate physiological reactions within the cytoplasm. In particular, the tip cells of moss protonemal filaments use phytochrome ...
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.0403140101
更新日期:2004-09-21 00:00:00
abstract::To study the role of low-abundance, embryonic muscle-specific gene transcripts, we have developed a method to screen cDNA clones from embryonic muscle for such sequences. The protocol involves two stages: first, partial enrichment for cDNA clones carrying possible embryo-specific sequences by selecting clones of low-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.77.8.4519
更新日期:1980-08-01 00:00:00
abstract::The origin of plant chemical ecology generally dates to the late 1950s, when evolutionary entomologists recognized the essential role of plant secondary metabolites in plant-insect interactions and suggested that plant chemical diversity evolved under the selection pressure of herbivory. However, similar ideas had alr...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 传,历史文章,杂志文章
doi:10.1073/pnas.0709231105
更新日期:2008-03-25 00:00:00
abstract::To study the permanency of response to selection for a quantitative character in finite populations and the nature of the genetic effects that contribute to this response, we have used the covariance between ancestors and descendents within populations. Effects and variances are defined for an initial equilibrium rand...
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.85.5.1563
更新日期:1988-03-01 00:00:00