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1.
The neutral mononuclear vanadyl complex with the quinolone antibacterial drug enrofloxacin has been prepared and characterized with physicochemical and spectroscopic techniques and molecular mechanics calculations. The interaction of the complex with calf-thymus DNA has also been investigated and the antimicrobial activity has been evaluated against three different microorganisms.  相似文献   

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The data reported in the literature concerning the uses and composition of yarrow,Achillea millefolium aggr., Compositae, are compiled and discussed. Historically, this plant has been extensively used as a herbal remedy for numerous afflictions by many cultures on several continents. It has also been the subject of a considerable number of scientific investigations. It has, however, not been previously reviewed. Analysis of available information demonstrates the value of continued phytochemical investigations of folklore remedies.  相似文献   

4.
Mycopathologia - Recently, Trichosporon taxonomy has been reevaluated and new genera of the Trichosporonaceae family have been described. Here, 26 clinical isolates were submitted for...  相似文献   

5.
The stability between helical conformations of homopeptides of alanine, glycine, and aminoisobutyric acid has been studied by means of quantum-mechanical methods. The influence of peptide length on the relative stability between helical conformations has also been analyzed by means of systematic studies for peptides of size up to 11 residues. Finally, the influence of the solvent has been examined by using self-consistent reaction field methods. The results provide a detailed picture of the modulation exerted by these factors on the helical preferences of these peptides. © 1997 Wiley-Liss Inc.  相似文献   

6.
Purification, cloning, and expression of the prolactin receptor   总被引:1,自引:0,他引:1  
The rat liver prolactin receptor has been purified to homogeneity, and partial amino acid sequences have been obtained. The structure of the receptor has been deduced from a single complementary DNA clone. The mature protein of 291 amino acids has a relatively long extracellular region, a single transmembrane segment, and a short (57 amino acids) cytoplasmic domain. With the rat cDNA used as a probe, the prolactin receptor in rabbit mammary gland and human hepatoma cells has also been isolated. These tissues contain a second, longer form of the receptor (592 and 598 amino acids, respectively). Both the short and long forms of the prolactin receptor show regions of strong sequence identity with the human and rabbit growth hormone receptors, suggesting that the prolactin and growth hormone receptors originate from a common ancestor.  相似文献   

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Fossil brachiopods from the Ordovician, Silurian, Devonian, Carboniferous, and Permian deposits of Mongolia have been studied for the last forty-five years by the Joint Soviet-Mongolian (later RussianMongolian) Paleontological and Geological Expeditions. New data on the taxonomic composition, stratigraphic and geographic distribution of the brachiopod assemblages have been obtained. The brachiopod systematics has been further refined and detailed, and the stratigraphic and correlation scales and biogeographic reconstructions have been elaborated for the Paleozoic of Mongolia.  相似文献   

9.
Profiles of endogenous peptides of the brain, heart, lungs, and spleen of a rat have been obtained by chromatographic and mass spectrometric analysis of low-molecular-mass fractions of tissues extracts. The concentrations of the corresponding components have been estimated from the intensities of 119 major chromatographic peaks. The total content of peptides in tissues, nmol/g (mg/g), was 3–13 (0.005–0.05) for the brain, 7–27 (0.01–0.10) for the heart, 17–68 (0.02–0.25) for the lungs, and 80–300 (0.08–1.30) for the spleen. A comparative analysis of the data obtained for the organs has been performed. The primary structures for 68 peptides have been determined; most substances (>70%) have been identified as hemoglobin fragments. It has been shown that many of the peptide components identified (>75%) are common for several organs. The relationship between the composition, the mechanism of formation, and the functional role of peptidomes of the organs, tissues, and cells of higher organisms has been discussed.  相似文献   

10.
The protease which initiates the massive protein degradation early in bacterial spore germination has been purified from Bacillus megaterium spores. The enzyme has a molecular weight of 160,000 and contains four apparently identical subunits, but only the tetramer is enzymatically active. A radioimmunoassay has been developed for this enzyme and has been used to show that the protease is absent from growing cells, but appears early in sporulation within the developing forespore. In contrast, the protease antigen disappears rapidly during spore germination, in parallel with the loss in enzyme activity.  相似文献   

11.
Leishmania major Friedlin (LmjF) is a protozoan parasite whose genomic sequence has been recently elucidated. Here we have cloned, overexpressed, purified, and characterized the product of the gene from LmjF chromosome 16: LmjF16.0530, which encodes a protein with putative dihydroorotate dehydrogenase activity. Dihydroorotate dehydrogenase (DHODH) is a flavoprotein that catalyses the oxidation of L-dihydroorotate to orotate, the fourth sequential step in the de novo pyrimidine nucleotide synthesis pathway. The predicted enzyme from L. major was cloned and expressed in Escherichia coli strain BL21(DE3) as a histidine-tag fusion protein and purified to homogeneity using affinity chromatography. The final product was homogeneous in SDS-PAGE gel electrophoresis. The dihydroorotate oxidase activity has been assayed and the steady-state kinetic mechanism has been determined using fumarate as the oxidizing substrate. The catalysis by LmDHODH enzyme proceeds by a Ping-Pong Bi-Bi mechanism and the kinetic parameters Km were calculated to be 90 and 418 microM for dihydroorotate and fumarate, respectively, and Vmax was calculated to be 11 micromol min-1 mg-1. Our results confirmed that the product of the gene LmjF16.0530, whose function has previously been predicted based on homology to known proteins, can therefore be positively assigned as L. major DHODH.  相似文献   

12.
An unrecognized pentahydroxy bile alcohol has been isolated from the bile and feces of patients with cerebrotendinous xanthomatosis (CTX). Its structure, 5 β-cholestane-3 α, 7 α, 12 α, 25, 26-pentol has been deduced by spectroscopic methods and confirmed by comparison with a synthetic analog.  相似文献   

13.
Delta sleep-inducing peptide (DSIP) has been found to induce sleep as well as extra-sleep effects. Although the presence of endogenous DSIP-like material has been demonstrated, the metabolic fate of injected DSIP has not been clarified so far. A major obstacle in monitoring degradation of DSIP has been the lack of an easy method to separate DSIP from tryptophan (Trp). Cleavage of the N-terminal Trp apparently represents the first and most important step in the metabolism of the peptide. Adsorption to aluminum oxide has been found to separate the two compounds and optimal conditions for the separation are described. Quantitative determination of the degradation of DSIP in plasma or serum is now rapidly achieved. The method should help to advance metabolic studies of DSIP. Other applications such as extraction of DSIP from solutions are also possible.  相似文献   

14.
The Giemsa banding patterns of the chromosomes of 4 species of Procyonidae, 13 of Viverridae, and 6 of Felidae have been studied. The patterns have all been related to the basic felid karyotype. Each procyonid and viverrid has a distinctive karyotype, whereas some felids have indistinguishable karyotypes even when banded. Extensive interfamilial G-banding conservatism has been demonstrated, with many chromosomes being "shared" by all three families. A chromosome identification and karyotyping system for the Carnivora has been devised to facilitate comparison of data from future studies. Phylogenetic implications of the findings have been discussed.  相似文献   

15.
Thenya  Thuita 《Hydrobiologia》2001,458(1-3):107-119
Ewaso Narok Swamp, formed along the Eng'are Narok river, is located in the semi-arid part of the Laikipia District, Kenya. The area, of bushy grassland, is characterised by low rainfall (less than 750 mm annually) and episodic rivers. Before the 1970s, the dominant land use was large scale ranching and nomadic pastoralism. Since 1970, this has slowly been transformed into high density small-scale farming. There has been a strong trend towards settlement along riverine and wetland areas due to their suitability for farming and easy availability of water for cultivation. Ewaso Narok swamp has a rich species diversity of over 170 bird species, resident and migrant, over 100 plant species and it also provides an important dryland refuge for both domestic and wild animals. The swamp also provides socio-economic products such as plant matter for building. The result of its land use transformation has been ecosystem alteration, habitat modification and destruction both for wetland and rangeland species. This change has also been accompanied by escalating human–wildlife conflict. However, although this process is self-destructive, the lack of economic returns from wildlife to some extent justify the land use transformation since the communities settling here have to satisfy the basic requirements of food and shelter. This poses the challenge of the developing appropriate ways to conserve the dryland wetlands whilst attaining maximum returns for the local community.  相似文献   

16.
During the last 10–15 years significant progress has been achieved in all directions of studies of the glutathione system. A series of new enzymes involved into metabolism of glutathione has been discovered. Many of these enzymes are polyfunctional and their new activities have been recognized. The enzymes interact with hormones and signal transduction systems. Significant progress has been achieved in the studies of intracellular, intercellular and inter-organ transport. The important achievement is employment of not only selective compounds-analyzers but also gene engineering methods for identification of new functions.  相似文献   

17.
Metal nanoparticles have been studied and applied in many areas including the biomedical, agricultural, electronic fields, etc. Several products of colloidal silver are already on the market. Research on new, eco-friendly and cheaper methods has been initiated. Biological production of metal nanoparticles has been studied by many researchers due to the convenience of the method that produces small particles stabilized by protein. However, the mechanism involved in this production has not yet been elucidated although hypothetical mechanisms have been proposed in the literature. Thus, this review discusses the various mechanisms provided for the biological synthesis of metal nanoparticles by peptides, bacteria, fungi, and plants. One thing that is clear is that the mechanistic aspects in some of the biological systems need more detailed studies.  相似文献   

18.
Aquaporin-4 (AQP4), a member of the water channel family, has high water permeability and multi-functional potentiality. Although an avian AQP4 homolog has recently been identified, its overall localization is still largely unknown. This study demonstrates the presence of AQP4 in several organs of chicken by using a specific chicken AQP4 antibody. Western blot analysis has revealed two bands of chicken AQP4 (30 and 32?kDa) in the brain, proventriculus, pectoral muscle, kidney, and ureter. The brain is the primary expression site of AQP4 in chicken. Immunohistochemical analysis of the brain has shown the highest AQP4 immunoreactivity around the cerebral ventricles, blood vessels, and the Purkinje cells. In peripheral organs, AQP4-immunoreactive elements have been observed in the ureter, glandular cells of the proventriculus, sarcolemma of the pectoral muscle, and the epithelium of the ceca and the rectum. Moreover, a heavily stained network of AQP4-immunoreactive fibers has been detected within the enteric plexuses.  相似文献   

19.
《Cell biology international》2019,43(12):1523-1523
The above article, published online on 31 October 2017 in Wiley Online Library ( https://doi.org/10.1002/cbin.10907 ), has been withdrawn by agreement with the journal Editor, Sergio Schenkman, and John Wiley & Sons Ltd. The withdrawal has been agreed because the authors have not provided a signed Copyright Transfer Agreement.  相似文献   

20.
New findings of the white-toothed shrews (Crocidura spp.) from offshore islands of Vietnam are reported. The species identifications have been confirmed by the analysis of complete mitochondrial cytochrome b gene (1140 bp). Crocidura phuquocensis is the only species found in the Phu Quoc Island. Crocidura fuliginosa has been recorded from two islands of the Con Dao Archipelago (Con Son and Bai Canh). The occurrence of Crocidura fuliginosa in Vietnam has been genetically confirmed for the first time. Crocidura attenuata has been collected from the Cat Ba Island for the first time, and this finding corresponds well with the proposal that the species' distribution is confined to the north and east of the Red River only.  相似文献   

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