4,543 research outputs found

    A long and complex enhancer activates transcription of the gene coding for the highly abundant immediate early mRNA in murine cytomegalovirus

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    Using the simian virus 40 "enhancer trap" approach, we have identified a transcription enhancer located just upstream of the major immediate early gene of murine cytomegalovirus. This enhancer has several striking properties. (.) Together with the enhancer ofhuman cytomegalovirus, it is the strongest transcription enhancer found to date. (ö) It is an extremely long enhancer, spanning >700 base pairs. (ÜI) It consists of a rather complex pattern of sequence repeats, the longest of which is 181 base pairs. Also, several types of short sequence motifs are scattered throughout the enhancer in monomeric, heterodimeric, or homodimeric (palindromic) form. These motifs have been identified to be components of other enhancers and promoters, and they are presumably binding sites for specific nuclear factors. Our analysis suggests that enhancers are composed of a modular arrangement of short conserved sequence motifs and that enhancer strength is correlated with the redundancy of these motifs

    Validation of a two-parameter quantitative structure–activity relationship as a legitimate tool for rational re-design of horseradish peroxidase

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    Previously reported rates of reaction between six mutant strains of the enzyme horseradish peroxidase (HRP) and a test substrate, 2-methoyxpyhenol, were found to correlate with characteristic binding distances computed using molecular simulation. The correlation ( R 2  = 0.86) bears out a working hypothesis that, based on a quantitative structure–activity relationship (QSAR) we had previously developed for HRP, reductions in binding distances between the HRP enzyme and any selected substrate mediate increased enzyme reactivity towards that substrate. The results validate the use of QSAR as a quantitative means for formulating enzyme mutations designed to achieve enhanced HRP reactivity towards compounds of specific interest. Biotechnol. Bioeng. 2007; 98: 295–299. © 2007 Wiley Periodicals, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/56109/1/21419_ftp.pd

    Beyond deficiency:Potential benefits of increased intakesof vitamin K for bone and vascular health

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    Vitamin K is wellknown for its role in the synthesisof a number of blood coagulationfactors.During recent years vitaminK-dependent proteins werediscovered to be of vital importancefor bone and vascular health.Recommendations for dietary vitaminK intake have been made onthe basis of the hepatic requirementsfor the synthesis of bloodcoagulation factors.Accumulatingevidence suggests that the requirementsfor other functions thanblood coagulation may be higher.This paper is the result of a closedworkshop (Paris,November 2002)in which a number of Europeanvitamin K experts reviewed theavailable data and formulated theirstandpoint with respect to recommendeddietary vitamin K intakeand the use of vitamin K-containingsupplements

    Local thermodynamical equilibrium and the equation of state of hot, dense matter created in Au+Au collisions at AGS

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    Local kinetic and chemical equilibration is studied for Au+Au collisions at 10.7 AGeV in the microscopic Ultrarelativistic Quantum Molecular Dynamics model (UrQMD). The UrQMD model exhibits dramatic deviations from equilibrium during the high density phase of the collision. Thermal and chemical equilibration of the hadronic matter seems to be established in the later stages during a quasiisentropic expansion, observed in the central reaction cell with volume 125 fm3. For t > 10 fm/c the hadron energy spectra in the cell are nicely reproduced by Boltzmann distributions with a common rapidly dropping temperature. Hadron yields change drastically and at the late expansion stage follow closely those of an ideal gas statistical model. The equation of state seems to be simple at late times: P = 0.12 Epsilon. The time evolution of other thermodynamical variables in the cell is also presented

    3',5'-Cyclic Adenosine Monophosphate- and Ca2+-Calmodulin-Dependent Endogenous Protein Phosphorylation Activity in Membranes of the Bovine Chromaffin Secretory Vesicles: Identification of Two Phosphorylated Components as Tyrosine Hydroxylase and Protein Kinase Regulatory Subunit Type II

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    Abstract: Membranes of the secretory vesicles from bovine adrenal medulla were investigated for the presence of the endogenous protein phosphorylation activity. Seven phosphoprotein bands in the molecular weight range of 250,000 to 30,000 were observed by means of the sodium dodecyl sulphate electrophoresis and autoradiography. On the basis of the criteria of molecular weight, selective stimulation of the phosphorylation by cyclic AMP (as compared with cyclic GMP) and immunoprecipitation by specific antibodies, band 5 (molecular weight 60,300) was found to represent the phosphorylated form of the secretory vesicle-bound tyrosine hydroxylase. The electrophoretic mobility, the stimulatory and inhibitory effects of cyclic AMP in presence of Mg2+ and Zn,2+ respectively, and immunoreactivity toward antibodies showed band 6 to contain two forms of the regulatory subunits of the type II cyclic AMP-dependent protein kinase, distinguishable by their molecular weights (56,000 and 52,000, respectively). Phosphorylation of band 7 (molecular weight 29,800) was stimulated about 2 to 3 times by Ca2+ and calmodulin in the concentration range of both agents believed to occur in the secretory tissues under physiological conditions

    Correlation of humic substance trihalomethane formation potential and adsorption behavior to molecular weight distribution in raw and chemically treated waters

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    The molecular weight distributions (MWDs) of several commercially prepared humic and fulvic acids and organic matter present in natural waters were analyzed by gel chromatography. The responses of these substances to treatment by alum coagulation, lime softening, and activated carbon adsorption were also analyzed, as were their trihalomethane formation potentials before and after each treatment. The treatability characteristics and trihalomethane formation properties of the different organic substances were then related to their respective MWDs. Differences in the MWDs were found to effect differences in the behavior of lumped parameter measures of organic matter (such as TOC) with respect to the several treatment operations. The treatments in turn were observed to alter the MWDs of the organic substances as well as their phenomenological behavior in subsequent process operations.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26722/1/0000272.pd
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