Search results for "Erich"
showing 10 items of 805 documents
Ridge-line optimal detector
2000
Image processing techniques have seen many developments in recent years. Starting from the pioneering work of Canny, Deriche developed a second order recursive filter capable of detecting stepped contours. However, there are other contour shapes that those filters struggle to detect. We describe a new optimal filter sensu Canny for detecting ridge-line contours. This is a third order recursive and even filter. It is dependent on three parameters by which detection accuracy is adjusted. The results obtained by applying this filter to (possibly noise- affected) images are compared with those in the work by Ziou. © 2000 Society of Photo-Optical Instrumentation Engineers. (S0091-3286(00)00706-6)
Differentiation of DctA and DcuS function in the DctA/DcuS sensor complex ofEscherichia coli: function of DctA as an activity switch and of DcuS as t…
2014
Summary The C4-dicarboxylate responsiveness of the sensor kinase DcuS is only provided in concert with C4-dicarboxylate transporters DctA or DcuB. The individual roles of DctA and DcuS for the function of the DctA/DcuS sensor complex were analysed. (i) Variant DctA(S380D) in the C4-dicarboxylate site of DctA conferred C4-dicarboxylate sensitivity to DcuS in the DctA/DcuS complex, but was deficient for transport and for growth on C4-dicarboxylates. Consequently transport activity of DctA is not required for its function in the sensor complex. (ii) Effectors like fumarate induced expression of DctA/DcuS-dependent reporter genes (dcuB–lacZ) and served as substrates of DctA, whereas citrate ser…
Decipher the mechanisms of protein conformational changes induced by nucleotide binding through free-energy landscape analysis: ATP binding to Hsp70.
2013
ATP regulates the function of many proteins in the cell by transducing its binding and hydrolysis energies into protein conformational changes by mechanisms which are challenging to identify at the atomic scale. Based on molecular dynamics (MD) simulations, a method is proposed to analyze the structural changes induced by ATP binding to a protein by computing the effective free-energy landscape (FEL) of a subset of its coordinates along its amino-acid sequence. The method is applied to characterize the mechanism by which the binding of ATP to the nucleotide-binding domain (NBD) of Hsp70 propagates a signal to its substrate-binding domain (SBD). Unbiased MD simulations were performed for Hsp…
Interaction ofEscherichia colihemolysin with biological membranes
2001
Escherichia coli hemolysin (HlyA) is a membrane-permeabilizing protein belonging to the family of RTX-toxins. Lytic activity depends on binding of Ca2(+) to the C-terminus of the molecule. The N-terminus of HlyA harbors hydrophobic sequences that are believed to constitute the membrane-inserting domain. In this study, 13 HlyA cysteine-replacement mutants were constructed and labeled with the polarity-sensitive fluorescent probe 6-bromoacetyl-2-dimethylaminonaphthalene (badan). The fluorescence emission of the label was examined in soluble and membrane-bound toxin. Binding effected a major blue shift in the emission of six residues within the N-terminal hydrophobic domain, indicating inserti…
Inducible Genetic Code Expansion in Eukaryotes
2020
Abstract Genetic code expansion (GCE) is a versatile tool to site‐specifically incorporate a noncanonical amino acid (ncAA) into a protein, for example, to perform fluorescent labeling inside living cells. To this end, an orthogonal aminoacyl‐tRNA‐synthetase/tRNA (RS/tRNA) pair is used to insert the ncAA in response to an amber stop codon in the protein of interest. One of the drawbacks of this system is that, in order to achieve maximum efficiency, high levels of the orthogonal tRNA are required, and this could interfere with host cell functionality. To minimize the adverse effects on the host, we have developed an inducible GCE system that enables us to switch on tRNA or RS expression whe…
Removal of Escherichia coli from Saturated Sand Columns Supplemented with Hydrochar Produced from Maize
2014
Despite numerous studies on hydrochar use, its application in water treatment for pathogen removal remains unexplored. In this study, we evaluated the efficiency of hydrochar produced from crop residue of maize for water treatment by determining Escherchia coli breakthrough from sand columns supplemented with hydrochar. To enhance the adsorptive capacity, raw hydrochar was activated by 1 mol L⁻¹ KOH at room temperature. The experiments conducted in a 10-cm sand bed with 1.5% (w/w) activated and raw hydrochar supplements, not activated by KOH, showed 93 and 72% of E. coli removal efficiencies, respectively. Activation of KOH not only enhanced the E. coli removal but also increased the streng…
Cell inactivation and membrane damage after long-term treatments at sub-zero temperature in the supercooled and frozen states.
2008
The survival of cells subjected to cooling at sub-zero temperature is of paramount concern in cryobiology. The susceptibility of cells to cryopreservation processes, especially freeze-thawing, stimulated considerable interest in better understanding the mechanisms leading to cell injury and inactivation. In this study, we assessed the viability of cells subjected to cold stress, through long-term supercooling experiments, versus freeze-thawing stress. The viability of Escherichia coli, Saccharomyces cerevisiae, and leukemia cells were assessed over time. Supercooled conditions were maintained for 71 days at -10 degrees C, and for 4 h at -15 degrees C, and -20 degrees C, without additives or…
Three-dimensional structure of hepatitis B virus core particles determined by electron cryomicroscopy
1994
Human hepatitis B virus core protein expressed in E. coli assembles into two sizes of particle. We have determined their three-dimensional structures by electron cryomicroscopy and image processing. The large and small particles correspond to triangulation number T = 4 and T = 3 dimer clustered packings, containing 240 and 180 protein subunits, respectively. The local packing of subunits is very similar in the two sizes of particle and shows holes or channels through the shell. The native viral core particle packages RNA and is active in reverse transcription to DNA. The holes we observe may provide access for the necessary small molecules. Shells assembled from the intact core protein cont…
Alkane oxidation by a carboxylate-bridged dimanganese(III) complex
2001
[EN] A new manganese( III) oxamato dimer possesing an unprecedented Mn-2(mu -O2CR)(mu -OH2. . .O2CR) core has been synthesised, structurally and magnetically characterised, and used as a catalyst for the oxidation of alkanes to alcohols and ketones by (BuO2H)-O-t and O-2 in CH2Cl2 at rt.