Search results for "bacteria."
showing 10 items of 4757 documents
The fnr Gene of Bacillus licheniformis and the Cysteine Ligands of the C-Terminal FeS Cluster
1998
Many of the O2-responsive gene regulators of bacteria are members of the fumarate nitrate reductase-cyclic AMP receptor protein family of transcriptional regulators (12, 13, 15, 17) with predicted structures similar to those of the cyclic AMP receptor protein (11). The Fnr (stands for fumarate nitrate reductase regulator) protein from Escherichia coli (FnrEc) controls the expression of a variety of genes, mainly of anaerobic respiration and metabolism (5, 13). It contains a N-terminal cluster of three essential cysteine residues which are supposed to bind together with Cys122 a [4Fe 4S]2+ cluster which is required for O2 sensing (4, 7, 8, 10, 16). A wide variety of gram-negative bacteria co…
The Myristoylated Alanine-Rich C-Kinase Substrate (MARCKS) is Sequentially Phosphorylated by Conventional, Novel and Atypical Isotypes of Protein Kin…
1995
The myristoylated alanine-rich C-kinase substrate (MARCKS) is the major protein kinase C (PKC) substrate in many cell types including fibroblasts and brain cells. Here we describe the phosphorylation of MARCKS and the site specificity for different PKC isotypes. Conventional (c)PKC beta 1, novel (n)PKC delta and nPKC epsilon efficiently phosphorylated the MARCKS protein in vitro. The Km values were extremely low, reflecting a high affinity between kinases and substrate. The apparent affinity of nPKC delta (Km = 0.06 microM) was higher than that of nPKC epsilon and cPKC beta 1 (Km = 0.32 microM). The rate of substrate phosphorylation was inversely correlated with affinity and decreased in th…
Solvothermal Synthesis of Molybdenum–Tungsten Oxides and Their Application for Photoelectrochemical Water Splitting
2018
Molybdenum and tungsten oxides are of interest as semiconductors for the production of clean and sustainable energy. Here we show that synergistic effects arising from a combination of noncrystalli...
Molybdenum blue: Binding to collagen fibres and microcrystal formation
2005
Collagen fibres have been shown by transmission electron microscopy to progressively bind the polyoxomolybdate ring-complex, termed molybdenum blue. Nucleation of cuboidal molybdenum blue microcrystals occurs on the surface of the collagen fibres, leading eventually to extensive coating of the fibres with microcrystals.
Mössbauer spectroscopy on the reaction center of Rhodopseudomonas viridis
1992
Proteins called “reaction centers” (RC) can be isolated from many photosynthetic bacteria. They have one non-heme iron in a quinone acceptor region. The RC of Rhodopseudomonas viridis contains an additional tightly bound tetra-heme cytochrome c subunit. The electronic configuration of both cytochrome and the non-heme iron has been studied in the crystallized protein by Mossbauer spectroscopy at different redox potentials, pH-values, and with an addition of o-phenanthroline. At high potentials (Eh=+500mV) all heme irons are in the low spin Fe3+-state, and at low potential (Eh=−150mV) they are low spin Fe2+ with the same Mossbauer parameters for all hemes independent of pH. Redox titrations c…
Truncated recombinant light harvesting complex II proteins are substrates for a protein kinase associated with photosystem II core complexes
1998
AbstractPrevious studies directed towards understanding phosphorylation of the chlorophyll a/b binding proteins comprising light harvesting complex II (LHC II) have concentrated on a single phosphorylation site located close to the N-terminus of the mature proteins. Here we show that a series of recombinant pea Lhcb1 proteins, each missing an N-terminal segment including this site, are nevertheless phosphorylated by a protein kinase associated with a photosystem II core complex preparation. An Lhcb1 protein missing the first 58 amino acid residues is not, however, phosphorylated. The results demonstrate that the LHC II proteins are phosphorylated at one or more sites, the implications of wh…
Water Fluxes in Polymeric Membranes for Desalination via Membrane Distillation
2010
Membrane distillation is an emerging technique for seawater desalination. Hydrophobic polymeric membranes are used to separate the solute‐free water vapour from the hot solution. Vapour fluxes of commercial polymeric membranes were measured in various conditions, i.e. natural and forced convection and vacuum. Vapour fluxes were also predicted with models and compared with experimentals. Higher fluxes were recorded in vacuum conditions.
Role of glutathione in the formation of the active form of the oxygen sensor FNR ([4Fe-4S]·FNR) and in the control of FNR function
2000
The oxygen sensor regulator FNR (fumarate nitrate reductase regulator) of Escherichia coli is known to be inactivated by O2 as the result of conversion of a [4Fe-4S] cluster of the protein into a [2Fe-2S] cluster. Further incubation with O2 causes loss of the [2Fe-2S] cluster and production of apoFNR. The reactions involved in cluster assembly and reductive activation of apoFNR isolated under anaerobic or aerobic conditions were studied in vivo and in vitro. In a gshA mutant of E. coli that was completely devoid of glutathione, the O2 tension for the regulatory switch for FNR-dependent gene regulation was decreased by a factor of 4–5 compared with the wild-type, suggesting a role for glutat…
Mössbauer Spectroscopy on Photosynthetic Bacteria: Investigation of Reaction Centers of Rhodopseudomonas Viridis
1990
Crystals of 57Fe enriched reaction centers have been investigated by Mossbauer spectroscopy. The cytochrome irons are in the low spin ferric state. The non-heme iron of the electron accepting side is partly ferrous high spin and partly ferrous low spin (or ferric high spin). Under the conditions of the experiment sodium ascorbate reduces only one cytochrome iron into the ferrous low spin state. Membrane bound proteins become flexible at higher temperatures than proteins with a hydrophilic surface. They are also less flexible, at least up to temperatures of about 250 K.
ChemInform Abstract: Synthesis and anti-Staphylococcal Activity of New Halogenated Pyrroles Related to Pyrrolomycins F.
2008
The chemical synthesis of new halogenated pyrroles related to pyrrolomycins F is described and the anti-staphylococcal activity compared. The replacement of 4′-bromo atom of parent compounds with two chloro atoms at 3′ and 5′ position increase the antibacterial activity against a reference strain of S. aureus.