Search results for "bacteri"
showing 10 items of 5466 documents
Why Are Some Enzymes Dimers? Flexibility and Catalysis in Thermotoga maritima Dihydrofolate Reductase
2019
[Image: see text] Dihydrofolate reductase from Thermotoga maritima (TmDFHFR) is a dimeric thermophilic enzyme that catalyzes the hydride transfer from the cofactor NADPH to dihydrofolate less efficiently than other DHFR enzymes, such as the mesophilic analogue Escherichia coli DHFR (EcDHFR). Using QM/MM potentials, we show that the reduced catalytic efficiency of TmDHFR is most likely due to differences in the amino acid sequence that stabilize the M20 loop in an open conformation, which prevents the formation of some interactions in the transition state and increases the number of water molecules in the active site. However, dimerization provides two advantages to the thermophilic enzyme: …
Biological control ofBotrytis cinereacausing grey mould disease of grapevine and elicitation of stilbene phytoalexin (resveratrol) by a soil bacterium
1998
Botrytis cinerea Pers. was found to be highly pathogenic to the grapevine plant, producing the characteristic grey mould symptoms within 7 days of inoculation on vitroplants. A bacterial strain, isolated from soil, belonging to the genus Bacillus was found to be an antagonist of this disease causing fungus. The fungal attack on the grapevine acts as an elicitor to the production of phytoalexines like resveratrol. This compound was also formed when the leaves of the grapevine vitroplants were inoculated with the bacteria alone, and this activity was enhanced when a mixture of the pathogen and the antagonist bacteria was applied. Since resveratrol in wine is considered to be beneficial to hum…
From Food Map to FODMAP in Irritable Bowel Sindrome.
2016
Irritable bowel syndrome (IBS) is one of the most common gastrointestinal diseases in the general population, with a prevalence ranging from 12 % to 30 %, mainly affecting younger patients (i.e., <50 years of age) and women [1]. As in other chronic functional gastrointestinal disorders, abdominal discomfort or pain, abnormal bowel habits, and often bloating and abdominal distension are the main clinical features. Their diagnosis is based on symptom patterns (i.e., the Rome III criteria), which also allow categorization in diarrhea-predominant (D-IBS), constipation-predominant (C-IBS), mixed diarrhea and constipation (M-IBS), and unclassified (U-IBS) IBS [2]. Symptom severity ranges from tol…
Identification of Gip as a novel phage-encoded gyrase inhibitor protein featuring a broad activity profile
2021
AbstractBacteriophages represent a powerful source for the identification of novel antimicrobial proteins. In this study, a screening of small cytoplasmic proteins encoded by the CGP3 prophage of Corynebacterium glutamicum, resulted in the identification of the novel gyrase-inhibiting protein Cg1978 (Gip), which shows a direct interaction with the gyrase subunit A (GyrA). In vitro supercoiling assays further suggest a stabilization of the cleavage complex by Gip. Overproduction of Gip in C. glutamicum resulted in a severe growth defect as well as an induction of the SOS response. The cells adapted to gip overexpression by increasing expression levels of gyrAB and by reducing topA expression…
Icosahedral dsDNA Bacterial Viruses with an Internal Membrane
2008
The icosahedral double-stranded DNA bacteriophages containing an internal membrane belong to two families, the Tectiviridae and the Corticoviridae. Members of the Tectiviridae have a linear dsDNA genome (e.g., PRD1) and those of the Corticoviridae have a circular genome (the only example being PM2). The DNA is covered by a membrane which is in turn covered by a protein capsid. The infection cycle begins when spikes on the capsid recognize the host cell receptor and the virus starts the delivery of the genome into the cell cytoplasm. The replication of the virus genome occurs in the cytoplasm. The members of the Tectiviridae may be virulent or temperate; PM2 is virulent. Virulent bacteriopha…
Determination of aminoglycoside and macrolide antibiotics in meat by pressurized liquid extraction and LC-ESI-MS
2010
A simple method for the simultaneous determination of dihydrostreptomycin, spectinomycin, spiramycin, streptomycin, tilmicosin, and tylosin in meat has been developed using pressurized liquid extraction and LC-triple quadrupole MS (LC-ESI-MS/MS). The pressurized liquid extraction operational parameters were optimized and no protein precipitating and fat removing steps were required. A gradient HPLC separation was developed with ion-pair mobile phases consisting of aqueous 1 mM heptafluorobutyric acid water and methanol. Protonated molecules were used as precursor ions for CID. Data acquisition under MS/MS was achieved by applying multiple reaction monitoring of three fragment ion transition…
Antibakterielle Wirkstoffe, 6. Mitt.1) 2,4-Unsymmetrisch dialkylierte Pyrimido[1,2-a]benzimidazole
1982
Durch Kondensation von 2-Aminobenzimidazol (1) mit 2,4-Hexandion (2a) entsteht das Isomerenpaar 3a/3b, mit 6-Methyl-2,4-heptandion (2b) das Isomerengemisch 3c/3d, wahrend mit 1-Phenyl-2,4-pentandion (2c) die Isomere 3e und 3f gebildet werden. Die Trennung der Isomere ist durch Saulenchromatographie, die Strukturfestlegung auf spektroskopischem Wege, moglich. 2-Imino-2H-s-triazino[2,1-b]benzoxazol weist antibakterielle Wirksamkeit auf. Antibacterial Drugs, VI: 2,4-Unsymmetrically Dialkylated Pyrimido[1,2-α]benzimidazoles Condensation of 2-aminobenzimidazole (1) with 2,4-hexanedione (2a) leads to the pair of isomers 3a/3b. Condensation with 6-methyl-2,4-heptanedione (2b) yields the isomers 3c…
Bis- and trisporphyrin bio-inspired models for bacterial antennas and photosystems
2011
This review presents the synthetic aspects and photophysical properties of trimeric systems constructed with a first unit consisting of a cofacial porphyrin and then of another porphyrin attached as a side arm. Two scenarios are dealt with. The first one is the case where the three chromophores are different, called donor 1–donor 2–acceptor, specifically where the cofacial fragment is composed of donor 1 and donor 2, and the side arm is the acceptor. They are considered as models for the apo-proteins used in the LH II (light harvesting device) in the purple photosynthetic bacteria. The second one is the case where the chromophores of the cofacial bisporphyrin residue are identical and are …
Morphological Characterisation of Bacterial Cellulose-Starch Nanocomposites
2008
Acetobacter sp. growing medium was modified in order to produce bacterial cellulose (BC) nanocomposites using a bottom-up technique that allowed starch to be introduced into the cellulose network. The BC-starch mats were hot-pressed to obtain nanocomposites sheets. Morphological characterisation was carried out using Atomic Force Microscopy and Environmental Scanning Electron Microscopy. The images obtained from microscopy were then processed using image analysis. Network properties, such as mesh size and fibre orientation were characterised. Fracture surfaces of these new nanocomposites were analysed.
Assembly of iron oxide nanosheets at the air-water interface by leucine-histidine peptides
2021
The fabrication of inorganic nanomaterials is important for a wide range of disciplines. While many purely inorganic synthetic routes have enabled a manifold of nanostructures under well-controlled conditions, organisms have the ability to synthesize structures under ambient conditions. For example, magnetotactic bacteria, can synthesize tiny ‘compass needles’ of magnetite (Fe3O4). Here, we demonstrate the bio-inspired synthesis of extended, self-supporting, nanometer-thin sheets of iron oxide at the water–air interface through self-assembly using small histidine-rich peptides.