16 research outputs found
Catalase activity of oxygenase domain of rat neuronal nitric oxide synthase. Evidence for product formation from L-arginine
AbstractNitric oxide synthases (NOSs) catalyze the formation of nitric oxide from L-arginine. We purified the heme containing, tetrahydrobiopterin-free, oxygenase domain of rat neuronal nitric oxide synthase (nNOSox) overexpressed in Escherichia coli. We found catalase activity in nNOSox. This is significant because H2O2 may also be a product of nitric oxide synthases. We found H2O2 assisted product formation from N-hydroxy-L-arginine and even from L-arginine both in the presence and in absence of tetrahydrobiopterin. We propose how heme moiety of the oxygenase domain alone is sufficient to carry out both steps of the NOS catalysis
Protective effect of kombucha tea against tertiary butyl hydroperoxide induced cytotoxicity and cell death in murine hepatocytes
511-524Kombucha
(KT), a fermented black tea (BT), is known to have many
beneficial properties. In the present study, antioxidant property of KT has
been investigated against tertiary butyl hydroperoxide (TBHP) induced
cytotoxicity using murine hepatocytes. TBHP, a reactive oxygen species inducer,
causes oxidative stress resulting in organ pathophysiology. Exposure to TBHP
caused a reduction in cell viability, increased membrane leakage and disturbed
the intra-cellular antioxidant machineries in hepatocytes. TBHP exposure disrupted mitochondrial membrane potential and induced apoptosis as evidenced
by flow cytometric analyses. KT treatment, however, counteracted the changes in
mitochondrial membrane potential and prevented apoptotic cell death of the
hepatocytes. BT treatment also
reverted TBHP induced hepatotoxicity, however KT was found to be more
efficient. This may be due to the formation of antioxidant molecules like
D-saccharic acid-1,4-lactone (DSL) during fermentation process and are absent
in BT. Moreover, the radical scavenging activities of KT were found to be
higher than BT. Results of the study showed that KT has the potential to
ameliorate TBHP induced oxidative insult and cell death in murine hepatocytes
more effectively than BT
Enhanced biofilm formation and melanin synthesis by the oyster settlement-promoting <i>Shewanella colwelliana</i> is related to hydrophobic surface and simulated intertidal environment
<div><p>A direct relationship between biofilm formation and melanogenesis in <i>Shewanella colwelliana</i> with increased oyster recruitment is already established. Previously, <i>S. colwelliana</i> was grown in a newly patented biofilm-cultivation device, the conico-cylindrical flask (CCF), offering interchangeable hydrophobic/hydrophilic surfaces. Melanization was enhanced when <i>S. colwelliana</i> was cultivated in a hydrophobic vessel compared with a hydrophilic vessel. In the present study, melanogenesis in the CCF was positively correlated with increased architectural parameters of the biofilm (mean thickness and biovolume obtained by confocal laser scanning microscopy) and melanin gene (<i>melA</i>) expression observed by densitometry. Niche intertidal conditions were mimicked in a process operated in an ultra-low-speed rotating disk bioreactor, which demonstrated enhanced biofilm formation, melanogenesis, exopolysaccharide synthesis and <i>melA</i> gene expression compared with a process where 12-h periodic immersion and emersion was prevented. The wettability properties of the settling plane as well as intermittent wetting and drying, which influenced biofilm formation and <i>melA</i> expression, may affect oyster settlement in nature.</p></div
Isolation of an unusual metabolite 2-allyloxyphenol from a marine actinobacterium, its biological activities and applications
A marine actinobacterium isolated from the Bay of
Bengal, India and previously found to be producing an
antimicrobial and cytotoxic terpenoid was further investigated
for antimicrobial metabolites. The bacterium was preliminarily
identified as a new species of the genus Streptomyces
(strain MS1/7). The cell-free culture broth was extracted
with n-butanol and purified using silica gel column
chromatography and high-performance liquid chromatography.
Molecular characterization was done using ESI mass,
IR and 1H and 13C NMR spectrometry. 2-Allyloxyphenol
(MW 150; C9H10O2), a synthetic drug and chemical
intermediate, was obtained as a natural product for the first
time. Serendipitous natural occurrence provided new insights
into the synthetic molecule. 2-Allyloxyphenol was found to
be inhibitory to 21 bacteria and three fungi in the minimum range 0.2–1.75 mg mL−1 determined by agar dilution
method. 2-Allyoxyphenol possesses strong antioxidant property
(IC50 22 μg mL−1, measured by 1, 1-diphenyl-2-picryl
hydrazyl scavenging activity). Hydroxyl and allyloxy groups
in 2-allyloxyphenol were responsible for antimicrobial and
antioxidant activities. 2-Allyloxyphenol has marked resemblance
to smoky aroma and is two to three times more active
as an antimicrobial than some commercial smoke-flavour
compounds. Absence of hemolytic toxicity, potential carcinogenicity,
cytotoxicity and reports of toxic reactions in
literature suggest possible application of 2-allyloxyphenol as
a food preservative and an oral disinfectant.
Keywords Sundarbans . 2-Allyloxyphenol . Streptomyces .
Antimicrobial . Antioxidant . Smoke flavou
Formation of Nitric Oxide Synthase−Iron(II) Nitrosoalkane Complexes: Severe Restriction of Access to the Iron(II) Site in the Presence of Tetrahydrobiopterin
The Structure of Nitric Oxide Synthase Oxygenase Domain and Inhibitor Complexes
The nitric oxide synthase oxygenase domain (NOS_(ox)) oxidizes arginine to synthesize the cellular signal and defensive cytotoxin nitric oxide (NO). Crystal structures determined for cytokine-inducible NOS_(ox) reveal an unusual fold and heme environment for stabilization of activated oxygen intermediates key for catalysis. A winged β sheet engenders a curved α-β domain resembling a baseball catcher's mitt with heme clasped in the palm. The location of exposed hydrophobic residues and the results of mutational analysis place the dimer interface adjacent to the heme-binding pocket. Juxtaposed hydrophobic O_2- and polarL-arginine–binding sites occupied by imidazole and aminoguanidine, respectively, provide a template for designing dual-function inhibitors and imply substrate-assisted catalysis
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Histidine-containing amphiphilic peptide-based non-cytotoxic hydrogelator with antibacterial activity and sustainable drug release
A histidine-based amphiphilic peptide (P) has been found to form an injectable transparent hydrogel in phosphate buffer solution over a pH range from 7.0 to 8.5 with an inherent antibacterial property. It also formed a hydrogel in water at pH = 6.7. The peptide self-assembles into a nanofibrillar network structure which is characterized by high-resolution transmission electron microscopy, field-emission scanning electron microscopy, atomic force microscopy, small-angle X-ray scattering, Fourier-transform infrared spectroscopy, and wide-angle powder X-ray diffraction. The hydrogel exhibits efficient antibacterial activity against both Gram-positive bacteria Staphylococcus aureus (S. aureus) and Gram-negative bacteria Escherichia coli (E. coli). The minimum inhibitory concentration of the hydrogel ranges from 20 to 100 μg/mL. The hydrogel is capable of encapsulation of the drugs naproxen (a non-steroidal anti-inflammatory drug), amoxicillin (an antibiotic), and doxorubicin, (an anticancer drug), but, selectively and sustainably, the gel releases naproxen, 84% being released in 84 h and amoxicillin was released more or less in same manner with that of the naproxen. The hydrogel is biocompatible with HEK 293T cells as well as NIH (mouse fibroblast cell line) cells and thus has potential as a potent antibacterial and drug releasing agent. Another remarkable feature of this hydrogel is its magnification property like a convex lens