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Inhibition of tyrosinase activity by metallothionein from Aspergillus nigerHossain, Abzal January 1999 (has links)
No description available.
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Identification and Activity of Monoamine Oxidase in the Orb-Weaving Spider Larinioides CornutusWilson, Rebecca J., Ahmed, Tahmina H., Rahman, Md Mahbubur, Cartwright, Brian M., Jones, Thomas C. 01 December 2020 (has links)
Monoamine oxidase (MAO) is a mitochondrial membrane-bound enzyme that catalyzes the oxidative deamination of monoamines in a wide array of organisms. While the enzyme monoamine oxidase has been studied extensively in its role in moderating behavior in mammals, there is a paucity of research investigating this role in invertebrates, where the latter utilizes this enzyme in a major pathway to degrade monoamines. There is especially a dismal lack of information on how MAO influences activity in invertebrates, particularly in account of the circadian cycle. Previous studies revealed MAO degrades serotonin and norepinephrine in arachnids, but did not investigate other critically important compounds like octopamine. Larinioides cornutus is a species of orb-weaving spider that exhibits diel fluctuations in behavior, specifically levels of aggression. The monoamines octopamine and serotonin have been shown to influence aggressive behaviors in L. cornutus, thus this species was used to investigate if MAO is a potential site of regulation throughout the day. Not only did gene expression of MAO orthologs and MAO activity fluctuate at different times of day, but the enzymatic activity was substrate-specific producing a higher level of degradation of octopamine as compared to serotonin in vitro. This study further supports evidence that MAO has an active role in monoamine inactivation in invertebrates and provides a first look at how MAO ultimately may be regulating behavior in an invertebrate.
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The Role of Extracellular Matrix Rigidity and Altered microRNA Expression In TGF-beta-Mediated Breast Cancer ProgressionTaylor, Molly Ann 12 March 2013 (has links)
No description available.
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Gene Flow and Dispersal of the Flatworm, <em>Polycelis coronata</em>: A Multiscale AnalysisMoore, Jeffrey N. 02 December 2010 (has links) (PDF)
We determined genetic variance and gene flow across multiple scales (reaches, headwater segments, and catchments) to examine the dispersal ability of the flatworm Polycelis coronata along the Wasatch Mountains of Utah. Multiple models predict patterns of genetic differentiation in stream invertebrates based on dispersal traits and the spatial connectivity of the habitat. The stream hierarchy model predicts genetic differentiation to be low and gene flow to be high between reaches nested in segments, moderate among segments within catchments, and differentiation to be highest and gene flow lowest among catchments, whereas the headwater model predicts the greatest differentiation between headwater segments. Our objective was to determine which model best described genetic patterns observed in P. coronata. Using a nested hierarchical sampling design ensured that if limitations to dispersal had an effect on genetic differentiation, we would be able to identify at what scale these processes operate. We hypothesized genetic variation would be small within headwater segments and reach maximum levels between headwater segments with no increase in differentiation with increasing distance between headwater patches or between drainages. We do not expect high dispersal along the stream network or across the terrestrial environment (actively or passively).We generated DNA sequence data (mitochondrial COI) from 50 sites nested within 24 segments, which were nested in four adjacent catchments. We identified 134 haplotypes from 506 individuals using a 763 bp fragment of mtDNA. Genetic patterns did not conform to the SH model. Evidence from one drainage (Provo River) was consistent with the headwater model. However, high differentiation within sites suggested that the genetic patterns we uncovered may be representative of high ancestral polymorphism among pre-fragmented populations that were historically widespread. Large effective population sizes and no evidence of bottleneck events suggest incomplete lineage cannot be discounted as an explanation of high differentiation at the smallest scales.
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Synthesis Of Biocompatible Antioixidant Polymer Coated Cerium Oxide Nanoparticles, Its Oxidase Like Behavior And Cellular UptakeAsati, Atul 01 January 2009 (has links)
Cerium oxide nanoparticles have been widely used for various applications such as catalytic converters for automobile exhaust, ultraviolet absorber, and electrolyte in fuel cells. Most recently, cerium oxide nanoparticles (nanoceria) have been employed as potent free-radical scavengers with neuroprotective, radioprotective, and anti-inflammatory properties. These properties of cerium oxide nanoparticles can open new vistas in medicine and biotechnology. The present study utilizes the water-based-wet-chemical method to synthesize biocompatible,stable and highly monodisperse polymer coated cerium oxide nanoparticles. Polymer coated cerium oxide nanoparticles possess all the characteristics of the uncoated cerium oxide nanoparticles. These nanoparticles were found to be effective as pH-dependent antioxidant giving cytoprotection to normal cell lines against hydrogen peroxide and nitric oxide radical but not to cancer cells. Moreover, cerium oxide nanoparticle also exhibits unique oxidase-like activity at acidic pH oxidizing a series of organic compound without the need of hydrogen peroxide. Based on these results, we have designed an immunoassay in which folate-conjugated cerium oxide nanoparticles provide dual functionality by binding to folate expressing cancer cells and facilitating detection by catalytic oxidation of sensitive colorimetric substrates (dyes). Finally, we have shown that the polymer coated cerium oxide nanoparticles shows distinct toxicity depending upon their subcellular localization based on uptake studies using DiI loaded cerium oxide nanoparticles. In these results, we have found that cerium oxide nanoparticles entrapped into lysosomes are more toxic as opposed to when they are localized in the cytoplasm.Overall we propose that the polymer coated cerium oxide nanoparticles displays selective antioxidant property, oxidase-like activity, and cytotoxicity to biological systems depending upon its pH environment.
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Interaction of phthalazines with molybdenum hydroxylases. Phthalazine and its 1-substituted derivatives as substrates, inhibitors and inducers of aldehyde oxidase and xanthine oxidase, both in vitro and in vivo.Johnson, Christine January 1983 (has links)
The interaction of the 2,3-diazanaphthalene, phthalazine and its
1-substituted derivatives with the molybdenum hydroxylases, aldehyde
oxidase and xanthine oxidase, has been investigated both in vivo and
/Ok in vitro.
Metabolic studies, carried out by treating rabbits with both cold
and
14C-labelled
phthalazine, have shown that this compound is extensively
metabolised in vivo, the major metabolite being a glucuronide conjugate.
Very little unchanged phthalazine or its molybdenum hydroxylase
mediated oxidation product 1-hydroxyphthalazine were excreted in the
urine.
Pretreatment of rabbits with phthalazine or 1-hydroxyphthalazine
had no effect upon the activity of the microsomal monooxygenases but
caused a significant increase in the specific activities of both
aldehyde oxidase and xanthine oxidase.
Determination of the molybdenum content of purified aldehyde
oxidase fractions using electrothermal atomic absorption spectroscopy
has confirmed that an increase in the molybdenum content of the enzyme
fraction accompanies the increase in activity.
A qualitative assessment of purified aldehyde oxidase fractions
using iso-electric focusing has indicated that this enzyme may be
composed of 2 or 3 active variants and following pretreatment with
either phthalazine or 1-hydroxyphthalazine a further band of enzyme
activity is apparent on the electropherogram.
The Km value for phthalazine is significantly reduced with enzyme
prepared from phthalazine treated rabbits, indicating that a form of the
enzyme with a high affinity for phthalazine may have been induced.
1-Hydrazinophthalazine (Hydralazine) and two other hydrazine
substituted N-heterocycles, endralazine and 1-hydrazinoisoquinoline have
been shown to exert a potent progressive inhibition of aldehyde oxidase
in vitro, effective only in the presence of substrate, but are inactive
towards xanthine oxidase.
In addition, administration of hydralazine to rabbits results in a
significant reduction in liver aldehyde oxidase activity. Investigations
into the interaction of some of the metabolites of hydralazine with
aldehyde oxidase in vitro suggest that hydralazine is also the
inhibiting species in vivo. / The Ransom Fellowship awarded by The Pharmaceutical Society of Great Britain,
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Specificity of aldehyde oxidase towards N-heterocyclic cations. Oxidation of quinolinium and related cations by aldehyde oxidase in vitro; the isolation of two products formed simultaneously from a single substrate.Taylor, Susan M. January 1984 (has links)
Aldehyde oxidase catalysed oxidation of various quinolinium and
related cations has been studied in vitro. Oxidation products were
identified by comparison of their spectral and chromatographic
characteristics with those of authentic compounds. The N-heterocyclic
cations and quinolones used required synthesis.
Incubation of N-methylquinolinium, N-methyl-7,8-benzoquinolinium
and N-phenylquinolinium yielded the corresponding 2- and 4-quinolones
simultaneously. The ratio of 2- to 4-quinolone formation was found to
be species dependent; the proportion of 4-quinolone was greater with
guinea pig enzyme than with rabbit enzyme.
Incubation of N-methyl-4-methylquinolinium, N-methyl-4-phenylquinolinium
and N-methylphenanthridinium produced the expected 2-quinolones.
Cations substituted adjacent to the ring nitrogen, i. e. N-methyl-2-
methylquinolinium, N-methyl-2-phenylquinolinium and N-phenyl-2-phenylquinolinium,
were oxidised to the corresponding 4-quinolones.
Kinetic constants were determined spectrophotometrically. The Km
values obtained with rabbit enzyme ranged from 1.6 x 10-3 M for N-methylquinolinium
to <10-5 M for N-phenyl-2-phenylquinolinium. Quaternary
compounds were found to be better substrates than their non-quaternary
counterparts, except for N-methylisoquinolinium and N-methylphenanthridinium.
In general, guinea pig aldehyde oxidase was shown to have a greater affinity
for N-heterocyclic cations than rabbit enzyme.
The substrate binding site has been discussed in the light of the
results outlined below.
Oxidation of N-methyl-4-phenylquinolinium (to the 2-quinolone) was
competitively inhibited by N-methyl-2-phenylquinolinium (which yields the
4-quinolone), indicating that both these cations interact at the same
active site. The ratio of 2- to 4-quinolone production from N-methylquinolinium
was constant under various conditions, including purification
of the enzyme but changed at high pH or in the presence of N-methylphenanthridinium.
Inhibition studies indicated that both quaternary and non-quaternary
compounds act at the same site on the enzyme. Km and Vmax values for
phthalazine, N-methyl-2-phenylquinolinium and N-methylquinolinium were
determined over the pH range 5.4 to 10.2. In each case, results indicated
that the enzyme has an ionisable group at the active site with a pK ca. 8.
Aldehyde oxidase was shown to catalyse the dehydrogenation of the
pseudobases 3,4-dihydro-4-hydroxy-3-methyl-2-quinazolinone and 3,4-dihydro-
4-hydroxy-3-methylquinazoline.
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Biocatalysis of tyrosinase in chloroform medium using selected phenolic substratesTse, Mara. January 1996 (has links)
No description available.
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Electrochemical Evaluation of Plasma Membrane Cholesterol in Live Cells and Mouse TissuesJiang, Dechen 06 June 2008 (has links)
No description available.
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Regulation of MONOCYTE NADPH OXIDASE:Role of Pattern Recognition ReceptorsElsori, Deena H. 22 September 2009 (has links)
No description available.
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