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301.
Korkmaz A Oter S Sadir S Topal T Uysal B Ozler M Ay H Akin A 《Neurochemical research》2008,33(1):160-166
Hyperbaric oxygen (HBO) is known to cause oxidative stress in several organs and tissues. Due to its high rate of blood flow
and oxygen consumption, the brain is one of the most sensitive organs to this effect. The present study was performed to elucidate
the relation of HBO exposure time to its oxidative effects in rats’ brain cortex tissue. For this purpose, 49 rats were randomly
divided into five groups. Except the control group, study groups were subjected to three atmospheres HBO for 30, 60, 90, and
120 min. Their cerebral cortex layer was taken immediately after exposure and used for analysis. Thiobarbituric acid reactive
substances (TBARS), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and nitrate–nitrite (NOX) levels were determined. TBARS and SOD levels were found to increase in a time-dependent manner. GSH-Px activity reflected
an inconsistent course. NOX levels were found to be increased only in the 120 min exposed group. The results of this study suggests that HBO induced
oxidative effects are strongly related with exposure time. 相似文献
302.
We have determined the plasma concentrations of copper, zinc, copper/zinc ratio, and carbonic anhydrase activity in horses
infected with Babesia equi. The study was conducted in 14 horses with the disease and 10 healthy animals that served as controls. The infection was
confirmed by the clinical manifestations of the disease and by Giemsa staining of thin blood smears showing the parasites
inside red blood cells. The horses with piroplasmosis had lower plasma levels of zinc, elevated copper, and increased activity
of carbonic anhydrase. Consequently, the copper/zinc ratio was also higher than in the healthy controls. 相似文献
303.
Sanders C Turkarslan S Lee DW Onder O Kranz RG Daldal F 《The Journal of biological chemistry》2008,283(44):29715-29722
Cytochrome c maturation (Ccm) is a post-translational and post-export protein modification process that involves ten (CcmABCDEFGHI and CcdA or DsbD) components in most Gram-negative bacteria. The absence of any of these components abolishes the ability of cells to form cytochrome c, leading in the case of Rhodobacter capsulatus to the loss of photosynthetic proficiency and respiratory cytochrome oxidase activity. Based on earlier molecular genetic studies, we inferred that R. capsulatus CcmF, CcmH, and CcmI interact with each other to perform heme-apocytochrome c ligation. Here, using functional epitope-tagged derivatives of these components coproduced in appropriate mutant strains, we determined protein-protein interactions between them in detergent-dispersed membranes. Reciprocal affinity purification as well as tandem size exclusion and affinity chromatography analyses provided the first biochemical evidence that CcmF, CcmH, and CcmI associate stably with each other, indicating that these Ccm components form a membrane-integral complex. Under the conditions used, the CcmFHI complex does not contain CcmG, suggesting that the latter thio-reduction component is not always associated with the heme ligation components. The findings are discussed with respect to defining the obligatory components of a minimalistic heme-apocytochrome c ligation complex in R. capsulatus. 相似文献
304.
Conducting-state properties of the KcsA potassium channel from molecular and Brownian dynamics simulations. 总被引:6,自引:0,他引:6
The mechanisms underlying transport of ions across the potassium channel are examined using electrostatic calculations and three-dimensional Brownian dynamics simulations. We first build open-state configurations of the channel with molecular dynamics simulations, by pulling the transmembrane helices outward until the channel attains the desired interior radius. To gain insights into ion permeation, we construct potential energy profiles experienced by an ion traversing the channel in the presence of other resident ions. These profiles reveal that in the absence of an applied field the channel accommodates three potassium ions in a stable equilibrium, two in the selectivity filter and one in the central cavity. In the presence of a driving potential, this three-ion state becomes unstable, and ion permeation across the channel is observed. These qualitative explanations are confirmed by the results of three-dimensional Brownian dynamics simulations. We find that the channel conducts when the ionizable residues near the extracellular entrance are fully charged and those near the intracellular side are partially charged. The conductance increases steeply as the radius of the intracellular mouth of the channel is increased from 2 A to 5 A. Our simulation results reproduce several experimental observations, including the current-voltage curves, conductance-concentration relationships, and outward rectification of currents. 相似文献
305.
Serdar Burmaoğlu Hatice Seçinti Erkan Mozioğlu Ahmet C. Gören Ramazan Altundaş Hasan Seçen 《Journal of enzyme inhibition and medicinal chemistry》2017,32(1):878-884
Four multicaulin and miltirone-like phenanthrene derivatives were synthesised and evaluated as antituberculosis agents. The crucial step of the synthesis was Pschorr coupling of 4-(3-isopropyl-4-methoxyphenyl)-2-(2-aminophenyl)ethane (13) to give 2-isopropyl-3-methoxy-9,10-dihydrophenanthrene (9) and 4-isopropyl-3-methoxy-9,10-dihydrophenanthrene (9a). Compound 9 was converted to multicaulin and miltirone-like phenanthrene derivatives by further reactions. The best antituberculosis activity was exhibited by 2-isopropylphenanthrene-3-ol (11). 相似文献
306.
307.
308.
Glucose-6-phosphate dehydrogenase is the key regulatory enzyme of the pentose phosphate pathway and one of the products of this enzyme; NADPH has a critical role in the defence system against the free radicals. In this study, glucose-6-phosphate dehydrogenase from lamb kidney cortex kinetic properties is examined. The purification procedure is composed of two steps after ultracentrifugation for rapid and easy purification: 2', 5'-ADP Sepharose 4B affinity and DEAE Sepharose Fast Flow anion exchange chromatography. Previously, we used this procedure for the purification of glucose-6-phosphate dehydrogenase from bovine lens. The double reciprocal plots and product inhibition studies showed that the enzyme obeys 'Ordered Bi Bi' mechanism: K(m NADP+)K(m G-6-P) and K(i G-6-P) (dissociation constant of the enzyme--G-6-P complex) were found to be 0.018 +/- 0.002, 0.039 +/- 0.006 and 0.029 +/- 0.005 mM, respectively, by using nonlinear regression analysis. The enzyme was stable at 4 degrees C for a week. 相似文献
309.
Aromatase in endometriosis and uterine leiomyomata 总被引:7,自引:0,他引:7
Bulun SE Imir G Utsunomiya H Thung S Gurates B Tamura M Lin Z 《The Journal of steroid biochemistry and molecular biology》2005,95(1-5):57-62
Endometrial tissue from uterine disease-free women does not exhibit aromatase activity. In contrast, aromatase enzyme activity and mRNA levels are readily detectable in endometriosis. PGE2 stimulates both aromatase expression and activity in endometriotic stromal cells via promoter II region of the aromatase gene. This results in local production of estradiol, which induces PGE2 formation and establishes a positive feedback cycle. This mechanism seems to contribute to continuous production of estradiol and PGE2. Aromatase mRNA levels and enzyme activity are also present in uterine leiomyomata that are estrogen-dependent benign tumors of the myometrium. Successful treatment of endometriosis and uterine leiomyomata using aromatase inhibitors by recent pilot trials underscores the clinical significance of these molecular studies. 相似文献
310.
Tamura M Sebastian S Yang S Gurates B Ferrer K Sasano H Okamura K Bulun SE 《The Journal of biological chemistry》2002,277(29):26208-26216