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71.
B. K. Sharma P. Singh Susheela Sharma 《Journal of enzyme inhibition and medicinal chemistry》2013,28(5):601-607
The antagonistic activities of derivatives of spiroethyl phenyl(substituted)piperazine at the 5-HT1A and adrenergic α1d receptors is quantitatively analyzed employing physicochemical and structural parameters. The derived correlation equation revealed that a substituent, other than 2-CH3 in the phenyl ring, having higher molar refraction, MR, and a substituent producing higher positive field effect at the 3-position are beneficial in increasing the binding affinity at the 5-HT1A receptor. In addition, a less hydrophobic substituent at the 4-position is also helpful in augmenting the binding affinity. The 5-R substituents which have higher MR values, however, elicit a detrimental effect. Two disubstituted compounds which are not present in the original data-set and have higher theoretical binding affinities are designed from the correlation equation. These compounds consisting of 2-OCH(CH3)2, 3-Cl and 2-C3H7, 3-Cl in the phenyl ring, have theoretical pKi values 10.57 and 10.12 respectively. For the adrenergic α1d receptor, a less bulky group at the 3-position with 5-Cl (or simply a 3-Cl) is advantageous in increasing the binding affinity. Likewise, a substituent exhibiting a less negative resonance effect at the 4-position and the substituent with low polarizability and showing more a negative resonance effect at the 5-position are suitable for enhancement of the binding affinity. The analysis provides the grounds for rationalizing substituent selection in designing better potency antagonists in the series. 相似文献
72.
Dan Wu Yanyan Han Qin Wei Yanfang Zhao Kexia Mao Yanyan Cai Ru Li Yuxue Dai 《Luminescence》2011,26(6):629-633
Based on the inhibition effect of transferrin (Tf) on the reaction of the luminol–hydrogen peroxide (H2O2) chemiluminescence (CL) system, catalysed by meso‐tetra‐(3‐methoxyl‐4‐hydroxyl) phenyl manganese porphyrin (MnP) as a mimetic enzyme of peroxides, a sensitive flow‐injection CL method has been developed for the determination of Tf in an alkaline medium. The CL reaction was carefully investigated by examining the variations of reaction conditions. Under optimum conditions, the linear range for the determination of transferrin was 0.04–20.0 μg/mL and the detection limit was 1.62 ng/mL. This proposed method was sensitive, convenient and simple, and has been successfully applied to the determination of transferrin in a serum sample. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
73.
Cold stress causes rapid but differential changes in properties of plasma membrane H-ATPase of camelina and rapeseed 总被引:1,自引:0,他引:1
Camelina (Camelina sativa) and rapeseed (Brassica napus) are well-established oil-seed crops with great promise also for biofuels. Both are cold-tolerant, and camelina is regarded to be especially appropriate for production on marginal lands. We examined physiological and biochemical alterations in both species during cold stress treatment for 3 days and subsequent recovery at the temperature of 25 °C for 0, 0.25, 0.5, 1, 2, 6, and 24 h, with particular emphasis on the post-translational regulation of the plasma membrane (PM) H+-ATPase (EC3.6.3.14). The activity and translation of the PM H+-ATPase, as well as 14-3-3 proteins, increased after 3 days of cold stress in both species but recovery under normal conditions proceeded differently. The increase in H+-ATPase activity was the most dramatic in camelina roots after recovery for 2 h at 25 °C, followed by decay to background levels within 24 h. In rapeseed, the change in H+-ATPase activity during the recovery period was less pronounced. Furthermore, H+-pumping increased in both species after 15 min recovery, but to twice the level in camelina roots compared to rapeseed. Protein gel blot analysis with phospho-threonine anti-bodies showed that an increase in phosphorylation levels paralleled the increase in H+-transport rate. Thus our results suggest that cold stress and recovery in camelina and rapeseed are associated with PM H+-fluxes that may be regulated by specific translational and post-translational modifications. 相似文献
74.
Guadalupe Martel-Gallegos Griselda Casas-Pruneda Filiberta Ortega-Ortega Sergio Sánchez-Armass Jesús Alberto Olivares-Reyes Becky Diebold Patricia Pérez-Cornejo Jorge Arreola 《Biochimica et Biophysica Acta (BBA)/General Subjects》2013
Background
Activation of ATP-gated P2X7 receptors (P2X7R) in macrophages leads to production of reactive oxygen species (ROS) by a mechanism that is partially characterized. Here we used J774 cells to identify the signaling cascade that couples ROS production to receptor stimulation.Methods
J774 cells and mP2X7-transfected HEK293 cells were stimulated with Bz-ATP in the presence and absence of extracellular calcium. Protein inhibitors were used to evaluate the physiological role of various kinases in ROS production. In addition, phospho-antibodies against ERK1/2 and Pyk2 were used to determine activation of these two kinases.Results
ROS generation in either J774 or HEK293 cells (expressing P2X7, NOX2, Rac1, p47phox and p67phox) was strictly dependent on calcium entry via P2X7R. Stimulation of P2X7R activated Pyk2 but not calmodulin. Inhibitors of MEK1/2 and c-Src abolished ERK1/2 activation and ROS production but inhibitors of PI3K and p38 MAPK had no effect on ROS generation. PKC inhibitors abolished ERK1/2 activation but barely reduced the amount of ROS produced by Bz-ATP. In agreement, the amount of ROS produced by PMA was about half of that produced by Bz-ATP.Conclusions
Purinergic stimulation resulted in calcium entry via P2X7R and subsequent activation of the PKC/c-Src/Pyk2/ERK1/2 pathway to produce ROS. This signaling mechanism did not require PI3K, p38 MAPK or calmodulin.General significance
ROS is generated in order to kill invading pathogens, thus elucidating the mechanism of ROS production in macrophages and other immune cells allow us to understand how our body copes with microbial infections. 相似文献75.
Lockamy EL Cornea RL Karim CB Thomas DD 《Biochemical and biophysical research communications》2011,(3):35044-392
We have used functional co-reconstitution of purified sarcoplasmic reticulum (SR) Ca2+-ATPase (SERCA) with phospholamban (PLB), its inhibitor in the heart, to test the hypothesis that loss-of-function (LOF) PLB mutants (PLBM) can compete with wild-type PLB (PLBW) to relieve SERCA inhibition. Co-reconstitution at varying PLB-to-SERCA ratios was conducted using synthetic PLBW, gain-of-function mutant I40A, or LOF mutants S16E (phosphorylation mimic) or L31A. Inhibitory potency was defined as the fractional increase in KCa, measured from the Ca2+-dependence of ATPase activity. At saturating PLB, the inhibitory potency of I40A was about three times that of PLBW, while the potency of each of the LOF PLBM was about one third that of PLBW. However, there was no significant variation in the apparent SERCA affinity for these four PLB variants. When SERCA was co-reconstituted with mixtures of PLBW and LOF PLBM, inhibitory potency was reduced relative to that of PLBW alone. Furthermore, FRET between donor-labeled SERCA and acceptor-labeled PLBW was decreased by both (unlabeled) LOF PLBM. These results show that LOF PLBM can compete both physically and functionally with PLBW, provide a rational explanation for the partial success of S16E-based gene therapy in animal models of heart failure, and establish a powerful platform for designing and testing more effective PLBM targeted for gene therapy of heart failure in humans. 相似文献
76.
Rong Qiang Liu Guo Hua Ding Jian Ling Li Hua Jie Feng Wen Ying He Lu Yong Wu 《Luminescence》2020,35(1):129-137
A new compound, ethyl 5‐phenyl‐2‐(p‐tolyl)‐2H‐1,2,3‐triazole‐4‐carboxylate was successfully introduced and synthesized as a novel rhodamine B derivative named REPPC, and characterized by 1H nuclear magnetic resonance (NMR), 13C NMR, and high resolution mass spectrometry (HRMS). It showed an obvious fluorescence and UV–visible light absorption enhancement towards Hg2+ ion without interference from common metal ions in N,N‐dimethylformamide–H2O (pH 7.4). The spirolactam ring moiety of rhodamine in REPPC was converted to the open‐ring form generating a 1:1 complex with the intervention of a mercury ion, verified by electrospray ionization‐mass spectroscopy testing and density functional theory calculation. REPPC was used to visualize the level of mercury ions in living HeLa cells with encouraging results. 相似文献
77.
Olga Kopach Ilya Kruglikov Tatyana Pivneva Nana Voitenko Alexei Verkhratsky Nataliya Fedirko 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》2011,1813(10):1740-1748
The salivary acinar cells have unique Ca2+ signaling machinery that ensures an extensive secretion. The agonist-induced secretion is governed by Ca2+ signals originated from the endoplasmic reticulum (ER) followed by a store-operated Ca2+ entry (SOCE). During tasting and chewing food a frequency of parasympathetic stimulation increases up to ten fold, entailing cells to adapt its Ca2+ machinery to promote ER refilling and ensure sustained SOCE by yet unknown mechanism. By employing a combination of fluorescent Ca2+ imaging in the cytoplasm and inside cellular organelles (ER and mitochondria) we described the role of mitochondria in adjustment of Ca2+ signaling regime and ER refilling according to a pattern of agonist stimulation. Under the sustained stimulation, SOCE is increased proportionally to the degree of ER depletion. Cell adapts its Ca2+ handling system directing more Ca2+ into mitochondria via microdomains of high [Ca2+] providing positive feedback on SOCE while intra-mitochondrial tunneling provides adequate ER refilling. In the absence of an agonist, the bulk of ER refilling occurs through Ca2+-ATPase-mediated Ca2+ uptake within subplasmalemmal space. In conclusion, mitochondria play a key role in the maintenance of sustained SOCE and adequate ER refilling by regulating Ca2+ fluxes within the cell that may represent an intrinsic adaptation mechanism to ensure a long-lasting secretion. 相似文献
78.
79.
Degenhardt T Saramäki A Malinen M Rieck M Väisänen S Huotari A Herzig KH Müller R Carlberg C 《Journal of molecular biology》2007,372(2):341-355
The nuclear receptors peroxisome proliferator-activated receptors (PPARs) are known for their critical role in the metabolic syndrome. Here, we show that they are direct regulators of the family of pyruvate dehydrogenase kinase (PDK) genes, whose products act as metabolic homeostats in sensing hunger and satiety levels in key metabolic tissues by modulating the activity of the pyruvate dehydrogenase complex. Mis-regulation of this tightly controlled network may lead to hyperglycemia. In human embryonal kidney cells we found the mRNA expression of PDK2, PDK3 and PDK4 to be under direct primary control of PPAR ligands, and in normal mouse kidney tissue Pdk2 and Pdk4 are PPAR targets. Both, treatment of HEK cells with PPARbeta/delta-specific siRNA and the genetic disruption of the Pparbeta/delta gene in mouse fibroblasts resulted in reduced expression of Pdk genes and abolition of induction by PPARbeta/delta ligands. These findings suggest that PPARbeta/delta is a key regulator of PDK genes, in particular the PDK4/Pdk4 gene. In silico analysis of the human PDK genes revealed two candidate PPAR response elements in the PDK2 gene, five in the PDK3 gene and two in the PDK4 gene, but none in the PDK1 gene. For seven of these sites we could demonstrate both PPARbeta/delta ligand responsiveness in context of their chromatin region and simultaneous association of PPARbeta/delta with its functional partner proteins, such as retinoidXreceptor, co-activator and mediator proteins and phosphorylated RNA polymerase II. In conclusion, PDK2, PDK3 and PDK4 are primary PPARbeta/delta target genes in humans underlining the importance of the receptor in the control of metabolism. 相似文献
80.
Shrivastava S Chattopadhyay A 《Biochemical and biophysical research communications》2007,356(3):705-710
Ergosterol is an evolutionary precursor of cholesterol and is the major sterol present in lower eukaryotes. Although detailed biophysical characterization of the effect of cholesterol on membranes is well documented, the effect of ergosterol on the organization and dynamics of membranes is still at a very early stage. We have monitored the effect of cholesterol and ergosterol on the dynamic properties of both fluid (POPC) and gel (DPPC) phase membranes utilizing fluorescent reporter probes pyrene and TMA-DPH. These results show, for the first time, the important differences on the effect of cholesterol and ergosterol in short-range ordering (reported by TMA-DPH) and long-range dynamics (reported by pyrene). In addition, pyrene vibronic peak intensity ratio provides information on polarity of the microenvironment experienced by the probe. These novel results are relevant in the context of membrane domains in ergosterol-containing organisms such as Drosophila which maintain a low level of sterol compared to higher eukaryotes. 相似文献