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81.
82.
83.
Kaushik Ghosh Rajagopal Chattopadhyaya 《Journal of biomolecular structure & dynamics》2013,31(4):557-567
Abstract The circular dichroism spectra of three different purified carboxy terminal fragments 93–236, 112–236 and 132–236 of the bacteriophage γ cI repressor have been measured and compared with those of the intact repressor and the amino terminal fragment 1–92. All three carboxy terminal fragments contain mostly β-strands and loops, a minor helix content increasing with the size of the fragment, showing that the 93–131 region previously called a hinge is structured. Fourier transformed infrared spectra also showed that fragment 93–236 contains α-helices, β-sheets and turns but fragment 132–236 contains no detectable α-helix, only β-sheets and turns. Papain is known to cleave the γ repressor, but it is shown here that it cannot cleave the operator-bound repressor dimer. For the 132–236 fragment, both the wt and the SN228 mutant previously shown to be dimerization defective in the intact, gave similar dimerization properties as investigated by HPLC at 2 to 100 µM protein concentration, with a KD of 13.2 µM and 19.1 µM respectively. The papain cleavage for wt and SN228 proceed at equal rates for the first cleavage at 92–93; however, the subsequent cleavages are faster for SN228. The three Cys residues in the 132–236 fragment were found to be unreactive upon incubation with DTNB, indicating the thiol sulfur atoms are buried in the repressor carboxy terminal domain. Denaturation of the 132–236 fragment studied by tryptophan fluorescence shows two transitions centered at 1.5 M and 4.5 M of urea. 相似文献
84.
Background
Endocytosis is a key regulator of growth factor signaling pathways. Recent studies showed that the localization to endosomes of intracellular mediators of growth factor signaling may be required for their function. Although there is substantial evidence linking endocytosis and growth factor signaling in cultured cells, there has been little study of the endosomal localization of signaling components in intact tissues or organs. 相似文献85.
Ramansu Goswami Suprabhat Mukherjee Vipin Singh Rana Dhira Rani Saha Rajagopal Raman Pratap Kumar Padhy 《Geomicrobiology journal》2013,30(1):17-26
Bengal Basin is known for severe arsenic contamination. In the present study, we have isolated six bacteria from the arsenic contaminated surface water of Bengal Basin. 16S rDNA sequence analysis identified them as Microbacterium oleivorans, Acinetobacter soli, Acinetobacter venetianus, Acinetobacter junii, Acinetobacter baumannii, Acinetobacter calcoaceticus. All the isolates possess arsenic accumulation potential and high molecular weight plasmid (>10 kb). PCR amplification indicated the presence of arsenic-resistance genes (arsB and aoxB) either in the genome or plasmid or in both in the isolated bacteria (except in Acinetobacter venetianus). Exposure to arsenic affected bacterial growth and induced alteration in cytoplasmic membrane integrity. 相似文献
86.
87.
Mark A. Seefeld Hong Lin Joerg Holenz Dave Downie Brian Donovan Tingting Fu Kishore Pasikanti Wei Zhen Matthew Cato Khuram W. Chaudhary Pat Brady Tania Bakshi Dwight Morrow Sridharan Rajagopal Swapan Kumar Samanta Naveena Madhyastha Bharathi Mohan Kuppusamy Robert W. Dougherty Yasuji Matsuoka 《Bioorganic & medicinal chemistry letters》2018,28(23-24):3793-3797
Neuronal voltage-gated potassium channels, KV7s, are the molecular mediators of the M current and regulate membrane excitability in the central and peripheral neuronal systems. Herein, we report novel small molecule KV7 openers that demonstrate anti-seizure activities in electroshock and pentylenetetrazol-induced seizure models without influencing Rotarod readouts in mice. The anti-seizure activity was determined to be proportional to the unbound concentration in the brain. KV7 channels are also expressed in the bladder smooth muscle (detrusor) and activation of these channels may cause localized undesired effects. Therefore, the impact of individual KV7 isoforms was investigated in human detrusor tissue using a panel of KV7 openers with distinct activity profiles among KV7 isoforms. KCNQ4 and KCNQ5 mRNA were highly expressed in detrusor tissue, yet a compound that has significantly reduced activity on homomeric KV7.4 did not reduce detrusor contraction. This may suggest that the homomeric KV7.4 channel plays a less significant role in bladder contraction and further investigation is needed. 相似文献
88.
Saiful Alom Siddique Thangavel Tamilselvan Manikkannan Vishnupriya Elumalai Balamurugan 《Neurochemical research》2018,43(6):1171-1181
A number of neurotransmitter systems have been implicated in contributing to the pathology of mood disorders, including those of dopamine (DA), serotonin (5-HT), norepinephrine (NE) and γ-aminobutyric acid (GABA). Rapid eye movement sleep deprivation (REMSD) alters most of the neurotransmitters, which may have adverse behavioural changes and other health consequences like mania and other psychiatric disorders. The exact role of REMSD altered neurotransmitter levels and the manner in which emerging consequences lead to mania-like behaviour is poorly understood. Thus, we sought to verify the levels of neurotransmitter changes after 48, 72 and 96 h of REMSD induced mania-like behaviour in mice. We performed modified multiple platform (MMP) method of depriving the REM sleep and one group maintained as a control. To measure the hyperactivity through locomotion, exploration and behavioural despair, we performed the Open Field Test (OFT) and the Forced Swim Test (FST). Quantitative determinations of DA, 5-HT, NE and GABA concentrations in four distinct brain regions (cerebral cortex, hippocampus, midbrain, and pons) were determined by the spectrofluorimetric method. These experiments showed higher locomotion and increased swimming, struggling/climbing and decreased mobility among REMSD animals as well as disrupted concentrations of the majority of the studied neurotransmitters during REMSD. Our study indicated that REMSD results in mania-like behaviour in mice and associated disruption to neurotransmitter levels, although the exact mechanisms by which these take place remain to be determined. 相似文献
89.
Dhilna Malayil Boby Jose Arunaksharan Narayanankutty Varsha Ramesh Rajakrishnan Rajagopal Ahmed Alfarhan 《Saudi Journal of Biological Sciences》2021,28(11):6040-6044
Azima tetracantha, a traditional medicinal plant included in the order Brassicales and family Salvadoraceae, is widely used as a dietary supplement in folklore medicines. The plant is also used for the treatment of rheumatism, diarrhea and other inflammatory disorders. The present investigation focused on the phytochemical composition, radical scavenging, reducing potential and anti-proliferative activities of the A. tetracantha leaves. Quantitative estimation of the polyphenols and flavonoids revealed significantly elevated levels in the methanol extract. Corroborating with this, methanol extract exhibited higher in vitro anti-radical scavenging effect against 2,2-diphenyl-1- picrylhydrazyl (34.14 ± 2.19 μg/mL), and hydrogen peroxide (44.96 ± 1.77 μg/mL), as well as ferric reducing properties (58.24 ± 6.98 μg/mL). The methanolic extract also showed strong lipoxygenase (71.42 ± 6.36 μg/mL) and nitric oxide inhibitory activities (94.23 ± 8.11 μg/mL). Cytotoxic activity against MCF7 cells was found to be higher (IC50= 37.62 ± 2.94 μg/mL), than that of MDAMB231 cells (IC50= 69.11 ± 5.02 μg/mL). The qPCR-based analysis indicated dose-dependent increase in the expression of the pro-apoptotic genes such as executioner caspases and apoptotic protease activating factor-1. Overall, the results indicated the possible use of methanol extract of A. tetracantha leaves as a chain-breaking antioxidant molecule and are capable of inhibiting inflammatory enzymes and the proliferative potential of breast cancer cells. 相似文献
90.
Sriram Rajagopal Thomas L. Moskal Hongmei Wang Subhas Chakrabarty 《Journal of cellular physiology》1999,178(3):296-303
Transforming growth factorβ1 (TGFβ1) elicits a multitude of cellular responses from the epithelial-derived human colon cancer Moser cells. TGFβ1 induces the expression of laminin and fibronectin, and previous studies show that the induction of fibronectin is functionally associated with the regulation of carcinoembryonic antigen (CEA) expression by TGFβ1 (Huang and Chakrabarty, 1994, J Biol Chem 269:28764–28768). In this study we constructed antisense laminin chain-specific expression vectors and determined their efficacy in blocking the expression and the induction of the large multichain laminin molecule by TGFβ1. We also determined the functional role of laminin in several TGFβ1-mediated responses: growth inhibition, downmodulation of anchorage-independent growth, and cellular invasion. Expression of either antisense laminin chain A, B1, or B2 RNA resulted in a downmodulation of endogenous laminin mRNA expression and blocked the induction of laminin protein by TGFβ1 without affecting the induction of other adhesion molecules such as fibronectin or CEA. It is concluded that antisense RNA directed to only one of the laminin chains was sufficient to disrupt the induction of the complex laminin molecule in quite a specific manner. Expression of antisense laminin RNA downregulated cellular adhesion to extracellular matrix (ECM) laminin and blocked the ability of TGFβ1 to upmodulate adhesion to ECM laminin. Expression of antisense laminin RNA, however, did not alter the downregulating effect of TGFβ1 on cellular proliferation, anchorage-independent growth, or cellular invasion, suggesting that the induction of laminin did not play a significant functional role in these TGFβ1-mediated cellular responses. It is likely that other adhesion pathways may be involved in mediating the action of TGFβ1 in this cell line. J. Cell. Physiol. 178:296–303, 1999. © 1999 Wiley-Liss, Inc. 相似文献