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191.
Shibnath Ghosal Radhey S. Srivastava Dulal C. Chatterjee Sunil K. Dutta 《Phytochemistry》1974,13(10):2247-2251
A new C27-steroidal sapogenin-peptide ester, fenugreekine, has been isolated from seeds of Trigonella foenum-graecum. On acid hydrolysis, it afforded diosgenin, yamogenin, (25R)-spirosta-3,5-diene, a mixture of three isomeric (2S,3R,4R-, 2S,3R,4S-, 2S,3S,4R-)-4-hydroxyisoleucine lactones, 4′-hydroxyisoleucyl-4-hydroxyisoleucine lactone, and a C14-dipeptide which was partially characterized. On the basis of this chemical transformation and spectral (UV, IR, PMR, MS) evidence of fenugreekine and its transformation products, the steroidal sapogenin-peptide ester is assigned structure (1). The two dipeptides also have not been encountered before in nature or prepared synthetically. The compound shows a number of interesting pharmacological and virological activities. 相似文献
192.
S. Dutta Gupta 《Biologia Plantarum》1999,42(2):297-302
The protein profile of cells of control somatic embryos was compared to that of embryos that have become selected and maintained
on 200 mM NaCl in order to detect salt inducible proteins. Two proteins (60 and 51.5 kDa) were more abundant in the selected
embryos and one protein with molecular mass 18 kDa was unique to the selected embryos. Enhanced content of 27 kDa protein
was observed in all somatic embryos indicating its involvement in the embryonal state. Similar pattern of salt inducible proteins
in selected somatic embryos and the plantlets regenerated from such embryos was found.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
193.
The 80s loop of the catalytic chain of Escherichia coli aspartate transcarbamoylase is critical for catalysis and homotropic cooperativity. 下载免费PDF全文
C. Macol M. Dutta B. Stec H. Tsuruta E. R. Kantrowitz 《Protein science : a publication of the Protein Society》1999,8(6):1305-1313
The X-ray structure of the Escherichia coli aspartate transcarbamoylase with the bisubstrate analog phosphonacetyl-L-aspartate (PALA) bound shows that PALA interacts with Lys84 from an adjacent catalytic chain. To probe the function of Lys84, site-specific mutagenesis was used to convert Lys84 to alanine, threonine, and asparagine. The K84N and K84T enzymes exhibited 0.08 and 0.29% of the activity of the wild-type enzyme, respectively. However, the K84A enzyme retained 12% of the activity of the wild-type enzyme. For each of these enzymes, the affinity for aspartate was reduced 5- to 10-fold, and the affinity for carbamoyl phosphate was reduced 10- to 30-fold. The enzymes K84N and K84T exhibited no appreciable cooperativity, whereas the K84A enzyme exhibited a Hill coefficient of 1.8. The residual cooperativity and enhanced activity of the K84A enzyme suggest that in this enzyme another mechanism functions to restore catalytic activity. Modeling studies as well as molecular dynamics simulations suggest that in the case of only the K84A enzyme, the lysine residue at position 83 can reorient into the active site and complement for the loss of Lys84. This hypothesis was tested by the creation and analysis of the K83A enzyme and a double mutant enzyme (DM) that has both Lys83 and Lys84 replaced by alanine. The DM enzyme has no cooperativity and exhibited 0.18% of wild-type activity, while the K83A enzyme exhibited 61% of wild-type activity. These data suggest that Lys84 is not only catalytically important, but is also essential for binding both substrates and creation of the high-activity, high-affinity active site. Since low-angle X-ray scattering demonstrated that the mutant enzymes can be converted to the R-structural state, the loss of cooperativity must be related to the inability of these mutant enzymes to form the high-activity, high-affinity active site characteristic of the R-functional state of the enzyme. 相似文献
194.
G. C. Sahoo S. Borthakur N. N. Dutta N. N. Dass 《Bioprocess and biosystems engineering》1999,20(2):117-125
Non-dispersive reactive extraction of cephalosporin antibiotics has been studied using hollow fiber membrane modules. Extraction as well as stripping has been studied using a pH swing procedure. Cephalosporin was extracted from an aqueous solution of cephalosporin having a pH above the pKa2 value to an organic phase containing Aliquat-336 as the extractant and n-heptane as the diluent. The solute was stripped from the loaded organic phase to another aqueous phase of pH maintained well below the pKa2 value of the cephalosporin. The extraction cum stripping relies on pH dependance of the distribution coefficient of cephalosporin in aqueous phase. Reasonably high solute recovery and mass transfer rate have been achieved in the hollow fiber module. Mass transfer performance of a single module has been evaluated and experimentally observed low value of height of transfer unit (HTU) indicates good prospect of hollow fiber membrane for the extraction duty. 相似文献
195.
Teressa Paulsen Pumoli Malapati Yoshiyuki Shibata Briana Wilson Rebeka Eki Mouadh Benamar Tarek Abbas Anindya Dutta 《Nucleic acids research》2021,49(20):11787
Extrachromosomal circular DNA (eccDNA) are present within all eukaryotic organisms and actively contribute to gene expression changes. MicroDNA (200-1000bp) are the most abundant type of eccDNA and can amplify tRNA, microRNA, and novel si-like RNA sequences. Due to the heterogeneity of microDNA and the limited technology to directly quantify circular DNA molecules, the specific DNA repair pathways that contribute to microDNA formation have not been fully elucidated. Using a sensitive and quantitative assay that quantifies eight known abundant microDNA, we report that microDNA levels are dependent on resection after double-strand DNA break (DSB) and repair by Microhomology Mediated End Joining (MMEJ). Further, repair of DSB without resection by canonical Non-Homologous End Joining (c-NHEJ) diminishes microDNA formation. MicroDNA levels are induced locally even by a single site-directed DSB, suggesting that excision of genomic DNA by two closely spaced DSB is not necessary for microDNA formation. Consistent with all this, microDNA levels accumulate as cells undergo replication in S-phase, when DNA breaks and repair are elevated, and microDNA levels are decreased if DNA synthesis is prevented. Thus, formation of microDNA occurs during the repair of endogenous or induced DNA breaks by resection-based DNA repair pathways. 相似文献
196.
Bacteriophages are the natural predators of bacteria and are available abundantly everywhere in nature. Lytic phages can specifically infect their bacterial host (through attachment to the receptor) and use their host replication machinery to replicate rapidly, a feature that enables them to kill a disease-causing bacteria. Hence, phage attachment to the host bacteria is the first important step of the infection process. It is reported in this study that the receptor could be an LPS which is responsible for the attachment of the Sfk20 phage to its host (Shigella flexneri 2a). Phage Sfk20 bacteriolytic activity was examined for preliminary optimization of phage titer. The phage Sfk20 viability at different saline conditions was conducted. The LC–MS/MS technique used here for detecting and identifying 40 Sfk20 phage proteins helped us to get an initial understanding of the structural landscape of phage Sfk20. From the identified proteins, six structurally significant proteins were selected for structure prediction using two neural network systems: AlphaFold2 and ESMFold, and one homology modeling software: Phyre2. Later the performance of these modeling systems was compared using various metrics. We conclude from the available and generated information that AlphaFold2 and Phyre2 perform better than ESMFold for predicting Sfk20 phage protein structures. 相似文献
197.
Alireza Basiri Michelle Xiao Alec McCarthy Debashis Dutta Siddappa N. Byrareddy Martin Conda-Sheridan 《Bioorganic & medicinal chemistry letters》2017,27(2):228-231
Alzheimer’s disease (AD) is a neurodegenerative disorder affecting 35 million people worldwide. A common strategy to improve the well-being of AD patients consists on the inhibition of acetylcholinesterase with the concomitant increase of the neurotransmitter acetylcholine at cholinergic synapses. Two series of unreported N-benzylpiperidines 5(a–h) and thiazolopyrimidines 9(a–q) molecules were synthesized and evaluated in vitro for their acetylcholinesterase (AChE) inhibitory activities. Among the newly synthesized compounds, 5h, 9h, 9j, and 9p displayed higher AChE enzyme inhibitory activities than the standard drug, galantamine, with IC50 values of 0.83, 0.98, and 0.73 μM, respectively. Cytotoxicity studies of 5h, 9h, 9j, 9n and 9p on human neuroblastoma cells SH-SY5Y, showed no toxicity up to 40 μM concentration. Molecular docking simulations of the active compounds 5h and 9p disclosed the crucial role of π-π-stacking in their binding interaction to the active site AChE enzyme. The presented compounds have potential as AChE inhibitors and potential AD drugs. 相似文献
198.
Point mutations in the DNA binding domain of p53 contribute to glioma progression and poor prognosis
TP53 mutations play a significant role in glioma tumorigenesis. When located in in the DNA binding domain, these mutations can perturb p53 protein conformation and its function, often culminating in altered downstream signaling. Here we describe prevalent pattern of TP53 point mutations in a cohort of 40 glioma patients and show their relevance to gliomagenesis. Point mutations in exon 5–9 of TP53 gene were detected by DNA sequencing. Possible influence of identified mutations at the function of p53 was studied computationally and correlated with the survival. Point mutations in TP53 were detected in 10 glioma samples (25%), out of which 70% were from high grade glioma. A total of 19 TP53 point mutations were identified, out of which 42% were found to be in the DNA binding region of p53. Computational analysis predicted 87.5% of these mutations to be “probably damaging”. In three patients with tumors possessing point mutations R273H, R248Q, Y163H and R175H and poor survival times, structural analysis revealed the nature of these mutations to be disruptive and associated with high risk for cancer progression. In high grade glioma, recurrent TP53 point mutations may be the key to tumor progression, thus, emphasizing their significance in gliomagenesis. 相似文献
199.
Dipanwita Sengupta Sujan Chatterjee Tania Chatterjee Kaustav Dutta Chowdhury Priya Bhowmick Udipta Chakraborti Avik Sarkar Soumosish Paul Pradip Kumar Sur Gobinda Chandra Sadhukhan 《Proceedings of the Zoological Society》2017,70(1):28-41
Oxidative stress is proposed to play a pivotal role in the development of hepatocellular carcinoma. With an accelerated metabolism cancer cells demand high reactive species accumulation to maintain their indiscriminate cell growth and proliferation. Here we wanted to see the status of reactive species in the chemically induced liver cancer. For this purpose swiss albino mice were exposed to DEN and CCl4 to develop an in vivo model of hepatocarcinoma. Depletion of cellular antioxidants regulated accretion of reactive species during the development of DEN + CCl4 induced tumor formation in hepatocytes. Currently available therapeutics for heptatocellular carcinoma is costly and coupled with certain bystander effects to the surrounding control cells. Therefore considering the antioxidant properties of SAC and berberine we treated DEN + CCl4 exposed mice after the development of liver tumor. Results effectively pointed out the usefulness of the alternative treatment with SAC and berberine in hepatoprotection. Replenishment of both enzymatic and non enzymatic antioxidant efficiently reduced accumulation of reactive species and that eventually closely associated with effective reduction in tumor number and size after drug treatment in DEN + CCl4 exposed mice. 相似文献
200.
Mandal C Dutta A Mallick A Chandra S Misra L Sangwan RS Mandal C 《Apoptosis : an international journal on programmed cell death》2008,13(12):1450-1464
Withaferin A (WA) is present abundantly in Withania somnifera, a well-known Indian medicinal plant. Here we demonstrate how WA exhibits a strong growth-inhibitory effect on several human
leukemic cell lines and on primary cells from patients with lymphoblastic and myeloid leukemia in a dose-dependent manner,
showing no toxicity on normal human lymphocytes and primitive hematopoietic progenitor cells. WA-mediated decrease in cell viability was observed through apoptosis as demonstrated by externalization of phosphatidylserine,
a time-dependent increase in Bax/Bcl-2 ratio; loss of mitochondrial transmembrane potential, cytochrome c release, caspases 9 and 3 activation; and accumulation of cells in sub-G0 region based on DNA fragmentation. A search for
the downstream pathway further reveals that WA-induced apoptosis was mediated by an increase in phosphorylated p38MAPK expression,
which further activated downstream signaling by phosphorylating ATF-2 and HSP27 in leukemic cells. The RNA interference of
p38MAPK protected these cells from WA-induced apoptosis. The RNAi knockdown of p38MAPK inhibited active phosphorylation of
p38MAPK, Bax expression, activation of caspase 3 and increase in Annexin V positivity. Altogether, these findings suggest
that p38MAPK in leukemic cells promotes WA-induced apoptosis. WA caused increased levels of Bax in response to MAPK signaling,
which resulted in the initiation of mitochondrial death cascade, and therefore it holds promise as a new, alternative, inexpensive
chemotherapeutic agent for the treatment of patients with leukemia of both lymphoid and myeloid origin.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献