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81.
Ganguly Shreeparna Ghosh Gourab Ghosh Sanatan Purohit Arnab Chaudhuri Rituparna Kundu Das Sampa Chakraborti Dipankar 《Plant Cell, Tissue and Organ Culture》2020,142(3):493-504
Plant Cell, Tissue and Organ Culture (PCTOC) - Major biotic and abiotic stresses have led to the reduction of chickpea productivity, creating a strong barrier for its utilization as major food... 相似文献
82.
Bhattacherjee A Chakraborti AS 《International journal of biological macromolecules》2011,48(1):202-209
We studied structural modifications of metmyoglobin (Mb) after short-term (6 days) and long-term (30 days) glycation by fructose (fructation). Fructation caused gradual changes in the structure of the protein with respect to increased absorbance at 280 nm, enhanced fluorescence emission (with excitation at 285 nm), increased surface accessible tryptophan residues and reduced α-helix content and change in tertiary structure. However, long-term fructation changed Mb to oxymyoglobin (MbO2), as demonstrated by different spectroscopic (absorption, fluorescence, circular dichroic and electron paramagnetic resonance) studies and trifluoperazine-induced oxygen release experiment. Fructation appeared to modify Arg139 to arg-pyrimidine, which exhibited antioxidative activity and might be involved in the conversion of met (Fe3+) to oxy (Fe2+) form of myoglobin. 相似文献
83.
Tamta H Kalra S Thilagavathi R Chakraborti AK Mukhopadhyay AK 《Biochemistry. Biokhimii?a》2007,72(2):170-177
Xanthine oxidase-catalyzed hydroxylation reactions of the anticancer drug 6-mercaptopurine (6-MP) and its analog 2-mercaptopurine (2-MP) as well as 6-thioxanthine (6-TX) and 2-thioxanthine (2-TX) have been studied using UV-spectroscopy, high pressure liquid chromatography, photodiode array, and liquid chromatography-based mass spectral analysis. It is shown that 6-MP and 2-MP are oxidatively hydroxylated through different pathways. Enzymatic hydroxylation of 6-MP forms 6-thiouric acid in two steps involving 6-TX as the intermediate, whereas 2-MP is converted to 8-hydroxy-2-mercaptopurine as the expected end product in one step. Surprisingly, in contrast to the other thiopurines, enzymatic hydroxylation of 2-MP showed a unique hyperchromic effect at 264 nm as the reaction proceeded. However, when 2-TX is used as the substrate, it is hydroxylated to 2-thiouric acid. The enzymatic hydroxylation of 2-MP is considerably faster than that of 6-MP, while 6-TX and 2-TX show similar rates under identical reaction conditions. The reason why 2-MP is a better substrate than 6-MP and how the chemical nature and position of the functional groups present on the thiopurine substrates influence xanthine oxidase activity are discussed. 相似文献
84.
Elham Amini Jens V. Andersen Barnali Chakraborti Artem V. Diuba Tatsiana G. Dubouskaya Eric Ehrke Andiara Espindola de Freitas Guilherme Braga de Freitas Rafaella A. Gonçalves Deepali Gupta Richa Gupta Sharon R. Ha Isabel A. Hemming Minal Jaggar Emil Jakobsen Punita Kumari Navya Lakkappa Ashley P. L. Marsh Jessica Mitlöhner Yuki Ogawa Ramesh Kumar Paidi Felipe C. Ribeiro Ahmad Salamian Suraiya Saleem Sorabh Sharma Joana M. Silva Shripriya Singh Kunjbihari Sulakhiya Tesfaye Wolde Tefera Behnam Vafadari Anuradha Yadav Reiji Yamazaki Constanze I. Seidenbecher 《Journal of neurochemistry》2019,151(2):139-165
85.
Kiran K. Thumburu Radha K. Dhiman Rakesh K. Vasishta Anuradha Chakraborti Roger F. Butterworth Elizabeth Beauchesne Paul Desjardins Sandeep Goyal Navneet Sharma Ajay Duseja Yogesh Chawla 《Journal of neurochemistry》2014,128(5):617-627
In vitro and in vivo studies have suggested that reduced astrocytic uptake of neuronally released glutamate, alterations in expression of glial fibrillary acidic protein (GFAP) and aquaporin‐4 (AQP‐4) contribute to brain edema in acute liver failure (ALF). However, there is no evidence to date to suggest that these alterations occur in patients with ALF. We analyzed the mRNA expression of excitatory amino acid transporters (EAAT‐1, EAAT‐2), GFAP, and AQP‐4 in the cerebral cortex obtained at autopsy from eight patients with ALF and from seven patients with no evidence of hepatic or neurological disorders by real‐time PCR, and protein expression was assessed using immunoblotting and immunohistochemistry. We demonstrated a significant decrease in GFAP mRNA and protein levels in ALF patients compared to controls. While the loss of EAAT‐2 protein in ALF samples was post‐translational in nature, EAAT‐1 protein remained within normal limits. Immunohistochemistry confirmed that, in all cases, the losses of EAAT‐2 and GFAP were uniquely astrocytic in their localization. AQP‐4 mRNA expression was significantly increased and its immunohistochemistry demonstrated increased AQP‐4 immunoreactivity in the glial end‐feet process surrounding the microvessels. These findings provide evidence of selective alterations in the expression of genes coding for key astrocytic proteins implicated in central nervous system (CNS) excitability and brain edema in human ALF.
86.
Fructose-induced structural and functional modifications of hemoglobin: implication for oxidative stress in diabetes mellitus 总被引:1,自引:0,他引:1
Increased fructose concentration in diabetes mellitus causes fructation of several proteins. Here we have studied fructose-induced modifications of hemoglobin. We have demonstrated structural changes in fructose-modified hemoglobin (Fr-Hb) by enhanced fluorescence emission with excitation at 285 nm, more surface accessible tryptophan residues by using acrylamide, changes in secondary and tertiary structures by CD spectroscopy, and increased thermolability by using differential scanning calorimetry in comparison with those of normal hemoglobin, HbA(0). Release of iron from hemoglobin is directly related with the extent of fructation. H2O2-induced iron release from Fr-Hb is significantly higher than that from HbA(0). In the presence of H2O2, Fr-Hb degrades arachidonic acid, deoxyribose and plasmid DNA more efficiently than HbA(0), and these processes are significantly inhibited by desferrioxamine or mannitol. Thus increased iron release from Fr-Hb may cause enhanced formation of free radicals and oxidative stress in diabetes. Compared to HbA(0), Fr-Hb exhibits increased carbonyl formation, an index of oxidative modification. Functional modification in Fr-Hb has also been demonstrated by its decreased peroxidase activity and increased esterase activity in comparison with respective HbA(0) activities. Molecular modeling study reveals Lys 7alpha, Lys 127alpha and Lys 66beta to be the probable potential targets for fructation in HbA(0). 相似文献
87.
Thakur M Chaba R Mondal AK Chakraborti PK 《The Journal of biological chemistry》2008,283(12):8023-8033
Eukaryotic type Ser/Thr protein kinases have recently been shown to regulate a variety of cellular functions in bacteria. PknA, a transmembrane Ser/Thr protein kinase from Mycobacterium tuberculosis, when constitutively expressed in Escherichia coli resulted in cell elongation and therefore has been thought to be regulating morphological changes associated with cell division. Bioinformatic analysis revealed that PknA has N-terminal catalytic, juxtamembrane, transmembrane, and C-terminal extracellular domains, like known eukaryotic type Ser/Thr protein kinases from other bacteria. To identify the minimum region capable of exhibiting phosphorylation activity of PknA, we created several deletion mutants. Surprisingly, we found that the catalytic domain itself was not sufficient for exhibiting phosphorylation ability of PknA. However, the juxtamembrane region together with the kinase domain was necessary for the enzymatic activity and thus constitutes the catalytic core of PknA. Utilizing this core, we deduce that the autophosphorylation of PknA is an intermolecular event. Interestingly, the core itself was unable to restore the cell elongation phenotype as manifested by the full-length protein in E. coli; however, its co-expression along with the C-terminal region of PknA can associate them in trans to reconstitute a functional protein in vivo. Therefore, these findings argue that the transmembrane and extracellular domains of PknA, although dispensable for phosphorylation activities, are crucial in responding to signals. Thus, our results for the first time establish the significance of different domains in a bacterial eukaryotic type Ser/Thr kinase for reconstitution of its functionality. 相似文献
88.
Saxena R Kanudia P Datt M Dar HH Karthikeyan S Singh B Chakraborti PK 《The Journal of biological chemistry》2008,283(35):23754-23764
Genes encoding the peptide deformylase enzyme (def) are present in all eubacteria and are involved in the deformylation of the N-formyl group of newly synthesized polypeptides during protein synthesis. We compared the amino acid sequences of this enzyme in different mycobacterial species and found that they are highly conserved (76% homology with 62% identity); however, when this comparison was extended to other eubacterial homologs, it emerged that the mycobacterial proteins have an insertion region containing three consecutive arginine residues (residues 77-79 in Mycobacterium tuberculosis peptide deformylase (mPDF)). Here, we demonstrate that these three arginines are important for the activity of mPDF. Circular dichroism studies of wild-type mPDF and of mPDF containing individual conservative substitutions (R77K, R78K, or R79K) or combined substitutions incorporated into a triple mutant (R77K/R78K/R79K) indicate that such mutations cause mPDF to undergo structural alterations. Molecular modeling of mPDF suggests that the three arginines are distal to the active site. Molecular dynamics simulations of wild-type and mutant mPDF structures indicate that the arginines may be involved in the stabilization of substrate binding pocket residues for their proper interaction with peptide(s). Treatment with 5'-phosphothiorate-modified antisense oligodeoxyribonucleotides directed against different regions of def from M. tuberculosis inhibits growth of Mycobacterium smegmatis in culture. Taken together, these results hold out the possibility of future design of novel mycobacteria-specific PDF inhibitors. 相似文献
89.
Kunjupillai Vijayan Shyama Prasad Chakraborti Sezai Ercisli Partha Deb Ghosh 《Plant Growth Regulation》2008,56(1):61-69
Mulberry is an economically important tree, used for feeding the silkworm Bombyx mori L. Effect of different levels of NaCl on growth and development of mulberry has been studied using five mulberry genotypes
selected on the basis of their performance under in vitro salinity. The study while endorsing the efficacy of in vitro screening
of axillary buds of mulberry for salt tolerance, showed genotypic variability in its response to salinity. Salinity reduced
growth and development of all genotypes. However, the putative tolerant genotypes showed better performance than the putative
susceptible genotypes. Under low salinity (<0.5% NaCl) salt tolerant genotypes showed an increase in chlorophyll and protein
concentrations, while in susceptible genotypes both were reduced by 3–58% at 0.5% NaCl and 50–64% at 1.00% NaCl. Leaf thickness
increased by 16% at 1.00% NaCl in C776 and reduced by 1.0% in Mandalaya. The increase in chlorophyll concentration and leaf
thickness under high salinity can be considered as preliminary selection parameters for salt tolerance in mulberry. The study
confirmed the efficacy of in vitro method for screening of large number of genotypes for salt tolerance in mulberry. 相似文献
90.
Chakraborti D Sarkar A Mondal HA Schuermann D Hohn B Sarmah BK Das S 《Plant cell reports》2008,27(10):1623-1633
A binary expression vector was constructed containing the insecticidal gene Allium sativum leaf agglutinin (ASAL), and a selectable nptII marker gene cassette, flanked by lox sites. Similarly, another binary vector was developed with the chimeric cre gene construct. Transformed tobacco plants were generated with these two independent vectors. Each of the T(0) lox plants was crossed with T(0) Cre plants. PCR analyses followed by the sequencing of the target T-DNA part of the hybrid T(1) plants demonstrated the excision of the nptII gene in highly precised manner in certain percentage of the T(1) hybrid lines. The frequency of such marker gene excision was calculated to be 19.2% in the hybrids. Marker free plants were able to express ASAL efficiently and reduce the survivability of Myzus persiceae, the deadly pest of tobacco significantly, compared to the control tobacco plants. Results of PCR and Southern blot analyses of some of the T(2) plants detected the absence of cre as well as nptII genes. Thus, the crossing strategy involving Cre/lox system for the excision of marker genes appears to be very effective and easy to execute. Documentation of such marker excision phenomenon in the transgenic plants expressing the important insecticidal protein for the first time has a great significance from agricultural and biotechnological points of view. 相似文献