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21.
Kailash C. Bhuyan Durga K. Bhuyan 《Biochimica et Biophysica Acta (BBA)/General Subjects》1977,497(3):641-651
Activities of catalase (H2O2 : H2O2 oxidoreductase, EC 1.11.1.6) and GSH peroxidase (GSH : H2O2 oxidoreductase, EC 1.11.1.9) have been measured in iris, ciliary body, retina, corneal epithelium, corneal endothelium, lens capsule-epithelium and decapsulated lens. 3-Amino-1H-1,2,4-triazole is a specific inhibitor of catalase and a potent cataractogenic agent. We observed marked inhibition of catalase activity in these tissues 1–6 h after the administration of a single intravenous dose of 1 g 3-aminotriazole per kg body weight in rabbit. This was associated with a 2–3-fold increase in the H2O2 concentrations of aqueous humor and vitreous humor. The increased peroxide concentrations were restored to the physiological levels as the catalase activity of eye tissues gradually returned to normal with time after injection. Under the conditions, GSH peroxidase activity of the afore-mentioned eye tissues was unaltered, GSH and protein sulfhydryl of lens were not changed, and ascorbic acid of aqueous humor and vitreous humor was not significantly altered. Based on these findings our conclusion is that catalase of eye tissues regulates the endogenous H2O2 in eye humors to the physiological level. We speculate that H2O2 may be the triggering factor in cataract induced by 3-aminotriazole. 相似文献
22.
Pinky Moni Bhuyan Sosanka Protim Sandilya Pranab Kumar Nath Sakshi Gandotra Sabtharishi Subramanian Devid Kardong Dip Kumar Gogoi 《Journal of Asia》2018,21(4):1171-1181
Mature larvae of Antheraea assamensis were collected from different locations of Assam to isolate the cellulolytic gut microflora. Altogether sixty cellulase degrading bacteria were isolated on agar plates containing microcrystalline cellulose as the sole carbon source. Among them, ten isolates showed hydrolyzing zone on agar plates containing carboxy methyl cellulose (CMC) after staining with Congo-red. Isolate MGB05 exhibited the highest CMCase activity (0.262?U/mL) at 72?h of incubation under submerged condition. FPase and β-glucosidase activity were 0.012?U/mL and 3.71?U/mL respectively. It showed maximum FPase (0.022?U/mL) activity on the 3rd day of incubation in the media containing wheat bran as a carbon source. β-glucosidase production was also found to be highest with wheat bran (20.03?U/mL) at 48?h of incubation. The optimum pH and temperature of FPase activity of MGB05 were found at 6.0 and 50?°C respectively while for β-glucosidase activity, it was maximum at pH?6.0 under 50?°C. In addition, metal ion Mg++ and Ca++ enhanced FPase activity up to 110.92% (0.026?U/mL) and 105.31% (0.025?U/mL) respectively. In-vitro antimicrobial bioassay of the most potent cellulolytic bacteria (MGB05) also showed high antimicrobial activity against Escherichia coli (2.9?cm) and Pseudomonas aeruginosa (3.0?cm). The isolate MGB05 has been identified based on 16S rDNA homology as Bacillus pumilus MGB05 with accession KP298708.2. Results encompass the prospective beneficial role of gut-microflora on digestion and disease resistance, which might be a potential probiotic component to enhance silk productivity. 相似文献
23.
Nitric oxide-induced salt stress tolerance in plants: ROS metabolism,signaling, and molecular interactions 总被引:2,自引:0,他引:2
Mirza Hasanuzzaman Hirosuke Oku Kamrun Nahar M. H. M. Borhannuddin Bhuyan Jubayer Al Mahmud Frantisek Baluska Masayuki Fujita 《Plant biotechnology reports》2018,12(2):77-92
Nitric oxide (NO), a non-charged, small, gaseous free-radical, is a signaling molecule in all plant cells. Several studies have proposed multifarious physiological roles for NO, from seed germination to plant maturation and senescence. Nitric oxide is thought to act as an antioxidant, quenching ROS during oxidative stress and reducing lipid peroxidation. NO also mediates photosynthesis and stomatal conductance and regulates programmed cell death, thus providing tolerance to abiotic stress. In mitochondria, NO participates in the electron transport pathway. Nitric oxide synthase and nitrate reductase are the key enzymes involved in NO-biosynthesis in aerobic plants, but non-enzymatic pathways have been reported as well. Nitric oxide can interact with a broad range of molecules, leading to the modification of protein activity, GSH biosynthesis, S-nitrosylation, peroxynitrite formation, proline accumulation, etc., to sustain stress tolerance. In addition to these interactions, NO interacts with fatty acids to form nitro-fatty acids as signals for antioxidant defense. Polyamines and NO interact positively to increase polyamine content and activity. A large number of genes are reprogrammed by NO; among these genes, proline metabolism genes are upregulated. Exogenous NO application is also shown to be involved in salinity tolerance and/or resistance via growth promotion, reversing oxidative damage and maintaining ion homeostasis. This review highlights NO-mediated salinity-stress tolerance in plants, including NO biosynthesis, regulation, and signaling. Nitric oxide-mediated ROS metabolism, antioxidant defense, and gene expression and the interactions of NO with other bioactive molecules are also discussed. We conclude the review with a discussion of unsolved issues and suggestions for future research. 相似文献
24.
This paper explores the possibility of classification based on Pareto multi-objective optimization. The efforts on solving optimization problems using the Pareto-based MOO methodology have gained increasing impetus on comparison of selected constraints. Moreover we have different types of classification problem based on optimization model like single objective optimization, MOO, Pareto optimization and convex optimization. All above techniques fail to generate distinguished class/subclass from existing class based on sensitive data. However, in this regard Pareto-based MOO approach is more powerful and effective in addressing various data mining tasks such as clustering, feature selection, classification, and knowledge extraction. The primary contribution of this paper is to solve such noble classification problem. Our work provides an overview of the existing research on MOO and contribution of Pareto based MOO focusing on classification. Particularly, the entire work deals with association of sub-features for noble classification. Moreover potentially interesting sub-features in MOO for classification are used to strengthen the concept of Pareto based MOO. Experiment has been carried out to validate the theory with different real world data sets which are more sensitive in nature. Finally, experimental results provide effectiveness of the proposed method using sensitive data. 相似文献
25.
26.
The kinetics of the slow folding and unfolding reactions of barstar, a bacterial ribonuclease inhibitor protein, have been studied at 23(+/-1) degrees C, pH 8, by the use of tryptophan fluorescence, far-UV circular dichroism (CD), near-UV CD, and transient mixing (1)H nuclear magnetic resonance (NMR) spectroscopic measurements in the 0-4 M range of guanidine hydrochloride (GdnHCl) concentration. The denaturant dependences of the rates of folding and unfolding processes, and of the initial and final values of optical signals associated with these kinetic processes, have been determined for each of the four probes of measurement. Values determined for rates as well as amplitudes are shown to be very much probe dependent. Significant differences in the intensities and rates of appearance and disappearance of several resolved resonances in the real-time one-dimensional NMR spectra have been noted. The NMR spectra also show increasing dispersion of chemical shifts during the slow phase of refolding. The denaturant dependences of rates display characteristic folding chevrons with distinct rollovers under strongly native as well as strongly unfolding conditions. Analyses of the data and comparison of the results obtained with different probes of measurement appear to indicate the accumulation of a myriad of intermediates on parallel folding and unfolding pathways, and suggest the existence of an ensemble of transition states. The energetic stabilities of the intermediates estimated from kinetic data suggest that they are approximately half as stable as the fully folded protein. The slowness of the folding and unfolding processes (tau = 10-333 s) and values of 20.5 (+/-1.4) and 18 (+/-0.5) kcal mol(-)(1) for the activation energies of the slow refolding and unfolding reactions suggest that proline isomerization is involved in these reactions, and that the intermediates accumulate and are therefore detectable because the slow proline isomerization reaction serves as a kinetic trap during folding. 相似文献
27.
Equilibrium amide hydrogen exchange studies of barstar have been carried out at pH 6.7, 32° SDC using one- and two-dimensional nuclear magnetic resonance. An unusually large fraction of the backbone amide hydrogens of barstar exchange too fast to be measured, and the exchange rates of only fifteen slow-exchanging amide sites including indole amides of two tryptophans could be measured in the presence of 0 to 1.8 M guanidine hydrochloride (GdnHCl). Measurement of exchange occurring in tens of seconds in the unfolding transition region was possible by the use of a fast stopped-flow mixing method. The observed exchange rates have been simulated in the EX2 limit according to a two-process model that incorporates two exchange-competent states: a transiently unfolded state (U*) in which many amide hydrogens are completely accessible to solvent-exchange, and a near-native locally unfolded state (N*), in which only one or a few amide hydrogens are completely accessible to solvent-exchange. The two-process model appears to account for the observed exchange behavior over the entire range of GdnHCl concentrations studied. For several measurable slow-exchanging amide hydrogens, the free energies of production of exchange-competent states from the exchange-incompetent native state are significantly higher than the free-energy of production of the equilibrium unfolded state from the native state, when the latter is determined from circular dichroism- or fluorescence-monitored equilibrium unfolding curves. The result implies that U*, which forms transiently in the strongly native-like conditions used for the hydrogen exchange studies, is higher in energy than the equilibrium-unfolded state. The higher energy of this transiently unfolded exchange-competent state can be attributed to either proline isomerization or to the presence of residual structure. On the basis of the free energies of production of exchange-competent states, the measured amide sites of barstar appear to define two structural subdomains—a three-helix unit and a two-β-strand unit in the core of the protein. Proteins 30:295–308, 1998. © 1998 Wiley-Liss, Inc. 相似文献
28.
Exploring the Least Studied Australian Eucalypt Genera: Corymbia and Angophora for Phytochemicals with Anticancer Activity against Pancreatic Malignancies 下载免费PDF全文
Deep Jyoti Bhuyan Quan V. Vuong Danielle R. Bond Anita C. Chalmers Ian A. van Altena Michael C. Bowyer Christopher J. Scarlett 《化学与生物多样性》2017,14(3)
While the pharmacological and toxicological properties of eucalypts are well known in indigenous Australian medicinal practice, investigations of the bioactivity of eucalypt extracts against high mortality diseases such as pancreatic cancer in Western medicine have to date been limited, particularly amongst the genera Corymbia and Angophora. Four Angophora and Corymbia species were evaluated for their phytochemical profile and efficacy against both primary and secondary pancreatic cancer cell lines. The aqueous leaf extract of Angophora hispida exhibited statistically higher total phenolic content (107.85 ± 1.46 mg of gallic acid equiv. per g) and total flavonoid content (57.96 ± 1.93 mg rutin equiv. per g) and antioxidant capacity compared to the other tested eucalypts (P < 0.05). Both A. hispida and A. floribunda aqueous extracts showed statistically similar saponin contents. Angophora floribunda extract exerted significantly greater cell growth inhibition of 77.91 ± 4.93% followed by A. hispida with 62.04 ± 7.47% (P < 0.05) at 100 μg/ml in MIA PaCa‐2 cells with IC50 values of 75.58 and 87.28 μg/ml, respectively. More studies are required to isolate and identify the bioactive compounds from these two Angophora species and to determine their mode of action against pancreatic malignancies. 相似文献
29.
Prasanta K. Bordoloi Purnajyoti D. Bhuyan Paran Boruah Manobjyoti Bordoloi Paruchuri G. Rao 《Phytochemistry letters》2009,2(1):22-24
As part of our ongoing programme for isolation of bioactive molecules from the flora of the Indo-Burma biodiversity belt, an unusual long chain alkylated α-methylene-γ-butyrolactone was isolated from the juice of ripe fruit of Artabotrys odoratissimus R.Br. Its structure was determined as 3-methylene-4-pentadecyldihydrofuran-2-one by spectroscopic methods. It was found to have good antifungal activity against Alternaria tenuissima Kunze Ex Pers. isolated from solasodine producing plant Solanum khasianum Clarke. Minimum Inhibitory Concentration (MIC) and IC50 for 3-methylene-4-pentadecyldihydrofuran-2-one were found as 300 and 51.37 μg/ml, respectively. The standard captan was found to have an MIC and IC50 of 200 and 35.52 μg/ml, respectively. 相似文献
30.
Salah Uddin Khan Henrik Salje A. Hannan Md. Atiqul Islam A. A. Mamun Bhuyan Md. Ariful Islam M. Ziaur Rahman Nazmun Nahar M. Jahangir Hossain Stephen P. Luby Emily S. Gurley 《PLoS neglected tropical diseases》2014,8(9)