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Surjeet Kour 《代数通讯》2013,41(11):4100-4110
It is shown that the derivation y r ? x + (xy s + g)? y , where 0 ≤ r < s are integers, is a simple derivation of k[x, y], the polynomial ring in two variables over a field k of characteristic zero. 相似文献
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Lokendra Kumar Balvinder Singh Dilip Kumar Adhikari Joydeep Mukherjee Debashish Ghosh 《Applied biochemistry and biotechnology》2012,166(7):1723-1735
Purification and characterization of halotolerant, thermostable alkaline l-glutaminase from a Bacillus sp. LKG-01 (MTCC 10401), isolated from Gangotri region of Uttarakhand Himalaya, is being reported in this paper. Enzyme has
been purified 49-fold from cell-free extract with 25% recovery (specific activity 584.2 U/mg protein) by (NH4)2SO4 precipitation followed by anion exchange chromatography and gel filtration. Enzyme has a molecular weight of 66 kDa. l-Glutaminase is most active at pH 11.0 and stable in the pH range 8.0–11.0. Temperature optimum is 70 °C and is completely
stable after 3 h pre-incubation at 50 °C. Enzyme reflects more enhanced activity with 1–20% (w/v) NaCl, which is further reduced to 80% when NaCl concentration was increased up to 25%. l-Glutaminase is almost active with K+, Zn2+, and Ni2+ ions and K
m and V
max values of 240 μM and 277.77 ± 1.1 U/mg proteins, respectively. Higher specific activity, purification fold, better halo-tolerance,
and thermostability would make this enzyme more attractive for food fermentation with respect to other soil microbe derived
l-glutaminase reported so far. 相似文献
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Deepika Geedkar Ashok Kumar Gagandeep Kour Reen Pratibha Sharma 《Journal of heterocyclic chemistry》2020,57(4):1963-1973
Present paper elicits the multicomponent reaction (MCR) strategy assisted by titania nanoparticles hosted on silica (TiO2.SiO2 NPs) as heterogeneous catalyst to synthesize a series of pharmacologically significant 2,3-diaryl-3,4-dihydroimidazo[4,5-b]indole derivatives. To the best of our information, the use of isatin as one of the precursors was hitherto unreported. The decrease in reaction time, low catalyst loading, high product yield (up to 92%), and excellent reusability of the catalyst (up to 7 cycles) put this protocol under the umbrella of green chemistry tenets. Characterization of catalysts was achieved through a number of techniques viz., energy-dispersive X-ray (EDX) spectroscopy, field emission scanning electron microscopy (FESEM), powder X-ray diffraction (XRD), fourier transform infrared (FTIR) spectra of adsorbed pyridine, temperature-programmed desorption of ammonia, and porosity measurements by nitrogen adsorption (Brunauer–Emmett–Teller [BET] method). Also, the structures of synthesized compounds were corroborated on the basis of FTIR, nuclear magnetic resonance (NMR), mass, and elemental analyses data. 相似文献
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Conformational structure of peptides containing dehydroalanine: Formation of β‐bend ribbon structure
Fateh S. Nandel Nandita Malik Balvinder Singh D. V. S. Jain 《International journal of quantum chemistry》1999,72(1):15-23
α,β‐Unsaturated amino acids (dehydroamino acids) have been found in naturally occurring antibiotics of microbial origin and in some proteins. Due to the presence of the CαCβ double bond, the dehydroamino acids influence the main‐chain and the side‐chain conformations. The lowest‐energy conformational state of the model tripeptides, Ac–X–ΔAla–NHMe, (X=Ala, Val, Leu, Abu, or Phe) corresponds to ϕ1=−30°, ψ1=120° and ϕ2=ψ2=30°. This structure is stabilized by the hydrogen bond between CO of the acetyl group and the NH of the amide group, resulting in the formation of a 10‐membered ring. In the model heptapeptide containing ΔAla at alternate position with Ala, Abu, and Leu, the lowest‐energy conformation corresponds to ϕ=−30° and ψ=120° for all the Ala, Abu, and Leu residues and ϕ=ψ=30° for all ΔAla residues. A graphical view of the molecule in this conformation reveals the formation of three hydrogen bonds involving the CO moiety of the ith residue and the NH moiety of the i+3th residue, resulting in a 10‐membered ring formation. In this structure, only alternate peptide bonds are involved in the intramolecular hydrogen‐bond formation unlike the helices and it has been named the β‐bend ribbon structure. The helical structures were predicted to be the most stable structures in the heptapeptide Ac–(Aib–ΔAla)3–NHMe with ϕ=±30°, ψ=±60° for Aib residues and ϕ=ψ=±30° for ΔAla residues. The computational results reveal that the ΔAla residue does not induce an inverse γ‐turn in the preceding residue. It is the competitive interaction of small solvent molecules with the hydrogen‐bonding sites of the peptide which gives rise to the formation of an inverse γ‐turn (ϕ1=−54°, ψ1=82°; ϕ2=44°, ψ2=3°) in the preceding residue to ΔAla. The computational studies for the positional preference of ΔAla in the peptide containing one ΔAla and nine Ala residues reveals the formation of a 310 helical structure in all the cases with the terminal preferences for ΔAla, consistent with the position of ΔAla in the natural antibiotics. The extended structures is found to be the most stable for poly‐ΔAla. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 72: 15–23, 1999 相似文献
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Shilpa Raina Vikas Sharma Zahid Nabi Sheikh Navneet Kour Shashank K. Singh Ali Zari Talal A. Zari Hesham F. Alharby Khalid Rehman Hakeem 《Molecules (Basel, Switzerland)》2022,27(7)
The current study was conducted to examine the in vitro anticancer potential of Cordia dichotoma (bark, leaves, pulp and seed). The plant material was collected from UT of J&K and methodical bioassays were carried out on ten human cancer cell lines (Michigan Cancer Foundation-7 (MCF-7), M.D. Anderson-Metastatic Breast (MDA-MB-231), Neuroblastoma-2a (N2A), SH-SY5Y, U-251, HCT-116, SW-620, A-549, MIA PaCa-2, Panc-1) from five different origins (breast, CNS, colon, lung, pancreas) respectively. Methanolic extracts were produced and fractions were then obtained from the extracts and evaluated for cytotoxicity. Mechanistic assays, HPLC, and GCMS profiling were performed on the highest active fraction. The Sulforhodamine B (SRB) assay determined the in vitro cytotoxicity. The findings revealed that the bark portion had in vitro cytotoxicity against the A-549 human lung cancer cell line. To our knowledge, this is the first study to show that the plant’s bark has anticancer properties and induced chromatin condensation, confirmed cell death via ROS generation, and significantly decreased colony formation in A-549 cell line from lung origin in a dose-dependent manner. Furthermore, HPLC and GCMS investigations indicated the presence of a number of bioactive molecules such as gallic acid (144,969.86) uV*sec, caffeic acid (104.26) uV*sec, ferulic acid (472.87) uV*sec, vanillic acid (13,775.39) uV*sec, palmitic acid (18.34%), cis vaccenic acid (28.81%), etc. and one of the compounds was reported for the first time from the bark. As a result of its promising efficacy, it may become an essential cancer chemopreventive or chemotherapeutic medication for patients with lung carcinoma. 相似文献
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Mandeep Kour Sandeep Kumar Savit Andotra Suman Lata Ramanpreet Kaur Gurpreet Singh 《Molecular physics》2020,118(13)
Dimethyl diphenyldithiophosphate complexes of titanium(IV), [(C5H5)2Ti{S2P(OAr)2}nCl2-n] (Ar?= 2,4-(CH3)C6H3, 2,5-(CH3)C6H3, 3,4-(CH3)C6H3, 3,5-(CH3)C6H3, 3-CH3-4-Cl-C6H3O; n?=?1 and 2) have been synthesised and characterised by various physicochemical techniques along with computational analysis of the complexes (2), (9) and (10) using density functional theory (DFT) and time-dependent DFT (TDDFT). Comparison of antimicrobial activity of the free ligands and complexes has shown that the complexes are more effective than the free ligands. The in vitro cytotoxic by using a MTT staining method with RAW 264.7 cells (mouse macrophages) have been investigated. On the basis of analytical and DFT data, a distorted trigonal bipyramidal around titanium(IV) may be assigned to the complexes (1–5) and distorted octahedral geometries for the complexes (6–10). 相似文献
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Surjeet Kour 《代数通讯》2013,41(9):4066-4083
If k is a field of characteristic zero, c ∈ k?{0}, s, t ≥ 1, and r ≥ 0 are integers, then it is shown that the k-derivation y r ? x + (y s x t + c)? y of the polynomial algebra k[x, y] is simple. 相似文献
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G L Kaul S K Badyal I K Daftari V K Gupta B Kour L K Mangotra Y Prakash N K Rao S K Sharma Gian Singh 《Pramana》1980,15(6):559-570
Experimental data on average shower particle multiplicity (〈N s〉) accumulated onp-nucleus interactions in the wide momentum region of 7.1–8000 GeV/c is investigated. It is observed that 〈N s〉 is represented exceedingly well as a function of (v vS). There are two physical processes which represent the experimental data reasonably well in the two momentum regionsviz 7.1–67.9 GeV/c and 67.9–8000 GeV/c. 〈N s〉=a( v S)/a+b fits the data in the low momentum region, whereas 〈N s〉=a +b ln (v vS) fits the experimental data in the high momentum region. The two physical processes are unified and represented by a single equation which is shown to be the consequence of two component theory and collective models. 相似文献