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101.
Nadia Shamim Sikander Ali Ikram-Ul-Haq 《Applied biochemistry and biotechnology》2013,169(8):2467-2477
In the present study, we report the optimisation of batch conditions for improved α-1,4-glucan-glucanohydrolase (GGH) secretion by a nitrous acid (NA)-treated Bacillus alcalophilus. The wild (isolate GCB-18) and NA-derivative (mutant GCBNA-4) were grown in a medium containing 10 g/L nutrient broth, 10 g/L starch, 5 g/L lactose, 2 g/L ammonium sulphate, 2 g/L CaCl2 and phosphate buffer (pH 7.6). Sodium dodecyl sulphate (SDS) was used as an enzyme inducer while batch fermentations were carried out at 40 °C. The mutant produced GGH in 40 h which was 15-fold higher than the wild in presence of SDS. Thermodynamic studies revealed that the mutant culture exhibited the capability for improved enzyme activity over a broad range of temperature (35–70 °C). The enzyme was purified by cation-exchange column chromatography with ~80 % recovery. The performance of fuzzy-logic system control was found to be highly promising for the improved substrate conversion rate. The correlation (1.045E?+?0025) among variables demonstrated the model terms as highly significant indicating commercial utility of the culture used (P?<?0.05). 相似文献
102.
Shamim Ahmad Kalim Javed I. G. Rathish Sameena Bano M. S. Alam 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):2516-2524
Treatment of the pyridazinone derivatives ( 1a, 1b ) with ethyl chloroformate afforded novel carbamates ( 2a, 2b ). Subsequent treatment of 2a, 2b with appropriate amines gave novel benzenesulfonylurea derivatives ( 3a–i ). All these compounds were characterized on the basis of 1 H NMR, IR, Mass spectral data and elemental analysis results. Preliminary biological testing of urea derivatives revealed that some compounds possess significant blood sugar lowering activity. Four compounds ( 3c, 3f, 3g , and 3h ) were found to have promising blood glucose lowering activity and may be used as lead compounds for developing new antidiabetic drugs. 相似文献
103.
Liaqat Ali Samina Ali Javid Hussain Ahmed Al‐Harrasi Abdul Latif Khan Syed Tasleem Hussain Shah Tania Shamim Rizvi 《Helvetica chimica acta》2014,97(4):556-560
The isolation and structure elucidation of a new triterpenic acid named floccosic acid ( 1 ) is reported on the basis of the 1D‐ and 2D‐NMR assignments. This secondary metabolite was isolated as a new constituent, along with the known triterpenoids, betulinic acid and β‐amyrin. All these compounds were purified by repeated column chromatography of the MeOH extract of Nepeta floccosa. The structure elucidation of the new compound was accomplished by the combined mass spectrometry (MS), infrared (IR) and ultraviolet (UV) absorption spectroscopy, one‐ (1H‐ and 13C‐) and two‐dimensional (H? C correlations; HMBC and HSQC) NMR techniques. The known compounds were identified by comparison of their physical and spectroscopic data with those reported in the literature. 相似文献
104.
Adsorption of globular protein, lysozyme, on thermosensitive poly(N-isopropylacrylamide) coated nanomagnetic particles was studied at different temperatures and pHs. It was observed that a maximum amount of lysozyme was adsorbed at a temperature above the lower critical solution temperature (LCST) (32 degrees C ) of the polymer and at the isoelectric point (pI=11) of lysozyme. Desorption was carried out using either NaH2PO4 (pH 4) or NaSCN (pH 6) as the desorbing agents. Conformational changes in lysozyme on desorption from nanomagnetic particles was studied by circular dichroism and intrinsic fluorescence spectroscopy. Lysozyme desorbed by NaH2PO4 showed very little conformational changes while lysozyme desorbed by NaSCN showed significant conformational changes, and 87% enzymatic activity was retained in the desorbed enzyme for desorption by NaH2PO4. 相似文献
105.
Heuristic techniques of optimization can be useful in designing complex experiments, such as microarray experiments. They have advantages over the traditional methods of optimization, particularly in situations where the search space is discrete. In this paper, a search procedure based on a genetic algorithm is proposed to find optimal (efficient) designs for both one- and multi-factor experiments. A genetic algorithm is a heuristic optimization method that exploits the biological evolution to obtain a solution of the problem. As an example, optimal designs for \(3\times 2\) factorial microarray experiments are presented for different numbers of arrays and for various sets of research questions. Comparisons between different operators of the genetic algorithm are performed by simulation studies. 相似文献
106.
The odd-parity ground state of the Λ baryon lies surprisingly low in mass. At 1405 MeV, it lies lower than the odd-parity ground-state nucleon, even though it has a valence strange quark. Using the PACS-CS (2+1)-flavor full-QCD ensembles, we employ a variational analysis using source and sink smearing to isolate this elusive state. For the first time we reproduce the correct level ordering with respect to nearby scattering thresholds. With a partially quenched strange quark to produce the appropriate kaon mass, we find a low-lying, odd-parity mass trend consistent with the experimental value. 相似文献