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排序方式: 共有140条查询结果,搜索用时 156 毫秒
1.
2.
In Nostoc muscorum (Anabaena ATCC 27893) glutamate was not metabolised as a fixed nitrogen source, rather it functioned as an inhibitor of growth. The latter effect was nitrogen source specific and occurred in N2 -fixing cultures but not in cultures assimilating nitrate or ammonium. NO3 - -grown cultures lacked heterocysts and nitrogenase activity and showed a nearly 50% reduction in glutamate uptake rates, as well as in the final extent of glutamate taken up, compared to N2 -fixing or nitrogen-limited control cultures. NH4 + -grown cultures showed a similar response, except that the reduction in glutamate uptake rates and the final exten of glutamate taken up was over 80%. The present results suggest a relation between nitrate/ammounium nitrogen-dependent inhibition of glutamate uptake, probably via repression of the glutamate transport system, and glutamate toxicity. 相似文献
3.
The rate of synthesis and degradation of phospholipids in Mycobacterium smegmatis ATCC 607, grown at 27° C and 37° C was studied by incorporation of 32P into phospholipids and chase of radioactivity of the pulse-labelled phospholipids. A relatively low rate of synthesis and
degradation of phospholipids in cells growth at 27° C was observed as compared to those grown at 37° C. Phosphatidylethanolamine
(PE) had the maximum turnover at 37° C. However, at 27° C, cardiolipin (CL) showed a turnover rate higher than PE. Phosphatidylinositol
mannosides (PIMs) were metabolically more active at 37° C than at 27° C. The differences in metabolic activity of the phospholipids
at the two temperatures have been discussed. 相似文献
4.
Hyemin Choi Jae-Sam Hwang Ho Kim Dong Gun Lee 《Biochemical and biophysical research communications》2013
In our previous study, coprisin, a 43-mer defensin-like peptide, was derived from the dung beetle, Copris tripartitus, and a 9-mer CopA3 (monomer), truncated coprisin analog peptide, was designed. However, the antifungal effects of CopA3 are not known yet. In this study, the antifungal activity and mechanism of CopA3 were investigated and to develop a more effective antimicrobial peptide under physiological conditions, the enantiomeric d-CopA3 was designed. l- and d-CopA3 had a similar antifungal activity without chiral selectivity, and their activity was more potent than that of melittin used as a positive control. Furthermore, l- and d-CopA3 did not even show any hemolysis against human erythrocytes. Membrane studies using propidium iodide and bis-(1,3-dibutylbarbituric acid) trimethine oxonol [DiBAC4(3)], suggested that the antifungal effect of l- and d-CopA3 was due to the membrane-active mechanism, by contrast with coprisin possessing apoptotic mechanism without membrane permeabilization. Finally, the proteolytic resistance and antifungal activity of l- and d-CopA3 against trypsin was analyzed by HPLC and colony count assay. The results showed that only d-CopA3 maintained a potent antifungal activity despite the proteolytic condition. Therefore, this study suggests that d-CopA3 has potential as a novel antimicrobial agent. 相似文献
5.
《Biocatalysis and Biotransformation》2013,31(5-6):304-312
AbstractFlavobacterium ATCC 27551 was used as a model system for the preparation of magnetic biocatalysts. The magnetic modification was carried out by covalently binding carboxylate- and amino-modified magnetic nanoparticles onto cells. Magnetic Fe3O4 nanoparticles were also used for ionic adsorption on the cell surface. Magnetically modified cells were concentrated using a magnet and exhibited organophosphate hydrolyzing activity. The Taguchi method was used to optimize the binding of the magnetic nanoparticles on the cell surface. SEM image analyses demonstrated good linkage of the magnetic nanoparticles over the Flavobacterium ATCC 27551 cell surface. Under optimal conditions, the magnetic cells displayed specific activity ratios of 93%, 89% and 95%, compared with untreated cells, after the covalent coupling with carboxylate- and amino-modified magnetic nanoparticles and the ionic adsorption of magnetic Fe3O4 nanoparticles, respectively. 相似文献
6.
Atanas G. Atanasov Jian N. Wang Shi P. Gu Jing Bu Matthias P. Kramer Lisa Baumgartner Nanang Fakhrudin Angela Ladurner Clemens Malainer Anna Vuorinen Stefan M. Noha Stefan Schwaiger Judith M. Rollinger Daniela Schuster Hermann Stuppner Verena M. Dirsch Elke H. Heiss 《Biochimica et Biophysica Acta (BBA)/General Subjects》2013
Background
Peroxisome proliferator-activated receptor gamma (PPARγ) agonists are clinically used to counteract hyperglycemia. However, so far experienced unwanted side effects, such as weight gain, promote the search for new PPARγ activators.Methods
We used a combination of in silico, in vitro, cell-based and in vivo models to identify and validate natural products as promising leads for partial novel PPARγ agonists.Results
The natural product honokiol from the traditional Chinese herbal drug Magnolia bark was in silico predicted to bind into the PPARγ ligand binding pocket as dimer. Honokiol indeed directly bound to purified PPARγ ligand-binding domain (LBD) and acted as partial agonist in a PPARγ-mediated luciferase reporter assay. Honokiol was then directly compared to the clinically used full agonist pioglitazone with regard to stimulation of glucose uptake in adipocytes as well as adipogenic differentiation in 3T3-L1 pre-adipocytes and mouse embryonic fibroblasts. While honokiol stimulated basal glucose uptake to a similar extent as pioglitazone, it did not induce adipogenesis in contrast to pioglitazone. In diabetic KKAy mice oral application of honokiol prevented hyperglycemia and suppressed weight gain.Conclusion
We identified honokiol as a partial non-adipogenic PPARγ agonist in vitro which prevented hyperglycemia and weight gain in vivo.General significance
This observed activity profile suggests honokiol as promising new pharmaceutical lead or dietary supplement to combat metabolic disease, and provides a molecular explanation for the use of Magnolia in traditional medicine. 相似文献7.
8.
《Bioscience, biotechnology, and biochemistry》2013,77(11):1960-1961
FI-CMCase cDNA of Aspergillus aculeatus was expressed in Escherichia coli by using the tac promoter of E. coli. Transformants of E. coli harboring a plasmid pHEM06 containing mature form FI-CMCase cDNA produced FI-CMCase in the cytoplasm of the cells. The enzyme from E. coli cells was purified to yield 56% and it was immunological identical to that of FI-CMCase purified from A. aculeatus. 相似文献
9.
As an important biological methyl group donor, S-adenosyl-l-methionine is used as nutritional supplement or drug for various diseases, but bacterial strains that can efficiently produce S-adenosyl-l-methionine are not available. In this study, Corynebacterium glutamicum strain HW104 which can accumulate S-adenosyl-l-methionine was constructed from C. glutamicum ATCC13032 by deleting four genes thrB, metB, mcbR and Ncgl2640, and six genes metK, vgb, lysCm, homm, metX and metY were overexpressed in HW104 in different combinations, forming strains HW104/pJYW-4-metK-vgb, HW104/pJYW-4-SAM2C-vgb, HW104/pJYW-4-metK-vgb-metYX, and HW104/pJYW-4-metK-vgb-metYX-homm-lysCm. Fermentation experiments showed that HW104/pJYW-4-metK-vgb produced more S-adenosyl-l-methionine than other strains, and the yield achieved 196.7 mg/L (12.15 mg/g DCW) after 48 h. The results demonstrate the potential application of C. glutamicum for production of S-adenosyl-l-methionine without addition of l-methionine. 相似文献
10.
A new stemodinoside, stemodin-alpha-L-arabinofuranoside (5), was isolated from the plant Stemodia maritima. Incubation of stemodin (2) with Rhizopus oryzae ATCC 11145 gave 2 alpha,7 beta,13(S)-trihydroxystemodane (17) and 2 alpha,3 beta,13(S),16 alpha-tetrahydroxystemodane (18) whilst stemodinone (8) afforded 6 alpha,13(S)-dihydroxystemodan-2-one (19). The bioconversion of 2 beta,13(S)-dihydroxystemodane (10) by the fungus yielded 2 beta,7 beta,13(S)-trihydroxystemodane (20) whereas stemod-12-en-2-one (9) provided 7 beta,17-dihydroxystemod-12-en-2-one (21). The results provide useful information about the relationship between the functional groups of the substrates and their potential for bioconversion. 相似文献