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排序方式: 共有73条查询结果,搜索用时 15 毫秒
1.
Chelliah Edward Raja Kolandaswamy Anbazhagan Govindan Sadasivam Selvam 《World journal of microbiology & biotechnology》2006,22(6):577-585
Summary The use of microorganisms to remove heavy metals from industrial effluent is an area of extensive research and development.
Attempts have been made to isolate and characterize metal-resistant microorganisms from treated oil mill industry effluent
wastewater samples. The metal-resistant organisms that showed values of minimum inhibitory concentration towards metals (Cd,
Cr, Ni and Pb) ranging from 100 to 800 ppm level were screened. A potent metal-resistant organism, isolate BC15 from the wastewater
samples was tentatively identified as Pseudomonas sp. Detailed analysis of morphological, biochemical and 16S rDNA sequence of the isolate revealed that it is closely related
to Pseudomonas aeruginosa (94%). Pseudomonas BC15 was capable of absorbing 93% Ni, 65% Pb, 50% Cd and 30% Cr within 48 h from the medium containing 100 mg of each heavy
metal per liter. The multiple metal tolerance of this strain was also associated with resistance to antibiotics such as ampicillin,
tetracycline, chloramphenicol, erythromycin, kanamycin and streptomycin. 相似文献
2.
Hyoscyamine 6β-hydroxylase (H6H; EC 1.14.11.11), an important enzyme in the biosynthesis of tropane alkaloids, catalyzes the hydroxylation of hyoscyamine to give 6β-hydroxyhyoscyamine and its epoxidation in the biosynthetic pathway leading to scopolamine. Datura metel produces scopolamine as the predominant tropane alkaloid. The cDNA encoding H6H from D. metel (DmH6H) was cloned, heterologously expressed and biochemically characterized. The purified recombinant His-tagged H6H from D. metel (DmrH6H) was capable of converting hyoscyamine to scopolamine. The functionally expressed DmrH6H was confirmed by HPLC and ESI-MS verification of the products, 6β-hydroxyhyoscyamine and its derivative, scopolamine; the DmrH6H epoxidase activity was low compared to the hydroxylase activity. The Km values for both the substrates, hyoscyamine and 2-oxoglutarate, were 50 μM each. The CD (circular dichroism) spectrum of the DmrH6H indicated a preponderance of α-helicity in the secondary structure. From the fluorescence studies, Stern–Volmer constants for hyoscyamine and 2-oxoglutarate were found to be 0.14 M?1 and 0.56 M?1, respectively. These data suggested that the binding of the substrates, hyoscyamine and 2-oxoglutarate, to the enzyme induced significant conformational changes. 相似文献
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5.
Background
AMP-activated protein kinase (AMPK) is a fuel-sensing enzyme that is activated when cells experience energy deficiency and conversely suppressed in surfeit of energy supply. AMPK activation improves insulin sensitivity via multiple mechanisms, among which AMPK suppresses mTOR/S6K-mediated negative feedback regulation of insulin signaling.Results
In the present study we further investigated the mechanism of AMPK-regulated insulin signaling. Our results showed that 5-aminoimidazole-4-carboxamide-1 ribonucleoside (AICAR) greatly enhanced the ability of insulin to stimulate the insulin receptor substrate-1 (IRS1)-associated PI3K activity in differentiated 3T3-F442a adipocytes, leading to increased Akt phosphorylation at S473, whereas insulin-stimulated activation of mTOR was diminished. In 3T3-F442a preadipocytes, these effects were attenuated by expression of a dominant negative mutant of AMPK α1 subunit. The enhancing effect of ACIAR on Akt phosphorylation was also observed when the cells were treated with EGF, suggesting that it is regulated at a step beyond IR/IRS1. Indeed, when the cells were chronically treated with AICAR in the absence of insulin, Akt phosphorylation was progressively increased. This event was associated with an increase in levels of phosphatidylinositol -3,4,5-trisphosphate (PIP3) and blocked by Wortmannin. We then expressed the dominant negative mutant of PTEN (C124S) and found that the inhibition of endogenous PTEN per se did not affect phosphorylation of Akt at basal levels or upon treatment with AICAR or insulin. Thus, this result suggests that AMPK activation of Akt is not mediated by regulating phosphatase and tensin homologue (PTEN).Conclusion
Our present study demonstrates that AMPK exerts dual effects on the PI3K pathway, stimulating PI3K/Akt and inhibiting mTOR/S6K. 相似文献6.
7.
Chelliah MV Chackalamannil S Xia Y Eagen K Greenlee WJ Ahn HS Agans-Fantuzzi J Boykow G Hsieh Y Bryant M Chan TM Chintala M 《Bioorganic & medicinal chemistry letters》2012,22(7):2544-2549
Discovery of a novel nor-seco himbacine analog as potent thrombin receptor (PAR-1) antagonist is described. Despite low plasma level, these new analogs showed excellent ex vivo efficacy in the monkey platelet aggregation assay. A potent hydroxy metabolite generated in vivo was identified as the agent responsible for the ex vivo efficacy. Following this discovery, the metabolite series was optimized to obtain analogs that showed very good ex vivo efficacy along with excellent pharmacokinetic profile in c. monkey. 相似文献
8.
Suspension cultures of Catharanthus roseus were used to evaluate ultraviolet-B (UV-B) treatment as an abiotic elicitor of secondary metabolites. A dispersed cell suspension culture from C. roseus leaves in late exponential phase and stationary phase were irradiated with UV-B for 5 min. The stationary phase cultures were more responsive to UV-B irradiation than late exponential phase cultures. Catharanthine and vindoline increased 3-fold and 12-fold, respectively, on treatment with a 5-min UV-B irradiation. 相似文献
9.
NMR structures of the selenoproteins Sep15 and SelM reveal redox activity of a new thioredoxin-like family 总被引:5,自引:0,他引:5
Ferguson AD Labunskyy VM Fomenko DE Araç D Chelliah Y Amezcua CA Rizo J Gladyshev VN Deisenhofer J 《The Journal of biological chemistry》2006,281(6):3536-3543
Selenium has significant health benefits, including potent cancer prevention activity and roles in immune function and the male reproductive system. Selenium-containing proteins, which incorporate this essential micronutrient as selenocysteine, are proposed to mediate the positive effects of dietary selenium. Presented here are the solution NMR structures of the selenoprotein SelM and an ortholog of the selenoprotein Sep15. These data reveal that Sep15 and SelM are structural homologs that establish a new thioredoxin-like protein family. The location of the active-site redox motifs within the fold together with the observed localized conformational changes after thiol-disulfide exchange and measured redox potential indicate that they have redox activity. In mammals, Sep15 expression is regulated by dietary selenium, and either decreased or increased expression of this selenoprotein alters redox homeostasis. A physiological role for Sep15 and SelM as thiol-disulfide oxidoreductases and their contribution to the quality control pathways of the endoplasmic reticulum are discussed. 相似文献
10.
Calcium-dependent protein kinases (CDPKs) constitute a unique family of enzymes in plants that are characterized by a C-terminal calmodulin (CaM)-like domain. Through protein kinase assays, we have examined the levels of cucumber calcium-dependent kinase (CsCDPK) activity in various organs of cucumber seedlings and plants. The activity of CsCDPK was highest in cucumber plant leaves followed by seedling roots and hypocotyls; however, cucumber plant flowers, seedling cotyledons, and hooks had levels that were barely detectable. The CsCDPKs were immunolocalized using polyclonal antibodies that are highly specific against a part of the kinase domain of a calcium-dependent protein kinase (CsCDPKS) in the phloem sieve elements (SEs) in various organs of cucumber. In addition, this study indicates the presence of CsCDPKs in organelle-like bodies associated with the plasma membrane of sieve elements in mature stems and roots as well as in the storage bodies of immature seeds. These findings are discussed in terms of the likely roles played by CDPKs in the signal transduction pathways for Ca2+-regulated phloem transport of assimilates from leaves to various organs during growth and development of cucumber seedlings and plants. 相似文献