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排序方式: 共有418条查询结果,搜索用时 15 毫秒
1.
When tobacco leaf extracts are treated with phenol, ca 20% of the ribonuclease (RNase) activity survives and can be measured when the phenol is removed. After purification, the resistant RNase is inactivated by phenol; this suggests that tobacco leaves contain material that protects the RNase. Phenol-resistant RNase may be one of the TMV-RNA inactivating systems present in phenol extracts of tobacco leaves. 相似文献
2.
N. Hayashi M. Sholichin T. Sakao Y. Yamamura H. Komae 《Biochemical Systematics and Ecology》1980,8(2):109-113
A survey of chemical composition of 23 species of Asarum subgenus Heterotropa showed that the five groups could be distinguished on the basis of the presence or absence of asatone, phenol ethers and terpenes. 相似文献
3.
The concurrent bacterial degradation of 2-(2-methyl-4-chlorophenoxy)propionic acid and 2,4-dichlorophenoxyacetic acid was studied using a stirred tank reactor and a bacterial culture which had been originally derived by enrichment with MCPP. High pressure liquid chromatographic methodology was used to measure both herbicides and it also resolved the corresponding phenols as intermediates, i.e., 2-methyl-4-chlorophenol and 2,4-dichlorophenol. Gas chromatography-mass spectrometry was used to verify the intermediates. UV scans of spent cultures showed that the wave-length of maximum absorption shifted from 282 nm to 280 nm toward the end of incubation, but the characteristic peaks of maximum absorption of these compounds could not be used resolved because of the overlap. 相似文献
4.
《Free radical research》2013,47(11):1345-1358
AbstractThis study determines that cytochrome c (cyt c) catalyses the oxidation of phenol compounds (Phen) in the presence of H2O2 or linoleic acid hydroperoxide (LOOH), generating Phen-derived free radicals or other reactive metabolites. These products irreversibly inactivated the dihydrolipoamide dehydrogenase from Trypanosoma cruzi (T cruzi LADH), depending on: the Phen structure, peroxide type, activated cyt c, incubation time and presence of an antioxidant. Nordihydroguaiaretic acid (NDGA) and caffeic acid (CAFF) with cyt c/H2O2 or cyt c/LOOH were the most effective inhibitors of T cruzi LADH. The comparison of inactivation values for T cruzi and mammalian heart enzymes demonstrated a greater sensitivity of T cruzi LADH to Phen. GSH, N-acetylcysteine, NAD(P)H, ascorbate and trolox, prevented T cruzi LADH inactivation by acetaminophen. The role of the Phen as potential trypanocidal systems is discussed. 相似文献
5.
《Free radical research》2013,47(1):102-111
AbstractAstaxanthin when esterified with ferulic acid is better singlet oxygen quencher with k2 = (1.58 ± 0.1) 1010 L mol? 1s? 1 in ethanol at 25°C compared with astaxanthin with k2 = (1.12 ± 0.01) 109 L mol? 1s? 1. The ferulate moiety in the astaxanthin diester is a better radical scavenger than free ferulic acid as seen from the rate constant of scavenging of 1-hydroxyethyl radicals in ethanol at 25°C with a second-order rate constant of (1.68 ± 0.1) 108 L mol? 1s? 1 compared with (1.60 ± 0.03) 107 L mol? 1s? 1 for the astaxanthin:ferulic acid mixture, 1:2 equivalents. The mutual enhancement of antioxidant activity for the newly synthetized astaxanthin diferulate becoming a bifunctional antioxidant is rationalized according to a two-dimensional classification plot for electron donation and electron acceptance capability. 相似文献
6.
H E Knoell 《Biochemical and biophysical research communications》1979,91(3):919-925
A soluble enzyme complex (~ 2×106 daltons) was isolated from the cytoplasmic membrane of . It contains a high amount of 2-octaprenyl phenol, whereas ubiquinone-8, phospholipids and typical enzymes of the cytoplasmic membrane are largely excluded. Upon addition of a cytoplasmic enzyme and substrates, the pool of 2-octaprenyl phenol was quantitatively processed to ubiquinone-8. It is assumed that this complex represents the ubiquinone-8 synthesis apparatus supplied with the substrate 2-octaprenyl phenol. 相似文献
7.
8.
Marwa Youssef Einas H. El-Shatoury Sahar S. Ali Gamila E. El-Taweel 《Bioremediation Journal》2019,23(2):53-71
Biodegradation of phenol has been investigated using a bacterial consortium consisting of two bacterial isolates; one of them used for the first time in phenol biodegradation. This consortium was isolated from activated sludge and identified as Providencia stuartii PL4 and Pseudomonas aeruginosa PDM (accession numbers KY848366 and MF445102, respectively). The degradation of phenol by this consortium was optimal at pH 7 with using 1500?mg?l?1 ammonium chloride as a nitrogen source. Interestingly, after optimizing the biodegradation conditions, this consortium was able to degrade phenol completely up to 1500?mg?l?1 within 58?h. The immobilization of this consortium on various supporting materials indicated that polyvinyl alcohol (PVA)-alginate beads and polyurethane foam (PUF) were more suitable for biodegradation process. The freely suspended cells could degrade only 6% (150?mg?l?1) of 2500?mg?l?1 phenol, whereas, the immobilized PVA-alginate beads and the immobilized PUF degraded this concentration completely within 120?h of incubation with degradation rates (q) 0.4839 and 0.5368 (1/h) respectively. Thus, the immobilized consortium of P. stuartii PL4 and P. aeruginosa PDM can be considered very promising in the treatment of effluents containing phenol. 相似文献
9.
Xiaoyun Guo Zhenghong Li Xiaonan Wang Jing Wang Juan Chala Yinghua Lu Haoran Zhang 《Biotechnology and bioengineering》2019,116(12):3349-3359
Microbial biosynthesis has been extensively adapted for the production of commodity chemicals using renewable feedstocks. This study integrated metabolite biosensors into rationally designed microbial cocultures to achieve high-efficiency bioproduction of phenol from simple carbon substrate glucose. Specifically, two sets of E. coli–E. coli cocultures were first constructed for accommodation of two independent phenol biosynthesis pathways via 4-hydroxybenzoate (4HB) and tyrosine (TYR), respectively. Biosensor-assisted microbial cell selection mechanisms were subsequently incorporated into the coculture systems to address the insufficient pathway intermediate provision that limited the overall bioproduction. For the 4HB- and TYR-dependent pathways, this approach improved the phenol production by 2.3- and 3.9-fold, respectively, compared to the monoculture controls. Notably, the use of biosensor-assisted cell selection strategy in monocultures resulted in reduced phenol production, highlighting the advantage of coculture engineering for coupling with biosensing. After stepwise optimization, the phenol bioproduction yield of the engineered coculture's reached 0.057 g/g glucose. Furthermore, the coculture biosynthesis was successfully scaled up at both shake flask and bioreactor levels. Overall, the findings of this study demonstrate the outstanding potential of coupling biosensing and modular coculture engineering for advancing microbial biosynthesis of valuable molecules from renewable carbon substrates. 相似文献
10.
针对已报道属于羟基肟酸(丁布)、酚酸和酞酸酯类的稗草潜在的化感物质,本文以水稻、稗草和莴苣为试验材料,对2,4-二叔丁基酚、对羟基扁桃酸2种酚酸以及3种酞酸酯类物质的化感活性进行了研究.采用高效液相色谱法( HPLC)研究了上述5种物质以及丁布在稗草组织、根区土壤和种子萌发液的含量.结果表明:在100μg·ml-1作用浓度下,对羟基扁桃酸对莴苣、水稻以及稗草的种子萌发和幼苗生长的综合抑制活性最弱,2,4-二叔丁基酚化感抑制活性相对最强.酞酸二甲酯、酞酸二异辛酯和2,4-二叔丁基酚这3种物质对稗草的抑制活性大干水稻.通过HPLC只在稗草苗期叶、根和种子萌发液中检测出对羟基扁桃酸,其含量分别为9.72 μg·g-1、7.29 μg·g-1和0.24 μg·ml-1,而其他生长期组织以及根区土壤中均未检出.所有样品均未检测出2,4-二叔丁基酚、丁布和3种酞酸酯类物质.对羟基扁桃酸的浓度-效应试验显示,接近实测浓度(20 μg·g-1)时其对3种受试植物没有显著的化感抑制效应.本研究表明,对羟基扁桃酸不是稗草中主要的化感物质;通过HPLC-标准物质比对方法可以准确分析上述6种化合物,并证实了稗草不含有2,4-二叔丁基酚、丁布和酞酸酯类物质. 相似文献