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1.
2.
Phosphoglucoisomerase from cytosol of immature wheat endosperm was purified 650-fold by ammonium sulphate fractionation, isopropyl
alcohol precipitation, DEAE-cellulose chromatography and gel filtration through Sepharose CL-6B. The enzyme, with a molecular
weight of about 130,000, exhibited maximum activity at pH 8.1. It showed typical hyperbolic kinetics with both fructose 6-P
and glucose 6-P withK
m of 0.18 mM and 0.44mM respectively. On either side of the optimum pH, the enzyme had lower affinity for the substrates. Using
glucose 6-P as the substrate, the equilibrium was reached at 27% fructose 6-P and 73% glucose 6-P with an equilibrium constant
of 2.7. The ΔF calculated from the apparent equilibrium constant was +597 cal mol-1. The activation energy calculated from the Arrhenius plot was 5500 cal mol-1. The enzyme was completely inhibited by ribose 5-P, ribulose 5-P and 6-phosphogluconate, withK
i values of 0.17, 0.25 and 0.14 mM respectively. The probable role of the enzyme in starch biosynthesis is discussed. 相似文献
3.
M. Mehta M. R. Saharan Randhir Singh 《Journal of plant biochemistry and biotechnology.》1995,4(1):11-16
Phosphoenolpyruvate (PEP) carboxylase (EC 4.1.1.31) was purified to apparent homogeneity with about 29% recovery from developing seeds of Brassica using ammonium sulfate fractionation, DEAE-cellulose chromatography, and gel filtration through Sepharose CL-6S. The purified enzyme with mol wt of about 400 kD exhibited maximum activity at pH 8.0. The enzyme had an absolute requirement for a divalent cation which was satisfied by Mg2+. The enzyme showed typical hyperbolic kinetics with PEP and HCO?3 with Km of 0.125 and 0.104 mM, respectively. Glu-6-P could activate the enzyme, whereas other phosphate esters such as fru-1, 6-P2, L-glycerophosphate and 3-PGA did not have any effect on the enzyme activity. Noneof the amino acids at 5 mM concentration had any significant effect on the enzyme activity. Nucleotide monophosphates and diphosphates did not inhibit the enzyme significantly, whereas ATP inhibited the enzyme activity. Oxaloacetate and malate inhibited the enzyme non-competitively with respect to PEP with Ki values of 0.127 and 1.25 mM, respectively. The enzyme activity in vivo seems to be regulated ’Tlainly by availability of its substrate and activation by glu-6-P, both of which are supplied through glycolysis. 相似文献
4.
5.
Two new constituents isolated from the roots of Toddalia asiatica and designated as toddanol and toddanone have been characterized as 5,7-dimethoxy-6-(2-hydroxy-3-methylbut-3-enyl)coumarin (1) and 5,7-dimethoxy-6-(3-methyl-2-oxobutanyl)coumarin (3), respectively, by spectral analysis and interconversion experiments. 相似文献
6.
Chemical investigation of the roots of G. mauritiana resulted in the isolation of two new alkaloids; 1-hydroxy-3-methoxy-2-(3-methylbut-2-enyl)-N-methylacridan-9-one (1) and 4,8-dimethoxy-3-(3-methylbut-2-enyl)-N-methyl-2-quinolone (6). The structures of these new bases have been established by chemical and spectroscopic methods and confirmed in the case of 6 by its synthesis. Interestingly, the formic acid-catalysed cyclisation of 1 gave the dealkylated product 3 along with the pyrano-[2, 3-a]-acridine (4). 相似文献
7.
Lord Wasim Reza Srinath Satyanarayna Donald A. Enarson Ajay M. V. Kumar Karuna Sagili Sujeet Kumar Levi Anand Prabhakar N. M. Devendrappa Ashish Pandey Nevin Wilson Sarabjit Chadha Badri Thapa Kuldeep Singh Sachdeva Mohan P. Kohli 《PloS one》2013,8(10)
Background
Light-emitting diode fluorescence microscopy (LED-FM) has been shown to be more sensitive than conventional bright field microscopy using Ziehl-Neelsen (ZN) stain in detecting sputum smear positive tuberculosis in controlled laboratory conditions. In 2012, Auramine O staining based LED-FM replaced conventional ZN microscopy in 200 designated microscopy centres (DMC) of medical colleges operating in collaboration with India’s Revised National Tuberculosis Control Programme. We aimed to assess the impact of introduction of LED-FM services on sputum smear positive case detection under program conditions.Methods
This was a before and after comparison study. In 15 randomly selected medical college DMCs, all presumptive TB patients who underwent sputum smear examination in the years 2011 (before LED-FM) and 2012 (after LED-FM) were compared. An additional 15 comparable DMCs that implemented conventional ZN sputum smear microscopy were also selected for comparison between 2011 and 2012.Results
The proportion of presumptive TB patients (PTP)found sputum smear positive increased by 30%- from 13.6% (3432/25159) in 2011 to 17.8% (4706/26426) in 2012 (P value <0.01) in the sites that implemented LED-FM microscopy, whereas in DMCs where the ZN staining procedure is followed the proportion of sputum smear positive had remained unchanged (13.0%versus 12.6%;P value0.31).Conclusion
Use of LED-FM significantly increased the proportion of smear positive cases among presumptive TB patients under routine program conditions in high workload laboratories. The study provides operational evidence needed to scale-up the use of LED-FM in similar settings in India and beyond. 相似文献8.
Shipeng Lu Karuna Chourey Marco Reiche Sandor Nietzsche Manesh B. Shah Thomas R. Neu Robert L. Hettich Kirsten Küsel 《Applied and environmental microbiology》2013,79(14):4272-4281
Microbial ferrous iron [Fe(II)] oxidation leads to the formation of iron-rich macroscopic aggregates (“iron snow”) at the redoxcline in a stratified lignite mine lake in east-central Germany. We aimed to identify the abundant Fe-oxidizing and Fe-reducing microorganisms likely to be involved in the formation and transformation of iron snow present in the redoxcline in two basins of the lake that differ in their pH values. Nucleic acid- and lipid-stained microbial cells of various morphologies detected by confocal laser scanning microscopy were homogeneously distributed in all iron snow samples. The dominant iron mineral appeared to be schwertmannite, with shorter needles in the northern than in the central basin samples. Total bacterial 16S rRNA gene copies ranged from 5.0 × 108 copies g (dry weight)−1 in the acidic central lake basin (pH 3.3) to 4.0 × 1010 copies g (dry weight)−1 in the less acidic (pH 5.9) northern basin. Total RNA-based quantitative PCR assigned up to 61% of metabolically active microbial communities to Fe-oxidizing- and Fe-reducing-related bacteria, indicating that iron metabolism was an important metabolic strategy. Molecular identification of abundant groups suggested that iron snow surfaces were formed by chemoautotrophic iron oxidizers, such as Acidimicrobium, Ferrovum, Acidithiobacillus, Thiobacillus, and Chlorobium, in the redoxcline and were rapidly colonized by heterotrophic iron reducers, such as Acidiphilium, Albidiferax-like, and Geobacter-like groups. Metaproteomics yielded 283 different proteins from northern basin iron snow samples, and protein identification provided a glimpse into some of their in situ metabolic processes, such as primary production (CO2 fixation), respiration, motility, and survival strategies. 相似文献
9.
Kim M Handley Nathan C VerBerkmoes Carl I Steefel Kenneth H Williams Itai Sharon Christopher S Miller Kyle R Frischkorn Karuna Chourey Brian C Thomas Manesh B Shah Philip E Long Robert L Hettich Jillian F Banfield 《The ISME journal》2013,7(4):800-816
Stimulation of subsurface microorganisms to induce reductive immobilization of metals is
a promising approach for bioremediation, yet the overall microbial community response is
typically poorly understood. Here we used proteogenomics to test the hypothesis that
excess input of acetate activates complex community functioning and syntrophic
interactions among autotrophs and heterotrophs. A flow-through sediment column was
incubated in a groundwater well of an acetate-amended aquifer and recovered during
microbial sulfate reduction. De novo reconstruction of community sequences
yielded near-complete genomes of Desulfobacter (Deltaproteobacteria),
Sulfurovum- and Sulfurimonas-like Epsilonproteobacteria and
Bacteroidetes. Partial genomes were obtained for Clostridiales
(Firmicutes) and Desulfuromonadales-like Deltaproteobacteria.
The majority of proteins identified by mass spectrometry corresponded to
Desulfobacter-like species, and demonstrate the role of this organism in
sulfate reduction (Dsr and APS), nitrogen fixation and acetate oxidation to CO2
during amendment. Results indicate less abundant Desulfuromonadales, and possibly
Bacteroidetes, also actively contributed to CO2 production via the
tricarboxylic acid (TCA) cycle. Proteomic data indicate that sulfide was partially
re-oxidized by Epsilonproteobacteria through nitrate-dependent sulfide oxidation
(using Nap, Nir, Nos, SQR and Sox), with CO2 fixed using the reverse TCA cycle.
We infer that high acetate concentrations, aimed at stimulating anaerobic heterotrophy,
led to the co-enrichment of, and carbon fixation in Epsilonproteobacteria.
Results give an insight into ecosystem behavior following addition of simple organic
carbon to the subsurface, and demonstrate a range of biological processes and community
interactions were stimulated. 相似文献
10.
Pandey Shiv S. Singh Sucheta Babu C. S. Vivek Shanker Karuna Srivastava N. K. Kalra Alok 《Planta》2016,243(5):1097-1114
Planta - Endophytes reside in different parts of the poppy plant and perform the tissue-specific functions. Most leaf endophytes modulate photosynthetic efficiency, plant growth, and productivity... 相似文献