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81.
Preferential adsorption of water in the vapor phase by lignocellulosic residues for the production of anhydrous ethanol has been reported in this work. Rice straw, microcrystalline cellulose powder (MCCP) and bagasse were the lignocellulosic residues used as adsorbents. Starting with an ethanol concentration of 80–90% a final concentration above the azeotropic concentration was obtained. An energy analysis of the process was made and a possible explanation of phenomena suggested. 相似文献
82.
Anthony John Pastore Alvaro Montoya Manasi Kamat Kari B. Basso James S. Italia Abhishek Chatterjee Maria Drosou Dimitrios A. Pantazis Alexander Angerhofer 《Protein science : a publication of the Protein Society》2023,32(1):e4537
Oxalate decarboxylase from Bacillus subtilis is a binuclear Mn-dependent acid stress response enzyme that converts the mono-anion of oxalic acid into formate and carbon dioxide in a redox neutral unimolecular disproportionation reaction. A π-stacked tryptophan dimer, W96 and W274, at the interface between two monomer subunits facilitates long-range electron transfer between the two Mn ions and plays an important role in the catalytic mechanism. Substitution of W96 with the unnatural amino acid 5-hydroxytryptophan leads to a persistent EPR signal which can be traced back to the neutral radical of 5-hydroxytryptophan with its hydroxyl proton removed. 5-Hydroxytryptophan acts as a hole sink preventing the formation of Mn(III) at the N-terminal active site and strongly suppresses enzymatic activity. The lower boundary of the standard reduction potential for the active site Mn(II)/Mn(III) couple can therefore be estimated as 740 mV against the normal hydrogen electrode at pH 4, the pH of maximum catalytic efficiency. Our results support the catalytic importance of long-range electron transfer in oxalate decarboxylase while at the same time highlighting the utility of unnatural amino acid incorporation and specifically the use of 5-hydroxytryptophan as an energetic sink for hole hopping to probe electron transfer in redox proteins. 相似文献
83.
S. Ghosh P.C. Sadhukhan J. Chaudhuri D.K. Ghosh A. Mandal 《Journal of applied microbiology》1996,81(1):104-108
Highly toxic mercury compounds may come into the environment through the use of mercury compounds as disinfectants for hospital and household purposes, Hg catalyst in industries, burning of coal and petroleum products, mercury-based pesticides and fungicides used in agriculture, and seed dressings. Toxic effects of mercury can be counteracted by microbial cells through the enzymes mercuric reductase and organomercurial lyase. Immobilized mercury-resistant bacterial cells of Azotobacter chroococcum could effectively volatilize mercury from mercury-containing buffer and detoxify mercury compounds. Moreover, the efficiency of mercury volatilization was much greater than with the native cells, as immobilized cells can be reused. Immobilized cells continuously volatilized mercury from mercury-containing buffer after four consecutive 24 h cycles. The storage stability of immobilized cells was much better than that of the native cells. 相似文献
84.
A non-equilibrium thermodynamic theory of generalized Lotka-Volterra ecosystem has been presented. The main results consist of the derivation of a generalized expression of entropy-production for the evolutionary ecosystem and the study of its role in the analysis of ecological stability, succession and also in the formulation of some extremum principles characterising the evolution of the ecosystem. 相似文献
85.
The vaccinia virus D5 protein, which is required for DNA replication, is a nucleic acid-independent nucleoside triphosphatase. 总被引:4,自引:4,他引:0 下载免费PDF全文
The vaccinia virus D5 gene encodes a 90-kDa protein that is transiently expressed at early times after infection. Temperature-sensitive mutants with lesions in the D5 gene exhibit a fast-stop DNA- phenotype and are also impaired in homologous recombination. Here we report the overexpression of the D5 protein within the context of a vaccinia virus infection and its purification to apparent homogeneity. The purified protein has an intrinsic nucleoside triphosphatase activity which is independent of, and not stimulated by, any common nucleic acid cofactors. All eight common ribo- and deoxyribonucleoside triphosphates are hydrolyzed to the diphosphate form in the presence of a divalent cation. Implications for the role of D5 in viral DNA replication are addressed. 相似文献
86.
Sujoy Ghosh John W. Kyle Sara Dastgheib Francois Daussin Zhixiong Li Subhash Basu 《Glycoconjugate journal》1995,12(6):838-847
A 1-3 galactosyltransferase (GalT-3; UDP-Gal; GM2 1-3galactosyltransferase) was purified over 5100-fold from 19-day-old embryonic chicken brain homogenate employing detergent solubilization, -lactalbumin Sepharose, Q-Sepharose, UDP-hexanolamine Sepharose, and GalNAc1-4Gal-Synsorb column chromatography. The purified enzyme was resolved into two bands on reducing gels with apparent molecular weights of 62 kDa and 65 kDa, respectively. GalT-3 activity was also localized in the same regions by activity gel analysis and sucrose-density gradient centrifugation of a detergent-solubilized extract of 19-day-old embryonic chicken brain. Purified GalT-3 exhibited apparentK
mS of 33 µm, 22 µm and 14.4mM with respect to the substrates GM2, UDP-galactose, and MnCl2, respectively. Substrate specificity studies with the purified enzyme and a variety of glycosphingolipids, glycoproteins, and synthetic substrates revealed that the enzyme was highly specific only for the glycosphingolipid acceptors, GM2 and GgOse3Cer (asialo-GM2). Ovine-asialo-agalacto submaxillary mucin inhibited the transfer of galactose to GM2 but did not act as an acceptor in the range of concentrations tested. Polyclonal antibodies raised against purified GalT-3 inhibited GalT-3 activityin vitro and Western-immunoblot analysis of purified GalT-3 showed immunopositive bands at 62 and 65 kDa.Abbreviations CNS
central nervous system
- GM1
monosialotetraosylganglioside, Gal1-3GalNAc1-4(NeuAc2-3)Gal1-4Glc1-1Cer
- GM2
monosialotriaosylganglioside, GalNAc1-4(NeuAc2-3)Gal1-4Glc1-1Cer
- DSS
detergent solubilized supernatant
- ECB
embryonic chicken brain
- TBS
Tris-buffered saline 相似文献
87.
A complimentary DNA clone encoding the entire human palmitoyl-CoA ligase has been isolated from a liver cDNA library and sequenced in it's entirety. The predicted product is a 699 amino acid protein. Southern analysis utilizing the human palmitoyl-CoA ligase gene as a probe revealed varying degrees of similarity amongst various mammalian species. The palmitoyl-CoA ligase gene is highly expressed in liver, heart, skeletal muscle and kidney, and to a lesser extent in brain, lung, placenta and pancreas. The expression of palmitoyl-CoA ligase in various tissue parallels the function of this enzyme in the metabolism of fatty acids in these tissues. 相似文献
88.
89.
90.
Comparison of aldolase isozymes in placenta, HeLa cells, and human fibroblast cultures 总被引:1,自引:0,他引:1
The aldolase specific activity of the human carcinoma cell line, HeLa, against fructose 1,6-diphosphate as substrate is 4- to 5-fold greater than the specific activity of diploid human fibroblast cultures derived from skin and lung. HeLa aldolase is isozyme is predominantly the A type and its substrate preferences resemble human placenta. These findings provide further support for the oncofetal enzyme consitution of HeLa cells. 相似文献