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Genetic control of hydrolytic enzymes in germinated barley (Hordeum vulgare L.) / by Cheng-dao Li.Li, Cheng-Dao January 1997 (has links)
Bibliography: leaves 114-141. / vi, 141, [42] leaves, [19] leaves of plates : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Using RFLP, STS-PCR and isoenzyme techniques, maps the structural genes of hydrolytic enzymes important in seed germination processes, and determines the contribution of each gene to the activity of the enzyme. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Science, 1998
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Inhibition de la S-adénosyl-L-homocystéine hydrolase Synthèses et études du mode d'action de nouveaux inhibiteurs irréversibles; modélisation et synthèses de nouveaux acyclonucléosides dirigés contre le site actif de l'enzyme /Glapski, Cédric Guillerm, Georges January 2005 (has links) (PDF)
Reproduction de : Thèse doctorat : Chimie bioorganique : Reims : 2004. / Titre provenant de l'écran titre. Bibliogr. : 129 réf.
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Pretreatment and enzymatic hydrolysis of lignocellulosic materialsCheng, Wei, January 2001 (has links)
Thesis (M.S.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains xii, 173 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 138-142).
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Part I, Cobalt thiolate complexes modeling the active site of cobalt nitrile hydratase ; Part II, Formation of inorganic nanoparticles on protein scaffolding in Esherichia coli glutamine synthetase /Kung, Irene Yuk Man, January 2002 (has links)
Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 180-187).
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Optimization of biocatalysis of chlorophyllase in neat organic solvent mediaArriagada Strodthoff, Paula January 2004 (has links)
The biocatalysis of a crude chlorophyllase extract, obtained from the biomass culture of Phaeodactylum tricornutum, in neat organic solvent media was investigated. The addition of selected excipients, including crown ether (enzyme:crown ether, 135:1--2.7:1, w/w), dextran (enzyme:dextran, 1:2--1:0.25, w/w), Span 40 and Span 60 (enzyme:Span, 1:2, w/w) and sodium bis (2-ethylhexyl) sulfosuccinate (enzyme:AOT, 1:12.6, w/w), to the crude solid enzyme preparation decreased the chlorophyllase activity. The effects of selected parameters, including solvent hydrophobicity (Log P, 2.40--4.45), initial water activity (aw, 0.44--0.97), agitation speed (0--200 rpm), reaction temperature (25--45°C) and enzyme concentration (1.67--5.3 mg solid enzyme/mL) on chlorophyllase activity, were investigated using a crude solid enzyme. The experimental findings showed that the highest chlorophyllase specific activity of 362.4 nmol hydrolyzed chlorophyll/g solid enzyme/min and bioconversion yield of 90.7% were obtained with the hexane/octanone mixture (98.7:1.3, v/v), aw of 0.90, agitation speed of 200 rpm, reaction temperature of 35°C and enzyme concentration of 3.33 mg solid enzyme/mL.
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Characterization of 1, 2-DCA degrading Ancylobacter aquaticus strains isolated in South Africa.Pillay, Thiloshini. January 2011 (has links)
1,2-Dichloroethane (1,2-DCA), a highly toxic and recalcitrant compound, is produced
anthropogenically in larger quantities than any other chlorinated compound. It is regarded
as a mutagen and carcinogen, thus making it a priority target molecule for biological
degradation. In addition, the intermediates of 1,2-DCA degradation are highly reactive
and toxic, due to the electrophilic nature of the carbonyl groups in these compounds.
Aerobic biodegradation of 1,2-DCA, resulting in complete mineralization, has previously
been reported in Xanthobacter autotrophicus GJ10 and some Ancylobacter aquaticus
strains. X. autotrophicus GJ10 has been found to possess chloroacetaldehyde (CAA)
dehydrogenase and haloacid (HA) dehalogenase enzymes, both of which play a crucial
role in 1,2-DCA degradation. Five strains of Ancylobacter aquaticus capable of utilizing
1,2-DCA as a sole carbon and energy source have recently been isolated in our
laboratory. The degradation potential and specific dehalogenase activities of these
bacterial isolates against 1,2-DCA and other halogenated compounds as a carbon source
were investigated and compared to previously characterized organisms, viz., X.
autotrophicus GJ10 and Ancylobacter aquaticus strains AD25 and AD27. Furthermore,
this study proposed to detect the presence of the CAA dehydrogenase (aldB) and HA
dehalogenase (dhlB) encoding genes in these isolates. Growth of all strains in the
presence of 1,2-DCA as a carbon source was monitored over an 84 h period, in minimal
medium supplemented with either vitamins or yeast extract. Dehalogenase activities were
measured colorimetrically by monitoring halide release by crude cell extracts of the
isolates. In order to detect the presence of dhlB and aldB genes, genomic DNA of the
isolates was digested with individual restriction endonucleases, viz., EcoRI, PstI, HindIII
and BamHI, and then subjected to Southern hybridization experiments. All isolates
demonstrated significant growth rates in both vitamin and yeast extract supplemented
media, with the former having a greater overall growth effect. Ancylobacter aquaticus
DH5 demonstrated the highest growth rate of 0.147.h-1 in the presence of vitamins while
Ancylobacter aquaticus DH12 displayed the highest growth rate of 0.118.h-1 with yeast
extract. Optimum haloalkane dehalogenase activities of these bacterial isolates were confirmed at pH 8, similar to the activity in X. autotrophicus GJ10, while haloaciddehalogenase activity had a broader pH range. Hydrolytic dehalogenase activity of the bacterial isolates using a range of halogenated aliphatic compounds was also determined.
Results demonstrated a wide substrate range with activity being observed on 1,3-
dibromopropane, 1,2-dibromoethane and 1,3-dichoropropene, for all isolates. Southern
Hybridization experiments confirmed the presence of both aldB and dhlB genes in X.
autotrophicus GJ10. The dhlB probe produced a positive signal for an EcoRI fragment in
Ancylobacter aquaticus DH12 while the aldB probe hybridized and produced a single
positive signal on similar sized PstI fragments for all organisms except A. aquaticus
AD25 which produced two positive signals. The results in this study demonstrate the
potential application of the newly isolated strains of Ancylobacter aquaticus. in future
bioremediation strategies. The detection of the genes involved in 1,2-DCA degradation
further support the use of these isolates and/or their enzymes for the degradation of 1,2-
DCA as well as other halogenated compounds. Future work need to determine sequence
similarity of these genes detected in A. aquaticus strains to the genes in Xanthobacter
autotrophicus GJ10 and other previously reported genes. It may also be important to
investigate the activity of the enzymes under various environmental conditions and to
determine enzyme structure and the catalytic sites, so as to gain knowledge of their
degradation potential on site. Characterization of enzymes at both the molecular and
protein levels may be necessary and beneficial for implementation in strategies involving
bioremediation for the biological degradation of a wide range of halogenated aliphatic
hydrocarbons. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2011.
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Biocatalysis of chlorophyllase in ternary micellar system using chlorophyll derivatives as substratesSamaha, Hiba. January 1996 (has links)
A partially purified chlorophyllase, obtained from alga Phaeodactylum tricornutum, was assayed for its hydrolytic activity towards the pheophytin in ternary micellar systems of hexane/Tris-HCl/surfactant. A wide range of surfactants, sorbitans (Span 20, 40, 60, 80 and 85) and polysorbates (Tween 20, 40, 60, 80 and 85), was used. The use of either 50 $ mu$M of Span 85 or 1 $ mu$M of Tween 80 increased the hydrolytic activity of chlorophyllase by 110 and 23%, respectively. The optimum values of pH, enzyme content, incubation time and temperature for the hydrolytic activity of chlorophyllase were determined as 8.25, 8 $ mu$g protein/ml, 60 min and 27.5$ sp circ$C, respectively. The enzyme was assayed for its hydrolytic activity in the most appropriate ternary system containing Span 85 with purified pheophytin, as well as chlorophyll derivatives, as substrates. Moreover, the values of $V sb{ rm max}/K sb{ rm m}$ ratio for chlorophyllase, using the partially purified pheophytin as substrate, in ternary systems with Span 85 and Tween 80 as surfactants, were 0.15 and 0.08, respectively; however, the value of $V sb{ rm max}/K sb{ rm m}$ ratio for the enzyme, in the ternary system with Span 85, using purified pheophytin as substrate was 0.07. The addition of optimized amounts of individual membrane lipids, L-$ alpha$-phosphatidylcholine, L-$ alpha$-phosphatidyl-DL-glycerol and $ beta$-carotene increased the hydrolytic activity of chlorophyllase, using partially purified pheophytin as substrate, by 50, 36 and 10%, respectively, for Span 85, and 30, 48 and 15%, respectively, for Tween 80; in addition, these lipids increased the enzyme activity by 6, 23 and 31%, respectively, in the Span 85 media, using purified pheophytin as substrate. Phytol showed a competitive inhibitory effect on chlorophyllase activity in both Span and Tween systems containing partially purified pheophytin substrate; however, phytol had an uncompetitive inhibitory effect on the enzyme activity in the S
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Calnexin association with lysosomal hydrolases is limited to overexpressed enzymes destined for secretionWilson, Daniel James, 1970. January 1996 (has links)
We investigated whether human lysosomal hydrolases, in common with secretory and plasma membrane glycoproteins, associate with the ER chaperone calnexin. Neither $ alpha$- or $ beta$-chains of $ beta$-hexosaminidase A, cathepsin D, nor the endogenous proteases cathepsins B or L associated with calnexin in COS-I cells. Hex $ alpha$-chains misfolded due to either the incorporation of azetidine-2-carboxylic acid, treatment with dithiothreitol, or the presence of a Tay-Sachs Disease mutation (leading to retention of Hex A $ alpha$-chains in the ER) also did not associate with calnexin. Chemical-crosslinking reagents or long-term labeling also failed to show a Hex A $ alpha$-chain association with calnexin. Lysosomal hydrolases also did not associate with the ER chaperone calreticulin. Surprisingly, $ alpha$-L-iduronidase and Hex A $ alpha$-chains associated with calnexin when overexpressed using a CMV promoter. The segregation of lysosomal hydrolases from secretory proteins thus occurs at an earlier stage than predicted. Hydrolase folding appears to be controlled by a pathway different from that used by secretory and plasma membrane glycoproteins.
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Regulation and characterization of microsomal epoxide hydrolase (Ephx1) in the female reproductive tract /Cheong, Wan-yee, Ana. January 2007 (has links)
Thesis (M. Med. Sc.)--University of Hong Kong, 2007.
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Structural and ligand-binding properties of a dual substrate specific enzymes from schizosaccharomyces pombe a dissertation /Garza, John Anthony. January 2009 (has links)
Dissertation (Ph.D.).--University of Texas Graduate School of Biomedical Sciences at San Antonio, 2009. / Vita. Includes bibliographical references.
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