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991.
Cornett Catherine A.G.; Fang Tsuei-Yun; Reilly Peter J.; Ford Clark 《Protein engineering, design & selection : PEDS》2003,16(7):521-529
Aspergillus niger glucoamylase (GA) consists mainly of two forms,GAI [from the N-terminus, catalytic domain + linker + starch-bindingdomain (SBD)] and GAII (catalytic domain + linker). These domainswere shuffled to make RGAI (SBD + linker + catalytic domain),RGAIL (SBD + catalytic domain) and RGAII (linker + catalyticdomain), with domains defined by function rather than by tertiarystructure. In addition, Paenibacillus macerans cyclomaltodextringlucanotransferase SBD replaced the closely related A.nigerGA SBD to give GAE. Soluble starch hydrolysis rates decreasedas RGAII GAII GAI > RGAIL RGAI GAE. Insoluble starchhydrolysis rates were GAI > RGAIL > RGAI >> GAE RGAII > GAII, while insoluble starch-binding capacitieswere GAI > RGAI > RGAIL > RGAII > GAII > GAE.These results indicate that: (i) moving the SBD to the N-terminusor replacing the native SBD somewhat affects soluble starchhydrolysis; (ii) SBD location significantly affects insolublestarch binding and hydrolysis; (iii) insoluble starch hydrolysisis imperfectly correlated with its binding by the SBD; and (iv)placing the P.macerans cyclomaltodextrin glucanotransferaseSBD at the end of a linker, instead of closely associated withthe rest of the enzyme, severely reduces its ability to bindand hydrolyze insoluble starch. Received June 20, 2002; revised May 23, 2003; accepted June 6, 2003. 相似文献
992.
The aims of this study were to determine whether vaccenic acid (VA; t11–18∶1) is converted to c9,t11-CLA in human mammary (MCF-7) and colon (SW480) cancer cell lines and whether VA influences cell viability and other CLA-bioresponsive
markers. When cells were incubated in the presence of VA at concentrations of 5 to 20 μg/mL, both VA and c9,t11-CLA increased in cellular lipids in a dose-dependent manner. After 4 d of incubation of SW480 and MCF-7 cells with VA (20
μg/mL), c9,t11-CLA increased from undetectable levels to 8.57 and 12.14 g/100 g FAME in cellular lipids, respectively. VA supplementation
for 4 d at 5, 10, and 15 μg/mL had no effect on cell growth, whereas 20 μg/mL significantly (P<0.05) reduced cell growth in both cell lines. VA (20 μg/mL) treatment induced DNA fragmentation and significantly (P<0.05) depeleted cytosolic GSH levels in the SW480 cell line after 4 d of incubation, suggesting that apoptosis was the mode
of cell death induced by VA. Both VA and c9,t11-CLA reduced (P<0.05) total ras expression in SW480 cells. 14C-Arachidonic acid uptake into the MG fraction was significantly increased (P<0.05) in both cell lines while uptake into the phospholipid fraction decreased in response to VA. VA treatment significantly
(P<0.05) increased 8-epi-prostaglandin F2α in both cell lines. The data indicate that growth suppression and cellular responses of both cells lines are likely mediated
by VA desaturation to c9,t11-CLA via Δ9-desaturase. 相似文献
993.
Food Drying and Dewatering 总被引:3,自引:0,他引:3
Catherine Bonaui Elisabeth Dumoulin Anne-Lucie Raoult-Wack Z. Berk J.J. Bimbenet F. Courtois G. Trystram J. Vasseur 《Drying Technology》1996,14(9):2135-2170
Food drying and dewatering raises a growing interest because of increasing requirements in quality, specially in the production of ingredients and additives for food formulation. Heat and mass transfers, as well as mechanical phenomena and reactions kinetics induced by these transfers must be more and more carefully controlled during drying and storage.
This chapter relates recent advances in
- drying of solids
- spray-drying
- drum-dryine
- superheateded steam drying
- osmotice dehydration
- hot oil immersion drying 相似文献
This chapter relates recent advances in
- drying of solids
- spray-drying
- drum-dryine
- superheateded steam drying
- osmotice dehydration
- hot oil immersion drying 相似文献
994.
Liquid velocity profiles in a bubble column were measured with the aid of a hot-film anemometer. Two different types of profiles were detected that were characterized by the formation of a boundary layer at the column wall. Under slow flow conditions, the boundary layer is large and controls the liquid velocity profile, but in turbulent flow the boundary layer is very small and has no significant effect on the velocity profile. Microscopic and macroscopic balances were used to predict both the liquid velocity profile and the average liquid velocity.
The effect of the liquid velocity profile and average velocity on axial dispersion and gas-hold-up are analyzed and design procedures are recommended. 相似文献
The effect of the liquid velocity profile and average velocity on axial dispersion and gas-hold-up are analyzed and design procedures are recommended. 相似文献
995.
Chunpeng Wang Fuxiang Chu Alain Guyot Catherine Gauthier Fernande Boisson 《应用聚合物科学杂志》2006,101(6):3927-3941
Two kinds of hybrid acrylic–polyurethane (PUA) latexes are compared according to their synthesis and properties. The acrylic part is a copolymer of styrene, methyl methacrylate, and butyl acrylate. The PUAs are based on the polycondensation of isophorone diisocyanate and poly(propylene glycol) using butanediol and ethylene diamine as chain extenders. The first class result from the polymerization of miniemulsions of solutions of PU in the mixture of monomers using benzoyl peroxide as an initiator at 80°C. In the second class PUs modified by neutralized dimethylolpropionic acid are used as seeds and emulsifiers for emulsion polymerization of the monomer mixtures initiated with azobisisobutyronitrile at 75°C. The polymerization kinetics are compared, as well as the morphology of the latex particles. Films are obtained upon coalescence of these latexes, and the surface composition of these films and their tensile properties are studied. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3927–3941, 2006 相似文献
996.
Summary A modified Rosenmund-Kuhnhenn method has been described in which, with one easily prepared and stable reagent, consistent
and repeatable iodine numbers are obtained in one minute with all ordinary nonconjugated fats and oils.
Presented before the American Oil Chemists' Society Meeting, Chicago, November 2, 1949. 相似文献
997.
The relationship between host plant glucosinolate profile and feeding and growth of the Bertha armyworm,Mamestra configurata Walker was investigated using eight cultivated rape and mustard varieties. Mean larval weights of neonates reared on intact rosette-stage plants were significantly different on the different species in the orderBrassica juncea <Sinapis alba <B. napus <B. campestris. WhileB. juncea was least preferred,S. alba was significantly more attractive to neonate larvae in choice tests. Relative consumption and growth rates of fourth-instar larvae were also reduced onB. juncea foliage. Other differences were dependent on the plant growth stage. Neonate preference was not correlated to total glucosinolate levels, but rather to the concentrations of isothiocyanate-releasing glucosinolates. However, the relationship between consumption and glucosinolate levels was inconsistent. Relative growth rate was negatively correlated to total glucosinolate content for stage 3 and 4 foliage—mainly due to the concentration of isothiocyanatereleasing glucosinolates. The relative importance of isothiocyanate-releasing glucosinolates was verified by rearing neonates on meridic diets containing equimolar concentrations of sinigrin, its metabolite, allyl isothiocyanate, and indole-3-carbinol, metabolite of 3-indolylmethyl glucosinolate. Sinigrin and allyl isothiocyanate in the diet produced virtually identical negative weight vs. concentration regression lines. No such dose-response effect was observed with indole-3-carbinol. The data suggest that foliar isothiocyanate-releasing glucosinolates may provide some degree of plant protection from polyphagous insects. 相似文献
998.
Pierre D. Harvey 《Journal of Inorganic and Organometallic Polymers》2004,14(4):211-226
This short review focuses on recent advances in the syntheses, characterization and structures of coordination and organometallic complexes of upper-rim functionalized calix[4]arenes that form either small oligomers or polymers. This field is very limited, presumably due to the lack of X-ray data or reliable characterization that demonstrates the presence of oligomers or polymers. Nonetheless, the few published works already clearly demonstrate the immense versatility of the calix[4]arene macrocycle as it forms polymeric materials via coordination bondings with transition metals. 相似文献
999.
Laurent Delannoy Norbert Weiher Nikolaos Tsapatsaris Angela M. Beesley Luanga Nchari Sven L. M. Schroeder Catherine Louis 《Topics in Catalysis》2007,44(1-2):263-273
The origin of CO oxidation performance variations between three different supported Au catalysts (Au/CeO2, Au/Al2O3, Au/TiO2) was examined by in situ XAFS and DRIFTS measurements. All samples were prepared identically, by deposition-precipitation of an aqueous Au(III) complex
with urea, and contained the same gold loading (~1 wt %). The as-prepared supported Au(III) precursors exhibited different
reduction behaviour during exposure to the CO/O2/He reaction mixture at 298 K. The reducibility of the Au(III) precursor was found to decrease as a function of the support
material in the order: titania > ceria > alumina. The as-prepared samples were inactive catalysts, but Au/TiO2 and Au/CeO2 developed catalytic activity as the reduction of Au(III) to metallic Au proceeded. Au/Al2O3 remained inactive. The developed catalytic CO oxidation activity at 298 K varied as a function of the support as follows:
titania > ceria > alumina ~ 0. The EXAFS of samples pretreated in air at 773 K and in H2 at 573 K reveals the presence of only metallic particles for Au/TiO2 and Au/Al2O3. Au(III) supported on CeO2 remains unreduced after calcination, but reduces during the treatment with H2. CO oxidation experiments performed at 298 K with the activated samples show that the presence of metallic gold is necessary
to obtain active catalysts (Au/CeO2 is not active after calcination) and that the reducible supports facilitate the genesis of active catalysts, while metallic
gold particles on alumina are not active. 相似文献
1000.
Heeyoung Yoon Harvey W. Blanch 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1977,27(1):260-268
Competition between two microorganisms in continuous culture for multiple substrates is examined. The competitive elimination principle of Gauss applies when two organisms compete for one growth-limiting substrate. If two substrates are present, and microbial growth depends on both (double substrate limitation), then both organisms may coexist in a stable steady state. The range of microbial parameters over which this steady state occurs is examined. 相似文献