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In Seong Choi Seung Gon Wi Se Ra Jung Darshan H. Patel Hyeun-Jong Bae 《Journal of Wood Science》2009,55(5):329-334
β-Glucosidase (β-1,4-D-glucoside glucohydrolase: EC.3.2.1.21) catalyzes the hydrolysis of β-glucosidic bonds between saccharides
and aryl or alkyl groups. A gene encoding β-glucosidase from Bacillus licheniformis KCTC 1918, an anaerobic spore-forming soil bacterium, was cloned and characterized. The structural gene for the β-glucosidase
consists of 1410 bp encoding 469 amino acid residues, and has a molecular weight of 53.4 kDa as estimated by sodium dodecyl
sulfate polyacrylamide gel electrophoresis with 12% separating gel. The enzyme activity was determined against pNPG as a substrate. The enzyme was optimally active at pH 6.0 (citrate-phosphate buffer) and 47°C. β-Glucosidase retained
100% of its original activity for 24 h. The activity of the enzyme was stimulated by glycerol and urea and was decreased by
Ca2+, Cu2+, Hg2+, Mg2+, and Mn2+. In particular, Cu2+ had the strongest negative effect on β-glucosidase activity. The purified β-glucosidase was active against pNPG and cellobiose. When the β-glucosidase was tested for cellulose hydrolysis, the supplement of β-glucosidase with cellulose
increased the glucose yield from pine wood powder by 139.8%. 相似文献
34.
Weston B. Johnson Wajira S. Ratnayake David S. Jackson Kyung‐Min Lee Timothy J. Herrman Scott R. Bean Stephen C. Mason 《Cereal Chemistry》2010,87(6):524-531
Dent corn (Zea mays L.) and sorghum (Sorghum bicolor L. Moench) sample sets representative of commonly grown hybrids and diverse physical attributes were analyzed for alkaline cooking performance. The influence of kernel characteristics including hardness, density, starch properties (thermal, pasting, and crystallinity), starch content, protein content, and prolamin content on alkaline cooking performance was also determined. Corn nixtamal moisture content was lower for hard, dense kernels with high protein contents; sorghum nixtamal moisture content was lower for kernels with low moisture contents and low starch relative crystallinities. Statistically significant (P < 0.05) regression equations showed that corn nixtamal moisture content was influenced by TADD (tangential abrasive dehulling device) index, kernel moisture content, starch content, and protein content; sorghum nixtamal moisture content was influenced by starch relative crystallinity, kernel moisture content, and abrasive hardness index. Pericarp removal was not strongly correlated with kernel characterization tests. Location (environmental) and hybrid (genetic) factors influenced most kernel characteristics and nixtamalization processing variables. 相似文献
35.
Ahn JH Kim HS Lee KJ Jeon S Kang SJ Sun Y Nuzzo RG Rogers JA 《Science (New York, N.Y.)》2006,314(5806):1754-1757
We developed a simple approach to combine broad classes of dissimilar materials into heterogeneously integrated electronic systems with two- or three-dimensional layouts. The process begins with the synthesis of different semiconductor nanomaterials, such as single-walled carbon nanotubes and single-crystal micro- and nanoscale wires and ribbons of gallium nitride, silicon, and gallium arsenide on separate substrates. Repeated application of an additive, transfer printing process that uses soft stamps with these substrates as donors, followed by device and interconnect formation, yields high-performance heterogeneously integrated electronics that incorporate any combination of semiconductor nanomaterials on rigid or flexible device substrates. This versatile methodology can produce a wide range of unusual electronic systems that would be impossible to achieve with other techniques. 相似文献
36.
Methylation methods for the quantitative analysis of conjugated linoleic acid (CLA) isomers in various lipid samples 总被引:8,自引:0,他引:8
Park SJ Park CW Kim SJ Kim JK Kim YR Park KA Kim JO Ha YL 《Journal of agricultural and food chemistry》2002,50(5):989-996
Precise methylation methods for various chemical forms of conjugated linoleic acid (CLA), which minimize the formation of t,t isomers and allylmethoxy derivatives (AMD) with the completion of methylation, were developed using a 50 mg lipid sample, 3 mL of 1.0 N H(2)SO(4)/methanol, and/or 3 mL of 20% tetramethylguanidine (TMG)/methanol solution(s). Free CLA (FCLA) was methylated with 1.0 N H(2)SO(4)/methanol (55 degrees C, 5 min). CLA esterified in safflower oil (CLA-SO) was methylated with 20% TMG/methanol (100 degrees C, 5 min), whereas CLA esterified in phospholipid (CLA-PL) was methylated with 20% TMG/methanol (100 degrees C, 10 min), followed by an additional reaction with 1.0 N H(2)SO(4)/methanol (55 degrees C, 5 min). Similarly, CLA esterified in egg yolk lipid (CLA-EYL) was methylated by base hydrolysis, followed by reaction with 1.0 N H(2)SO(4)/methanol (55 degrees C, 5 min). These results suggest that for the quantitative analysis of CLA in lipid samples by GC, proper methylation methods should be chosen on the basis of the chemical forms of CLA in samples. 相似文献
37.
Zeolites are crystalline nanoporous aluminosilicates widely used in industry. In order for zeolites to find applications as innovative materials, they need to be organized into large two- and three-dimensional (2D and 3D) arrays. We report that uniformly aligned polyurethane films can serve as templates for the synthesis of uniformly aligned 2D and possibly 3D arrays of silicalite-1 crystals, in which the orientations of the crystals are controlled by the nature of the polymers. We propose that the supramolecularly organized organic-inorganic composites that consist of the hydrolyzed organic products and the seed crystals are responsible for this phenomenon. 相似文献
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5-(2,6-difluorobenzyl)oxymethyl-5-methyl-3-(3-methylthiophen-2-yl)- 1,2-isoxazoline as a useful rice herbicide 总被引:1,自引:0,他引:1
Hwang IT Kim HR Jeon DJ Hong KS Song JH Cho KY 《Journal of agricultural and food chemistry》2005,53(22):8639-8643
5-(2,6-difluorobenzyl)oxymethyl-5-methyl-3-(3-methylthiophen-2-yl)-1,2-isoxazoline derivative was synthesized, and its herbicidal activity was assessed under glasshouse and flooded paddy conditions. 5-(2,6-Difluorobenzyl)oxymethyl-5-methyl-3-(3-methylthiophen-2-yl)-1,2-isoxazoline demonstrated good rice selectivity and potent herbicidal activity against annual weeds at 125 g of a.i. ha(-1) under greenhouse conditions. Soil application of this compound showed complete control of barnyard-grass to the fourth leaf stage at 250 g of a.i. ha(-1). Field trials indicated that this compound controlled annual weeds rapidly with a good tolerance on transplanted rice seedlings by post-emergence and soil application. This compound showed a low mammalian and environmental toxicity in various toxicological tests. 相似文献
40.
Six kinds of water-soluble chitosan were prepared by grafting aminofunctionality onto chitosan at the C-6 position, and their antimicrobial activities were investigated against three Gram-negative and three Gram-positive bacteria. Among the derivatives, dimethylaminoethyl-chitosan (DMAEC) has the highest potential to suppress the growth of bacteria. To elucidate detailed antimicrobial modes of action against bacteria, cell integrity, outer membrane (OM), and inner membrane (IM) permeabilization assays were investigated. When treated with DMAEC, the release of 260 nm absorbing materials quickly increased for both Escherichia coli and Staphylococcus aureus, but the absorbance value was different due to the difference in cell structures. In OM and IM permeabilization assays, DMAEC rapidly increased 1-N-phenylnaphthylamine uptake and the release of cytoplasmic beta-galactosidase via an increase in the permeability of OM and IM. Moreover, DMAEC90 prepared from 90% deacetylated chitosan had more activity than DMAEC50 prepared from 50% deacetylated chitosan, and these results revealed that the antimicrobial action of water-soluble chitosans was dependent on the degree of deacetylation and the substituted group. 相似文献