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1.
β-Glucosidase was covalently immobilized alone and coimmobilized with cellulase using a hydrophilic polyurethane foam (Hypol®FHP 2002). Immobilization improved the functional properties of the enzymes. When immobilized alone, the Km for cellobiose of β-glucosidase was decreased by 33% and the pH optimum shifted to a slightly more basic value, compared to the free enzyme. Immobilized β-glucosidase was extremely stable (95% of activity remained after 1000 h of continuous use). Coimmobilization of cellulase and β-glucosidase produced a cellulose-hydrolyzing complex with a 2.5-fold greater rate of glucose production for soluble cellulose and a four-fold greater increase for insoluble cellulose, compared to immobilized cellulase alone. The immobilized enzymes showed a broader acceptance of various types of insoluble cellulose substrates than did the free enzymes and showed a long-term (at least 24 h) linear rate of glucose production from microcrystalline cellulose. The pH optimum for the coimmobilized enzymes was 6.0. This method for enzyme immobilization is fast, irreversible, and does not require harsh conditions. The enhanced glucose yields obtained indicate that this method may prove useful for commercial cellulose hydrolysis. 相似文献
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3.
Literature reports have described the covalent coupling of the primary amine-containing anticancer drug, adriamycin, to polymeric supports through the amine group on the drug. These reports also have described drug mechanism studies with the immobilized adriamycin, where the release of the drug would undermine the validity of the conclusions. In the present paper, detailed experimental conditions are given for preparation of nonwater-soluble particles of polyvinyl alcohol by crosslinking water-soluble polyvinyl alcohol with 1,4-benzenedicarboxaldehyde, and for activation with cyanuric chloride and covalent attachment of adriamycin. The expected stability of this drug-support linkage against hydrolytic cleavage is compared mechanistically to that expected for less stable coupling through a carbamate linkage or for less stable coupling via an azomethine link. 相似文献
4.
Hiroshi Ooshima Masahiro Kurakake Jyoji Kato Yoshio Harano 《Applied biochemistry and biotechnology》1991,31(3):253-266
Hydrolysis of pure cellulose Avicel has been carried out, using Meicelase from Trichoderma viride, where the enzymatic activity of cellulase adsorbed on cellulose and its changes during the hydrolysis were investigated. A rapid drop of the hydrolysis rate during the reaction, that is always observed in enzymatic hydrolysis of cellulose, could be explained by a decline of specific activity of adsorbed enzyme, and it was implied that the decline results from a loss of synergistic action between endoglucanase and exoglucanase. An empirical equation expresses the change of hydrolysis rate during the reaction and also shows that the change of the hydrolysis rate is caused by the decline of the specific enzymatic activity of adsorbed enzyme. 相似文献
5.
Effectiveness of cross-linked phyllosilicates for intercalative immobilization of soybean lipoxygenase 总被引:1,自引:0,他引:1
A novel procedure was developed to intercalate enzymes into dispersed phyllosilicates that were cross-linked with silicate polymers formed by the hydrolysis of tetramethyl orthosilicate (TMOS). Lipoxygenase (LOX) intercalated into cross-linked phyllosilicates exhibited high enzymatic activity. The enzyme-phyllosilicate composite prepared by this procedure had an improved pore network. Alkylamines were used to occupy the charge sites of the phyllosilicate, which increased the hydrophobicity of the phyllosilicate and reduced charge-charge interaction between LOX and the phyllosilicate. The amount of macropores and the enzymatic activity of the lipoxygenase-phyllosilicate composites increased with an increase in the ratio of trimethylammonium (TMA)-phyllosilicate to cross-linking reagent TMOS. LOX intercalatively immobilized into phyllosilicates displayed good storage stability and reusability at ambient temperature. 相似文献
6.
Chetsumon Aparat Umeda Fusako Maeda Isamu Yagi Kiyohito Mizoguchi Tadashi Miura Yoshiharu 《Applied biochemistry and biotechnology》1998,(1):249-256
A photobioreactor was constructed using anchored polyurethane foam strips (1 x 1 x 40 cm) fixed onto a stainless-steel ring
to prevent flotation, as a biomass support material (BSM). This type of reactor was named a seaweed-type bioreactor. A filamentous
cyanobacterium, Scytonema sp. TISTR 8208, which produces a novel cyclic dodecapeptide antibiotic, was immobilized in seaweed-type
photobioreactor and cultivated with air containing 5% CO2 sparged at a gas flow rate of 250 mL/min under illumination at a light intensity of 200 μmol photon m-2s-1. The antibiotic produced in the seaweed-type photobioreactor was purified by HPLC and examined regarding its spectrum and
mode of action. The antibiotic effectively inhibited the growth of Gram-positive bacteria, pathogenic yeasts, and filamentous
fungi, but it had only a weak effect on Gram-negative bacteria. Scanning electron micrograph analysis showed that the most
characteristic change was swelling of the cells after exposure to the antibiotic. The antibiotic seems to alter the conformation
of the microbial cell membrane, thereby changing its permeability, leading to osmotic shock. 相似文献
7.
Ko Samuel Loha Veara Prokop Ales Tanner Robert D. 《Applied biochemistry and biotechnology》1998,(1):547-558
The major sweet potato root protein, sporamin (which comprises about 80–90% of the total protein mass in the sweet potato)
easily foams in a bubble/foam-fractionation column using air as the carrier gas. Control of that foam fractionation process
is readily achieved by adjusting two variables: bulk solution pH and gas superficial velocity. Varying these parameters has
an important role in the recovery of sporamin in the foam. Changes in the pH of the bulk solution can control the partitioning
of sporamin in the foam phase from that in the bulk phase. A change in pH will also affect the amount of foam generated. The
pH varied between 2.0 and 10.0 and the air superficial velocities (V0) ranged between 1.5 and 4.3 cm/s. It was observed in these ranges that, as the pH increased, the total foamate volume decreased,
but the foamate protein (mainly sporamin) concentration increased. On the other hand, the total foamate volume increased significantly
as the air superficial velocity increased, but the foamate concentration decreased slightly. The minimum residual protein
concentration occurred at pH 3.0 and Vo = 1.5 cm/s. On the other hand, the maximum protein mass recovery occurred at pH 3.0 and at Vo = 4.3 cm/s. 相似文献
8.
A new type of reactor, the attrition bioreactor, has been developed to increase the rate of the enzymatic hydrolysis of cellulose
and also to cut pretreatment costs. It was found that the attrition bioreactor could be operated continuously or semicontinuously
in conjunction with a membrane filter to produce a high cellulose conversion rate and low enzyme consumption. The membrane
filter served to contain the enzyme and cellulose within the reactor while allowing sugar to permeate as a product. 相似文献
9.
Kawakami Mitsuyasu Koya Hidekazu Gondo Shinichiro 《Applied biochemistry and biotechnology》1991,(1):211-219
A glucose electrode was fabricated by immobilizing glucose oxidase covalently onto a platinized platinum electrode. The sensor
showed rapid response with response time of 2—4 s, and also the linear response to the glucose concentration, ranging from
2 x 10-3 to 5 mM. The sensitivity was found to be correlated with the surface area of a base electrode used. 相似文献
10.
Urease has been purified from the seeds of Cajanus Cajan. The purification process involves three solvent extraction steps followed by DEAE-cellulose column chromatography. The specific activity of the purified enzyme is found to be 1920 U/mg with the recovery of 8%. The application of the purified enzyme in a biosensor construction is discussed. 相似文献
11.
Jeffries Thomas W. Yang Vina W. Davis Mark W. 《Applied biochemistry and biotechnology》1998,(1):257-265
Xylanases are commonly assayed by the dinitrosalicylic acid (DNS) or the arsenomolybdate (ARS) method. However, specific activities
are many times higher with DNS than with ARS. This is because the DNS assay is more reactive and the ARS assay is less reactive
with xylooligosaccharides than with xylose. Xylose is often used as a standard, even though oligosaccharides are prevalent,
so the DNS method overestimates and the ARS method underestimates specific activity. Ion chromatography, with pulsed amperometric
detection, separates and measures all products and intermediates, but quantitation on a molar basis is difficult, because
few xylooligosaccharide response factors are known. This report directly compares these three assay methods for the assay
of xylanase activities. 相似文献
12.
John D. Wright Charles E. Wyman Karel Grohmann 《Applied biochemistry and biotechnology》1988,18(1):75-90
Simultaneous saccharification and fermentation (SSF) processes for producing ethanol from lignocellulose are capable of improved
hydrolysis rates, yields, and product concentrations compared to separate hydrolysis and fermentation (SHF) systems, because
the continuous removal of the sugars by the yeasts reduces the end-product inhibition of the enzyme complex. Recent experiments
using Genencor 150L cellulase and mixed yeast cultures have produced yields and concentrations of ethanol from cellulose of
80% and 4.5%, respectively. The mixed culture was employed because B.clausenii has the ability to ferment cellobiose (further reducing end-product inhibition), while the brewing yeastS. cerevisiae provides a robust ability to ferment the monomeric sugars. These experimental results are combined with a process model to
evaluate the economics of the process and to investigate the effect of alternative processes, conditions, and organisms. 相似文献
13.
Azmi Telefoncu Erhan Dlnckaya Klaus D. Vorlop 《Applied biochemistry and biotechnology》1990,26(3):311-317
Pancreatic lipase (EC 3.1.1.3) was immobilized by entrapping in a commercial preparation of acrylic/methacrylic acid ester-based copolymer (Eudragit E 30 D). The activity of the immobilized lipase beads with a diameter of 1.5-2.0 mm was found to be lower than that of the free lipase. The optimum pH was shifted to the alkaline region and the thermal stability increased, whereas the optimum temperature level remained unchanged. The most important reason for the decreased activity was diffusion limitations. The diffusion of the substrate and products became more pronounced, and lipolytic activity increased upon addition of n-hexane into the reaction medium. The storage and operational stabilities of the immobilized lipase were investigated, and both characteristics were found to be increased when compared to the free enzyme. Furthermore, mechanical or magnetic stirring during the operation were found to have no influence on the carrier-matrix as determined by nephelometric measurements. 相似文献
14.
Patricia M. G. Paiva Luana C. B. B. Coelho 《Applied biochemistry and biotechnology》1992,36(2):113-118
Two additional electrophoretically distinct molecular forms, isoforms (iso) 2 and 3, with lectin properties were isolated
fromCratylia mollis Mart, seeds (FABACEAE), by extraction with 0.15M NaCl and ammonium sulfate fractionation, followed by chromatography on Sephadex
G-75 and Bio-Gel P-200 (iso 2), as well as CM-Cellulose and Sephadex G-75 (iso 3). Both isoforms were human group nonspecific
and showed distinct specificity. Polyacrylamide gel electrophoresis resolved iso 2 and 3 in polypeptides of apparent mol wts
60 and 31 kDa, respectively; a distinct isoelectric focusing pattern was obtained for iso 2 and 3, under denaturing and reducing
conditions. 相似文献
15.
de Castro Heizir F. Napoleão Diovana A. S. Oliveira Pedro C. 《Applied biochemistry and biotechnology》1998,(1):667-675
Several reports exist in the literature citing the decrease in conversion rates of organic-phase catalytic synthesis reactions
when acetic acid is present as a reaction component. This inhibition is thought to result from damage to either the hydration
layer-protein interaction or the overall enzyme structure. In this work, the inhibitory effect of acetic acid on lipase enzyme
activity was ameliorated by conducting syntheses under acetic acid-limiting conditions in a fed-batch system, resulting in
higher product yields. Periodic additions of acetic acid at levels of 40 mM or less gave maximum yields of 65% conversion for the reaction of citronellol and acetic acid to form citronellyl acetate.
The enzyme used was a fungal lipase fromMucor miehei, and was immobilized on macroporous synthetic resin (a Novo lipozyme Novo Nordisk, Denmark). These results represent a fourfold
improvement over batch runs reported in the literature for direct esterification of terpene alcohol with acetic acid using
lipozyme as a catalytic agent. 相似文献
16.
J. Sereikaité D. Iljasevičiené G. Dienys H. Danilčenko V. Gavrilova 《Applied biochemistry and biotechnology》1993,43(2):153-160
Ascorbate oxidase fromCucurbita sp. was isolated by ammonium sulfate precipitation and DEAE-dextran-silochrome column chromatography. The thermal and pH stabilities
of the purified enzyme were investigated. TheK
M forl-ascorbic acid (1.5 mM) and chlorohydroquinone (0.37 mM) was determined. Substrate specificity of ascorbate oxidase was investigated and compared with those of laccases fromCoriolus hirsutus andCerrena maxima. Ascorbate oxidase was covalently bound to a polymeric membrane and used in an enzyme electrode for ascorbic acid. 相似文献
17.
E. Rapatz A. Travnicek G. Fellhofer F. Pittner 《Applied biochemistry and biotechnology》1988,19(3):223-234
beta-Glucuronidase (EC 3.2.1.31) was immobilized on various organic and inorganic carriers by different methods. Optimum coupling conditions have been worked out. The immobilization were characterized and compared to each other. Parameters resulting in most stable preparations with high activities are discussed. 相似文献
18.
Goldstein Irving S. Bayat-Makooi Fred Sabharwal H. S. Singh T. M. 《Applied biochemistry and biotechnology》1989,(1):95-106
Satisfactory separation of either hydrochloric or sulfuric acid from sugars in wood hydrolyzates by application of membrane
technology is technically feasible. The permeability of disaccharides is less than 1% that of the acids. Acid flux in diffusion
dialysis is only 6% of acid flux at optimum current density in electrodialysis. Critical parameters for economic feasibility
are acid to wood ratio in hydrolysis, current efficiency, and membrane service life. Best case estimates project total costs
for sulfuric acid recovery and loss of about $0.02 per pound of glucose produced. 相似文献
19.
Synthesis of Cyclodextrin Glucosyl Transferase byBacillus cereus for the production of cyclodextrins
R. Jamuna N. Saswathi R. Sheela S. V. Ramakrishna 《Applied biochemistry and biotechnology》1993,43(3):163-176
A potent indigenous bacillus isolate identified asBacillus cereus (RJ-30) was found to produce Cyclodextrin Glucosyl Transferase (CGTase) extracellularly. Process optimization of various
fermentation parameters has been established for optimal growth of bacillus and the maximum enzyme synthesis. The organism
had the highest specific growth rate (0.7μ) with a generation time of 1 h in glucose containing medium at the conditions of
pH 7.0, 37°C at 300 rpm, 1.5 vvm of agitation, and aeration. At these conditions, it exhibited the maximum activity of 54
U/mL at the synthesis rate of 2.7 U/L/h. CGTase was produced from the early exponential growth and peaked during the midsporulating
stage of about 16 h thereafter maintained at the same level of 50 U/mL. Saccharides containing media were better inducers
than starch, and the influence of carbohydrate substrates has shown that enzyme synthesis is promoted by xylose (65 U/mL)
and, more remarkably, by the supplementation of wheat bran extract in glucose medium (106 U/mL). This organism produced CGTase
stably in a chemostat culturing over a period of 400 h with a maximum productivity of 5.4 kU/L/h (threefold higher than obtained
in batch culturing [1.75 kU/L/h]). Comparatively, CGTase was produced by immobilized cells in a continuous fluidized bed reactor
for over approx 360 h, at a relatively high dilution rate of 0.88 h−1 resulting in the productivity of 23.0 kU/L/h. 相似文献
20.
Kaster Jeffrey A. Michelsen Donald L. Velander William H. 《Applied biochemistry and biotechnology》1990,(1):469-484
A microbubble dispersion (MBD) was used to supply oxygen for aerobic fermentations in a standard 2 L stirred tank fermenter.
The microbubble dispersion was formed using only surfactants produced naturally. Growth rates ofSaccharomyces cerevisiae cultures were found to be equal or greater with MBD sparging than with gas sparging. The oxygen transfer coefficent with
MBD sparging was found to be 190/h and independent of impeller speed from 100–580 rpm. The oxygen transfer coefficient with
air sparging rose from 55 to 132/h over the same range of impeller speeds. Power requirements for the fermenter systems were
estimated. 相似文献