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1.
An endo-xylanase (1,4-β-d-xylanxylanohydrolase EC 3.2.1.8) was isolated from the culture filtrate of Paecilomyces varioti Bainier. The enzyme was purified 3.2 fold with a 60% yield by gel filtration and ion exchange chromatography. The purified enzyme had a molecular weight of 25,000 with a sedimentation coefficient of 2.2 S. The isoelectric point of the enzyme was 3.9. The enzyme was obtained in crystalline form. The optimum pH range was 5.5–7.0 and the temperature, 65°C. The Michaelis constant was 2.5 mg larchwood xylan/ml. The enzyme was found to degrade xylan by an endo mechanism producing arabinose, xylobiose, xylo- and arabinosylxylo-oligosaccharides, during the initial stages of hydrolysis. On prolonged incubation, xylotriose, arabinosylxylotriose and xylobiose were the major products with traces of xylotetraose, xylose and arabinose. 相似文献
2.
An endo-xylanase. 1,4-β-D-xylan xylanohydrolase (EC 3.2.1.8) from immature cucumber L. cv. Heinz 3534) seeds was partially purified using ammonium sulfate fractionation and chromatography on SP-Sephadex and Sephadex G-100 in order to determine its role in xylan metabolism during development. Attempts to further purify the enzyme using chromatography on DEAE-Sephadex, Bio-Gel HTP hydroxylapatite, Sephadex G-200 and con A-Sepharose 4B and native polyacrylamide gel electrophoresis resulted in a significant decrease or complete loss of enzyme activity. Endo-xylanase had a native molecular weight of 96 kDa as determined by gel filtration, exhibited optimal activity at pH 5.0 and 48°C, and was most stable from pH 4.0 to 5.0. Using beechwood 4- o-methyl-d -glucurono-d -xylan dyed with Remazol Brilliant Blue R as substrate, the K m was estimated to be 0.70 mg ml? 1. HgCl 2 at 1 m M inhibited endo-xylanase completely. Other metal ions inhibited the enzyme in the order Cu 2+ > Fe 3+ > Zn 2+ > Ca 2+ > Mn 2+. The ethanol-soluble products of endo-xylanase action on beechwood xylan were isolated and characterized by consecutive chromatography on Bio-Gel P-10 and P-2. The major reaction products were xylo-oligosaccharides [degree of polymerization (dp) > 10] but traces of xylobiose and free xylose were also isolated. The formation of xylo-oligosaccharides indicated that the reaction was catalyzed primarily by an endoxylanase. The partially pure enzyme had no activity towards other cell wall polysaccharides such as cellulose, carboxymethyl cellulose, sodium carboxyl cellulose, potato starch, orange pectin, polygalacturonic acid, arabinogalactan and β-giucan. However, it was able to hydrolyze larchwood and oat spelts xylan and a polysaccharide component from purified cucumber cell walls. The ability to utilize a substrate from cucumber cell walls supports the hypothesis that endo-xylanase is involved in the development of cucumber seeds. 相似文献
3.
A cellulase from the ruminal fungus Orpinomyces joyonii cloned in Escherichia coli was purified 88-fold by chromatography on High Q and hydroxyapatite. N-terminal amino acid sequence analyses confirmed that the cellulase represented the product of the cellulase gene Cel B2. The purified enzyme possessed high activity toward barley beta-glucan, lichenan, carboxymethyl cellulose (CMC), xylan, but not toward laminarin and pachyman. In addition, the cloned enzyme was able to hydrolyze p-nitrophenyl (PNP)-cellobioside, PNP-cellotrioside, PNP-cellotetraoside, PNP-cellopentaoside, but not PNP-glucopyranoside. The specific activity of the cloned enzyme on barley beta-glucan was 297 units/mg protein. The purified enzyme appeared as a single band in SDS-polyacrylamide gel electrophoresis and the molecular mass of this enzyme (58000) was consistent with the value (56463) calculated from the DNA sequence. The optimal pH of the enzyme was 5.5, and the enzyme was stable between pH 5.0 and pH 7.5. The enzyme had a temperature optimum at 40 degrees C. The K(m) values estimated for barley beta-glucan and CMC were 0.32 and 0.50 mg/ml, respectively. 相似文献
4.
Xylanase from Streptomyces xylophagus nov. sp. has been purified by ammonium sulfate fractionation and chromatography on DEAE-cellulose column. The purification of the enzyme was 276-fold with a yield of 18.6 % on the basis of the activity per weight of total nitrogen. The purified enzyme was homogeneous on moving-boundary electrophoresis. Optimum pH and temperature for the enzyme activity were 6.2 and 55~60°C, respectively. The enzyme was stable up to 40°C and in the range of pH from 5.3 to 7.3, but inactivated at higher than 50°C and at extreme pH values of 2.4 and 9.4. Hydrolyzed products of xylan by the enzyme were xylose and xylobiose. 相似文献
5.
Two different endo-1,4-beta-xylanases [1,4-beta-D-xylan xylanohydrolases, EC 3.2.1.8], named Xylanases I and III, were purified to homogeneity by gel filtration and ion exchange column chromatography from Driselase, a commercial enzyme preparation from Irpex lacteus (Polyporus tulipiferae). The purified enzymes were found to be homogeneous on polyacrylamide disc electrophoresis and their specific activities toward xylan were increased approximately 28.7 and 19.8 times, respectively. The activities of each enzyme were considerably inhibited by Hg2+, Ag+, and Mn2+. Their molecular weights were estimated to be approximately 38,000 and 62,000 by gel filtration and sodium dodecyl sulfate (SDS)-polyacrylamide electrophoresis, respectively. Their carbohydrate contents were 2.5% and 8.0% as glucose, and their amino acid composition patterns resembled each other, showing high contents of acidic amino acids, serine, threonine, alanine, and glycine. Both enzymes were most active at pH 6.0 but Xylanase I was more stable as to pH. Their optimum temperatures were 60 degrees C and 70 degrees C, respectively. Xylanase I split up to 34.5% of larchwood xylan whereas Xylanase III split only 18.9% of it. The products with the former were mainly xylose (X1), xylobiose (X2), and xylotriose (X3), whereas X2 and X3 were the main products with the latter. Both enzymes did not hydrolyze X2. Xylanase I produced almost equal quantities of X1 and X2 from X3, while Xylanase III did not attack this substrate. Both enzymes showed no activity toward glycans, other than xylan, such as starch, pachyman and Avicel (microcrystalline cellulose), except the almost one twentieth activity of Xylanase III toward sodium carboxymethyl cellulose (CMC). 相似文献
6.
A method of purification of endo-( 1 → 4)-β-xylanase (endoxylanase; EC 3.2.1.8) from the culture liquid of Geotrichum candidum 3C, grown for three days, is described. The enzyme, purified 23-fold, had a specific activity of 32.6 U per mg protein (yield,
14.4%). Endoxylanase was shown to be homogeneous by SDS-PAGE (molecular weight, 60 to 67 kDa). With carboxymethyl xylan as
the substrate, the optimum activity (determined viscosimetrically) was recorded at pH 4.0 (pI 3.4). The enzyme retained stability
at pH 3.0-4.5 and 30–45°C for 1 h. With xylan from birch wood, the hydrolytic activity of the enzyme (ability to saccharify
the substrate) was maximum at 50°C. In 72 h of exposure to 0.2 mg/ml endoxylanase, the extent of saccharification of xylans
from birch wood, rye grain, and wheat straw amounted to 10,12, and 7.7%, respectively. At 0.4 mg/ml, the extent of saccharification
of birch wood xylan was as high as 20%. In the case of birch wood xylan, the initial hydrolysis products were xylooligosaccharides
with degrees of polymerization in excess of four; the end products were represented by xylobiose, xylotriose, xylose, and
acid xylooligosaccharides. 相似文献
7.
A facultatively anaerobic, thermophilic, xylanolytic bacterium was isolated from a sample collected from the Diyadin Hot Springs,
Turkey. According to morphological, biochemical and molecular identification, this new strain was suggested to be representative
of the Anoxybacillus pushchinoensis and it was designated as Anoxybacillus pushchinoensis strain A8. It exhibited 97% similarity to 16S rRNA gene sequence of A. pushchinoensis and 77% DNA homology by DNA-DNA hybridization studies. Q-sepharose and CM-sepharose chromatography was used to purify an
extracellular xylanase to >90% purity from this species. The enzyme had a molecular mass of approximately 83 kDa. The enzyme
showed optimum activity at pH 6.5 and it was 96% stable over a broad pH range of 6.5–11 for 24 hours. The enzyme had optimum
activity at 55°C and it was 100% stable at temperature between 50–60°C up to 24 hours. Kinetic characterization of the enzyme
was performed at temperature optima (55°C) and V max and K
m were found to be 59.88 U/mg protein and 0.909 mg/mL, respectively. Oat spelt xylan but not xylooligosaccharides was degraded
by the enzyme and xylose was the only product detected from oat xylan degradation. This suggested that the enzyme was an exo-acting
xylanase. 相似文献
8.
Highly thermostable β-xylanase produced by newly isolated Thermomyces lanuginosus THKU-49 strain was purified in a four-step procedure involving ammonium sulfate precipitation and subsequent separation on
a DEAE-Sepharose fast flow column, hydroxylapatite column, and Sephadex G-100 column, respectively. The enzyme purified to
homogeneity had a specific activity of 552 U/mg protein and a molecular weight of 24.9 kDa. The optimal temperature of the
purified xylanase was 70°C, and it was stable at temperatures up to 60°C at pH 6.0; the optimal pH was 5.0–7.0, and it was
stable in the pH range 3.5–8.0 at 4°C. Xylanase activity was inhibited by Mn 2+, Sn 2+, and ethylenediaminetetraacetic acid. The xylanase showed a high activity towards soluble oat spelt xylan, but it exhibited
low activity towards insoluble oat spelt xylan; no activity was found to carboxymethylcellulose, avicel, filter paper, locust
bean gum, cassava starch, and p-nitrophenyl β- d-xylopyranoside. The apparent K
m value of the xylanase on soluble oat spelt xylan and insoluble oat spelt xylan was 7.3 ± 0.236 and 60.2 ± 6.788 mg/ml, respectively.
Thin-layer chromatography analysis showed that the xylanase hydrolyzed oat spelt xylan to yield mainly xylobiose and xylose
as end products, but that it could not release xylose from the substrate xylobiose, suggesting that it is an endo-xylanase. 相似文献
9.
An extra-cellular endo-hemicellulase (HC-II) from a culture isolate of the fungal plant pathogen Ceratocystis paradoxa ( CP2) was purified 147-fold by ammonium sulphate precipitation, DEAE-Sephadex chromatography, iso-electric focusing at pH 3–10, and gel-permeation chromatography. The resulting enzyme preparation, which contained traces of invertase, gave a single protein-band on disc electrophoresis at pH 8.4, and was active towards sucrose, hemicellulose, and carboxymethylcellulose (CMC). HC-II randomly degraded hemicelluloses from several different sources, to xylose and to arabinose-xylose and xylose oligosaccharides of d.p. 3–6 and 2–5, respectively, and also produced a degraded hemicellulose which precipitated from the digest solution. The precipitated hemicellulose contained less arabinose and uronic acid than the original hemicellulose. When redissolved by alkali-treatment, it was susceptible to further degradation by hemicellulases HC-I and HC-II. CMC was degraded by HC-II, mainly to D-glucose and cellobiose, with trace amounts of unidentified higher oligosaccharides, while cellobiose remained unattacked. Xylotriose (Xyl 3) was the lowest homologue of the xylose oligosaccharides attacked by HC-II at a significant rate, yielding xylobiose [Xyl 2; β-D-Xyl p-(1→4)-D-Xyl] and xylose. AraXyl 3AraXyl 5 were mainly hydrolysed to AraXyl 2, xylose, and Xyl 2 or Xyl 3. HC-II had a temperature optimum of 80°, and was stable for 1 h at temperatures up to 70°. The pH optimum was 5.1, and HC-II was stable between pH 5–10. The K m was 0.267 mg of hemicellulose B/ml. The effects of mercury(II) ions and high concentrations of xylose on the activity of HC-II were also investigated. 相似文献
10.
An xylanase producing alkaliphilic Micrococcus sp was isolated from an alkaline soda lake. Xylose and xylan induced enzyme production but no activity was detected when
it was grown using other carbohydrate sources. The level of xylanase production was higher in the presence of xylose than
in the presence of xylan. The enzyme was purified to homogeneity and its molecular weight was estimated to be 56 kD on SDS-PAGE.
The optimum temperature and pH for xylanase activity were 55°C and 7.5–9.0, respectively. Sixty per cent of the maximum activity
was displayed at pH 11. The enzyme was very stable in the pH range of 6.5–10 and up to a temperature of 40°C. Xylanase activity
was inhibited by Cu 2+ and Hg 2+.
Received 03 October 1997/ Accepted in revised form 03 February 1998 相似文献
11.
Summary Xylanase from Scytalidium thermophilum was immobilized on Eudragit L-100, a pH sensitive copolymer of methacrylic acid and methyl methacrylate. The enzyme was non-covalently
immobilized and the system expressed 70% xylanase activity. The immobilized preparation had broader optimum temperature of
activity between 55 and 65 °C as compared to 65 °C in case of free enzyme and broader optimum pH between 6.0 and 7.0 as compared
to 6.5 in case of free enzyme. Immobilization increased the t1/2 of enzyme at 60 °C from 15 to 30 min with a stabilization factor of 2. The Km and Vmax values for the immobilized and free xylanase were 0.5% xylan and 0.89 μmol/ml/min and 0.35% xylan and 1.01 μmol/ml/min respectively. An Arrhenius plot showed an increased value of activation energy for immobilized xylanase (227 kcal/mol)
as compared to free xylanase (210 kcal/mol) confirming the higher temperature stability of the free enzyme. Enzymatic saccharification
of xylan was also improved by xylanase immobilization. 相似文献
12.
Melanocarpus albomyces, a thermophilic fungus isolated from compost by enrichment culture in a liquid medium containing sugarcane bagasse, produced
cellulase-free xylanase in culture medium. The fungus was unusual in that xylanase activity was inducible not only by hemicellulosic
material but also by the monomeric pentosan unit of xylan but not by glucose. Concentration of bagasse-grown culture filtrate
protein followed by size-exclusion and anion-exchange chromatography separated four xylanase activities. Under identical conditions
of protein purification, xylanase I was absent in the xylose-grown culture filtrate. Two xylanase activities, a minor xylanase
IA and a major xylanase IIIA, were purified to apparent homogeneity from bagasse-grown cultures. Both xylanases were specific
for β-1,4 xylose-rich polymer, optimally active, respectively, at pH 6.6 and 5.6, and at 65°C. The xylanases were stable between
pH 5 to 10 at 50°C for 24 h. Xylanases released xylobiose, xylotriose and higher oligomers from xylans from different sources.
Xylanase IA had a M r of 38 kDa and contained 7% carbohydrate whereas xylanase IIIA had a M r of 24 kDa and no detectable carbohydrate. The K m for larchwood xylan (mg ml −1) and V max (μmol xylose min −1 mg −1 protein) of xylanase IA were 0.33 and 311, and of xylanase IIIA 1.69 and 500, respectively. Xylanases IA, II and IIIA showed
no synergism in the hydrolysis of larchwood glucuronoxylan or oat spelt and sugarcane bagasse arabinoxylans. They had different
reactivity on untreated and delignified bagasse. The xylanases were more reactive than cellulase on delignified bagasse. Simultaneous
treatment of delignified bagasse by xylanase and cellulase released more sugar than individual enzyme treatments. By contrast,
the primary cell walls of a plant, particularly from the region of elongation, were more susceptible to the action of cellulase
than xylanase. The effects of xylanase and cellulase on plant cell walls were consistent with the view that hemicellulose
surrounds cellulose in plant cell walls. 相似文献
13.
An extracellular alkaline carboxymethycellulase (CMCase) from Bacillus subtilis was purified by salt precipitation followed by anion-exchange chromatography using DEAE-Sepharose. The cell-free supernatant containing crude enzyme had a CMCase activity of 0.34 U/mg. The purified enzyme gave a specific activity of 3.33 U/mg, with 10-fold purification and an overall activity yield of 5.6%. The purified enzyme displayed a protein band on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) with an apparent molecular size of 30 kDa, which was also confirmed by zymogram analysis. The enzyme displayed multisubstrate specificity, showing significantly higher activity with lichenan and β-glucan as compared to carboxymethylcellulose (CMC), laminarin, hydroxyethylcellulose, and steam-exploded bagasse, and negligible activity with crystalline substrate such as Avicel and filter paper. It was optimally active at pH 9.2 and temperature 45°C. The enzyme was stable in the pH range 6–10 and retained 70% activity at pH 12. Thermal stability analysis revealed that the enzyme was stable in temperature range of 20°C to 45°C and retained more than 50% activity at 60°C for 30 min. The enzyme had a Km of 0.13 mg/ml and Vmax of 3.38 U/mg using CMC as substrate. 相似文献
14.
An amylase was purified from the culture filtrate of Termitomyces clypeatus by ammonium sulphate precipitation, DEAE-Sephadex chromatography and gel filtration on Bio-Gel P-200 column. The electrophoretically
homogeneous preparation also exhibited hydrolytic activity (in a decreasing order) on amylose, xylan, amylopectin, glycogen,
arabinogalactan and arabinoxylan. The enzyme had characteristically endo-hydrolytic activity on all the substrates tested
and no xylose, glucose, arabinose or glucuronic acid could be detected even after prolonged enzymatic digestion of the polysaccharides.
Interestingly the enzyme had similar pH optima (5.5), temperature optima (55°C), pH stability (pH 3–10) and thermal denaturation
kinetics when acted on both starch and xylan (larch wood) . K
m values were found to be 2.63 mg/ml for amylase and 6.25 mg/ml for xylanase activity. Hill’s plot also indicated that the
enzyme contained a single active site for both activities. Hg 2+ was found to be most potent inhibitor. Ca 2+, a common activator for amylase activity, appeared to be an inhibitor for this enzyme. Thus it appeared that the enzyme had
multisubstrate specificity acting as α-amylase on starch and also acting as xylanase on side chain oligosaccharides of xylan
containing α-linked sugars. 相似文献
15.
A potentially novel aerobic, thermophilic, and cellulolytic bacterium designated as Brevibacillus sp. strain JXL was isolated from swine waste. Strain JXL can utilize a broad range of carbohydrates including: cellulose,
carboxymethylcellulose (CMC), xylan, cellobiose, glucose, and xylose. In two different media supplemented with crystalline
cellulose and CMC at 57°C under aeration, strain JXL produced a basal level of cellulases as FPU of 0.02 IU/ml in the crude
culture supernatant. When glucose or cellobiose was used besides cellulose, cellulase activities were enhanced ten times during
the first 24 h, but with no significant difference between these two simple sugars. After that time, however, culture with
glucose demonstrated higher cellulase activities compared with that from cellobiose. Similar trend and effect on cellulase
activities were also obtained when glucose or cellobiose served as a single substrate. The optimal doses of cellobiose and
glucose for cellulase induction were 0.5 and 1%. These inducing effects were further confirmed by scanning electron microscopy
(SEM) images, which indicated the presence of extracellular protuberant structures. These cellulosome-resembling structures
were most abundant in culture with glucose, followed by cellobiose and without sugar addition. With respect to cellulase activity
assay, crude cellulases had an optimal temperature of 50°C and a broad optimal pH range of 6–8. These cellulases also had
high thermotolerance as evidenced by retaining more than 50% activity at 100°C after 1 h. In summary, this is the first study
to show that the genus Brevibacillus may have strains that can degrade cellulose. 相似文献
16.
An extracellular xylanase from the fermented broth of Bacillus cereus BSA1 was purified and characterized. The enzyme was purified to 3.43 fold through ammonium sulphate precipitation, DEAE cellulose
chromatography and followed by gel filtration through Sephadex-G-100 column. The molecular mass of the purified xylanse was
about 33 kDa. The enzyme was an endoxylanase as it initially degraded xylan to xylooligomers. The purified enzyme showed optimum
activity at 55°C and at pH 7.0 and remained reasonably stable in a wide range of pH (5.0–8.0) and temperature (40–65°C). The
K
m
and V
max
values were found to be 8.2 mg/ml and 181.8 μmol/(min mg), respectively. The enzyme had no apparent requirement of cofactors,
and its activity was strongly inhibited by Cu 2+, Hg 2+. It was also a salt tolerant enzyme and stable upto 2.5 M of NaCl and retained its 85% activity at 3.0 M. For stability and
substrate binding, the enzyme needed hydrophobic interaction that revealed when most surfactants inhibited xylanase activity.
Since the enzyme was active over wide range of pH, temperature and remained active in higher salt concentration, it could
find potential uses in biobleaching process in paper industries. 相似文献
17.
A novel, family GH10 enzyme, Xyn10B from Acidothermus cellulolyticus 11B was cloned and expressed in Escherichia coli. This enzyme was purified to homogeneity by binding to regenerated amorphous cellulose. It had higher binding on Avicel as compared to insoluble xylan due to the presence of cellulose-binding domains, CBM3 and CBM2. This enzyme was optimally active at 70 °C and pH 6.0. It was stable up to 70 °C while the CD spectroscopy analysis showed thermal unfolding at 80 °C. Xyn10B was found to be a trifunctional enzyme having endo-xylanase, arabinofuranosidase and acetyl xylan esterase activities. Its activities against beechwood xylan, p-Nitrophenyl arabinofuranoside and p-Nitrophenyl acetate were found to be 126,480, 10,350 and 17,250 U μmol−1, respectively. Xyn10B was highly active producing xylobiose and xylose as the major end products, as well as debranching the substrates by removing arabinose and acetyl side chains. Due to its specific characteristics, this enzyme seems to be of importance for industrial applications such as pretreatment of poultry cereals, bio-bleaching of wood pulp and degradation of plant biomass. 相似文献
18.
The gene encoding a xylanase from Geobacillus sp. 71 was isolated, cloned, and sequenced. Purification of the Geobacillus sp 7.1 xylanase, XyzGeo71, following overexpression in E. coli produced an enzyme of 47 kDa with an optimum temperature of 75°C. The optimum pH of the enzyme is 8.0, but it is active over
a broad pH range. This protein showed the highest sequence identity (93%) with the xylanase from Geobacillus thermodenitrificans NG80-2. XyzGeo71 contains a catalytic domain that belongs to the glycoside hydrolase family 10 (GH10). XyzGeo71 exhibited
good pH stability, remaining stable after treatment with buffers ranging from pH 7.0 to 11.0 for 6 h. Its activity was partially
inhibited by Al 3+ and Cu 2+ but strongly inhibited by Hg 2+. The enzyme follows Michaelis–Menten kinetics, with K m and V max values of 0.425 mg xylan/ml and 500 μmol/min.mg, respectively. The enzyme was free from cellulase activity and degraded xylan
in an endo fashion. The action of the enzyme on oat spelt xylan produced xylobiose and xylotetrose. 相似文献
19.
The novel fungus Aspergillus niveus RS2 isolated from rice straw showed relatively high xylanase production after 5 days of fermentation. Of the different xylan-containing
agricultural by-products tested, rice husk was the best substrate; however, maximum xylanase production occurred when the
organism was cultured on purified xylan. Yeast extract was found to be the best nitrogen source for xylanase production, followed
by ammonium sulfate and peptone. The optimum pH for maximum enzyme production was 8 (18.2 U/ml); however, an appreciable level
of activity was obtained at pH 7 (10.9 U/ml). Temperature and pH optima for xylanase were 50°C and 7.0, respectively; however
the enzyme retained considerably high activity under high temperature (12.1 U/ml at 60°C) and high alkaline conditions (17.2 U/ml
at pH 8 and 13.9 U/ml at pH 9). The enzyme was strongly inhibited by Hg 2+, while Mn 2+ was slight activator. The half-life of the enzyme was 48 min at 50°C. The enzyme was purified by 5.08-fold using carboxymethyl-sephadex
chromatography. Zymogram analysis suggested the presence of a single candidate xylanase in the purified preparation. SDS-PAGE
revealed a molecular weight of approximately 22.5 kDa. The enzyme had K
m and V
max values of 2.5 and 26 μmol/mg per minute, respectively. 相似文献
20.
In this study, the extracellular enzyme activity of Bacillus sp. A8-8 was detected on LB agar plates containing 0.5% of the following substrates: carboxymethylcellulose (CMC), xylan,
cellulose, and casein, respectively. The β-1,3-1,4 glucanase produced from Bacillus sp. A8-8 was purified by ammonium sulfate and hydrophobic chromatography. The molecular size of the protein was estimated
by SDS-PAGE as approximately 33 kDa. The optimum pH and temperature for the enzyme activity were 6.0 and 60°C, respectiveley.
However, enzyme activity was shown over a broad range of pH values and temperatures. The purified β-1,3-1,4 glucanase retained
over 70% of its original activity after incubation at 80°C for 2 h, and showed over 40% of its original activity within the
pH range of 9 to 12. This suggests that β-1,3-1,4 glucanase from Bacillus sp. A8-8 is thermostable and alkalistable. In addition, β-1,3-1,4 glucanase had higher substrate specificity to lichenan
than to CMC. Finally the activity of the endoglucanase was inhibited by Fe 3+, Mg 2+, and Mn 2+ ions. However Co 2+ and Ca 2+ ions were increased its activity.
These authors contributed equally to this work. 相似文献
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