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1.
Zahoor Qadir Samra Sadaf Shabir Zainab Rehmat Mariam Zaman Aqsa Nazir Nadia Dar Muhammad Amin Athar 《Applied biochemistry and biotechnology》2010,162(3):671-686
Human serum paraoxonase 1 (PON1) is known as an antioxidant and is also involved in the detoxification of many compounds.
In this study, a novel purification strategy was employed to purify the PON1 by using cholesterol-conjugated magnetic nanoparticles.
Magnetic nanoparticles were synthesized and conjugated with cholesterol through diazotized p-aminohippuric acid. In Fourier transform infrared spectrum of cholesterol-p-aminohippuric acid-Fe3O4 nanoparticles, the appearance of peaks at 3,358.3, 1,645 cm−1, and at 2,334.9 cm−1 confirmed the conjugation. The molecular weight of purified PON1 was nearly 45 kDa on sodium dodecyl sulfate (SDS)–polyacrylamide
gel electrophoresis (PAGE), and isoelectric point was 5.3. The specific activity was 438 U mg−1 protein, and the purification fold was 515 with 73% yield. The K
m values were 1.3 and 0.74 mM with paraoxon and phenyl acetate, respectively. Western blot of 2D-PAGE confirmed the homogeneity
and stability of the enzyme. Mg+2, Mn+2, glycerol, (NH4)2SO4, PEG 6000, Triton X-100, and phenylmethylsulfonyl fluoride did not show any effect on activity. Pb+2, Co+2, Zn2+, ethanol, β-mercaptoethanol, and acetone reduced the activity while Ni2+, Cd2+, Cu2+, iodoacetic acid, SDS, dimethylformamide, DMSO inhibited the activity. In vitro enzyme activity was slightly reduced by acetyl
salicylic and acetaminophen and reduced 50% with amino glycosides and ampicillin antibiotics at concentrations of 0.6 and
30 mg ml−1, respectively. This is the first report for the synthesis of cholesterol-conjugated magnetic nanoparticles for simple purification
of PON1 enzyme. 相似文献
2.
Eltayib Hassan Ahmed Tripti Raghavendra Datta Madamwar 《Applied biochemistry and biotechnology》2010,160(7):2102-2113
A mesophilic bacterial culture producing a novel thermostable alkaline lipase was isolated from oil rich soil sample and identified
as Bacillus subtilis EH 37. The lipase was partially purified by ammonium sulfate precipitation and hydrophobic interaction chromatography with
17.8-fold purification and 41.9 U/ml specific activity. The partially purified enzyme exhibited maximum activity at pH 8.0
and at 60 °C. It retained 100% of activity at 50 °C and 60 °C for 60 min. The presence of Ca+2, Mg+2, and Zn2+ exhibited stimulatory effect on lipase activity, whereas Fe+3 and Co+2 reduced its activity. The enzyme retained more than 80% of its initial activity upon exposure to organic solvents, exhibited
107% and 115% activity in the presence of 15% isopropyl alcohol and 30% n-hexane, respectively. The EH 37 lipase also proved
to be an efficient catalyst in synthesis of ethyl caprylate in organic solvent, thus providing a concept of application of
B. subtilis lipase in non-aqueous catalysis. 相似文献
3.
Purification and partial characterization of a lipase from Bacillus coagulans ZJU318 总被引:1,自引:0,他引:1
An extracellular lipase was purified from the fermentation broth of Bacillus coagulans ZJU318 by CM-Sepharose chromatography, followed by Sephacryl S-200 chromatography. The lipase was purified 14.7-fold with
18% recovery and a specific activity of 141.1 U/mg. The molecular weight of the homogeneous enzyme was (32 kDa), determined
by sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis. The enzyme activity was maximum at pH 9.0 and was stable
over a pH range of 7.0–10.0, and the optimum temperature for the enzyme reaction was 45°C. Little activity loss (6.2%) was
observed after 1 h of incubation at 40°C. However, the stability of the lipase decreased sharply at 50 and 60°C. The enzyme
activity was strongly inhibited by Ag+ and Cu2+, whereas EDTA caused no inhibition. SDS, Brij 30, and Tween-80 inhibited lipase, whereas Triton X-100 did not significantly
inhibit lipase activity. 相似文献
4.
Cyclodextrin glucanotransferase, produced by Bacillus megaterium, was characterized, and the biochemical properties of the purified enzyme were determined. The substrate specificity of the
enzyme was tested with different α-1,4-glucans. Cyclodextrin glucanotransferase displayed maximum activity in the case of
soluble starch, with a K
m value of 3.4 g/L. The optimal pH and temperature values for the cyclization reaction were 7.2 and 60 °C, respectively. The
enzyme was stable at pH 6.0–10.5 and 30 °C. The enzyme activity was activated by Sr2+, Mg2+, Co2+, Mn2+, and Cu2+, and it was inhibited by Zn2+and Ag+. The molecular mass of cyclodextrin glucanotransferase was established to be 73,400 Da by sodium dodecyl sulfate–polyacrylamide
gel electrophoresis, 68,200 Da by gel chromatography, and 75,000 Da by mass spectrometry. The monomer form of the enzyme was
confirmed by the analysis of the N-terminal amino acid sequence. Cyclodextrin glucanotransferase formed all three types of
cyclodextrins, but the predominant product was β-cyclodextrin. 相似文献
5.
A radiometric study of the kinetics of the displacement reaction between nickel(II) and65Zn-labeled zinc salt of ethylenediaminetetraacetic acid, which was previously used by the authors for the analysis of trace
quantities of nickel, has been carried out under varying conditions of temperature, pH etc. The above reaction was confirmed
to be first order with respect to both Ni2+ and to*ZnEDTA. The overall reaction rate constant, kf, has been shown to be inversely proportional to the concentration of Zn2+ and directly proportional to the concentration of H+. From the dependence of the rate constant on the concentration of Zn2+ and H+ a three-step mechanism is proposed for the above reaction. The values for Ea, ΔH‡, ΔG‡ and ΔS‡ for the overall reaction have been computed from the experimental data. 相似文献
6.
Qi Wu Chen Li Chenglei Li Hui Chen Liu Shuliang 《Applied biochemistry and biotechnology》2010,160(1):129-139
The collagenase, produced extracellular by Bacillus pumilus Col-J, was purified by ammonium sulfate precipitation followed by two gel filtrations, involving Sephadex G-100 column and
Sepharose Fast Flow column. Purified collagenase has a 31.53-fold increase in specific activity of 87.33 U/mg and 7.00% recovery.
The collagenase has a relative molecular weight of 58.64 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.
The optimal temperature for the enzyme reaction was 45 °C. More than 50% of the original activity still remained after 5 min
of incubation at 70 °C or 10 min at 60 °C. The maximal enzyme activity of collagenase was obtained at pH 7.5, and it was stable
over a pH range of 6.5–8.0. The collagenase activity was strongly inhibited by Mn2+, Pb2+, ethylenediamine tetraacetic acid, ethylene glycol tetraacetic acid, and β-mercaptoethanol. However, Ca2+ and Mg2+ greatly increased its activity. The collagenase from B. pumilus Col-J showed highly specific activity towards the native collagen from calf skin. The K
m and V
max of the enzyme for collagen were 0.79 mg/mL and 129.5 U, respectively. 相似文献
7.
Aminzadeh S Naderi-Manesh H Khajeh K Naderi-Manesh M 《Applied biochemistry and biotechnology》2006,135(3):193-208
For the first time, a polygalacturonase from the culture broth of Tetracoccosporium sp. was isolated and incubated at 30°C in an orbital shaker at 160 rpm for 48h. The enzyme was purified by ammonium sulfate
precipitation and two-step ion-exchange chromatography and had an apparent molecular mass of 36 kDa, as shown by sodium dodecyl
sulfate (SDS)-polyacrylamide gel electrophoresis. Its optimum activity was at pH 4.3 and 40°C, and the K
m
and V
max values of this enzyme (for polygalacturonic acid) were 3.23 mg/mL and 0.15 μmol/min, respectively. Ag+, Co2+, EDTA, Tween-20, Tween-80, and Triton X-100 stimulated polygalacturonase activity whereas Al3+, Ba2+, Ca2+, Fe2+, Fe3+, Ni2+, Mg2+, Mn2+, and SDS inhibited it. In addition, iodoacetamide and iodoacetic acid did not inhibit enzyme activity at a concentration
of 1 mM, indicating that cysteine residues are not part of the catalytic site of polygalacturonase. We studied the kinetic properties
and thermal inactivation of polygalacturonase. This enzyme exhibited a t
1/2 of 63 min at 60°C and its specific activity, turnover number, and catalytic efficiency were 6.17 U/mg, 113.64 min−1, and 35.18 mL/(min·mg), respectively. The activation energy (ΔE
#) for heat inactivation was 5.341 kJ/mol, and the thermodynamic activation parameters ΔG
#, ΔH
#, and ΔS
# were also calculated, revealing a potential application for the industry. 相似文献
8.
A thermostable cyclodextrinase (EC 3.2.1.54) fromBacillus stearothermophilus HY-1 was purified to homogeneity by disc-electrophoresis after sonication disruption, ammonium sulfate fractionation, DEAE-cellulose(DE32)
column chromatography, hydroxyapatite chromatography, Sephadex G150 gel-filtration, and α-cyclodextrin-AH-Sepharose 4B affinity
chromatography. The enzyme was purified 230-fold with 21.2% of activity recovery. The optimal substrates of the enzyme were
α-, Β-, and γ-cyclodextrins and linear maltooligosaccharides, and the final product was mainly maltose. The enzyme could hydrolyze
pullulan to produce panose. It could also hydrolyze soluble starch, amylose, and amylopectin, but not glycogen. The Km and
Vmax for α-, Β-, and γ-cyclodextrins were 1.79, 1.67, and 2.50 mg/mL, and 336, 185, and 208 Μmol/mg/min, respectively. The molecular
weight of the enzyme was 61,000 by SDS-gel-electrophoresis. The isoelectric point was pH 5.0. The enzyme was most active at
pH 6.2 and 55‡C, and it was strongly inhibited by Cu2+, Hg2+, Zn2+, Pb2+, and slightly by Fe2+. The effect of some protein modification reagents on the activity of the enzyme suggested that tryptophan and histidine residue(s)
may be located at the active site. The amino acid composition of the enzyme was also determined. 相似文献
9.
Maalej I Belhaj I Masmoudi NF Belghith H 《Applied biochemistry and biotechnology》2009,158(1):200-212
A thermostable xylanase from a newly isolated thermophilic fungus Talaromyces thermophilus was purified and characterized. The enzyme was purified to homogeneity by ammonium sulfate precipitation, diethylaminoethyl
cellulose anion exchange chromatography, P-100 gel filtration, and Mono Q chromatography with a 23-fold increase in specific
activity and 17.5% recovery. The molecular weight of the xylanase was estimated to be 25kDa by sodium dodecyl sulfate–polyacrylamide
gel electrophoresis and gel filtration. The enzyme was highly active over a wide range of pH from 4.0 to 10.0. The relative
activities at pH5.0, 9.0, and 10.0 were about 80%, 85.0%, and 60% of that at pH7.5, respectively. The optimum temperature
of the purified enzyme was 75°C. The enzyme showed high thermal stability at 50°C (7days) and the half-life of the xylanase
at 100°C was 60min. The enzyme was free from cellulase activity. K
m and V
max values at 50°C of the purified enzyme for birchwood xylan were 22.51mg/ml and 1.235μmol min−1 mg−1, respectively. The enzyme was activated by Ag+, Co2+, and Cu2+; on the other hand, Hg2+, Ba2+, and Mn2+ inhibited the enzyme. The present study is among the first works to examine and describe a secreted, cellulase-free, and
highly thermostable xylanase from the T. thermophilus fungus whose application as a pre-bleaching aid is of apparent importance for pulp and paper industries. 相似文献
10.
An extracellular thermostable α-galactosidase producing Aspergillus terreus
GR strain was isolated from soil sample using guar gum as sole source of carbon. It was purified to apparent homogeneity by
acetone precipitation, gel filtration followed by DEAE-Sephacel chromatographic step. The purified enzyme showed a single
band after sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The molecular weight of the purified enzyme
after SDS-PAGE was 108 kDa. The enzyme showed optimum pH and temperature of 5.0 and 65 °C, respectively, for artificial substrate
pNPαGal. α-Galactosidase from A. terreus
GR is found to be thermostable, as it was not inactivated after heating at 65 °C for 40 min. The K
m for pNPαGal, oNPαGal, raffinose, and stachyose are 0.1, 0.28, 0.42, and 0.33 mM, respectively. Inhibitors such as 1,10-phenanthroline,
phenylmethylsulfonyl fluoride, ethylenediaminetetraacetic acid, mercaptoethanol, and urea have no effect, whereas N-bromosuccinamide inhibited enzyme activity by 100%. Among metal ions tested, Mg2+, Ni2+, Ca2+, Co2+, and Mn2+ had no effect on enzyme activity, but Ag+, Hg2+, and Cu2+ have inhibited complete activity. 相似文献
11.
Shangfen Gao Guangqun Tan Hongyan Yuan Dan Xiao Martin M. F. Choi 《Mikrochimica acta》2006,153(3-4):159-162
A simple and green analytical procedure based on chlorophyll a is presented for the determination of Hg2+ ion. Chlorophyll a was extracted and purified from the leaves of pea and is employed as a reagent for analysis of Hg2+ ion. It displays remarkable fluorescence emission at 674 nm when excited at 412 nm. The emission intensity decreased significantly
on exposure to various concentrations of Hg2+ ion. This forms the basis for the determination of Hg2+ ion. The proposed method was evaluated for sensitivity and selectivity. The linear concentration range was found to be 2.0–10 μM
with r2 = 0.997 and the limit of detection for Hg2+ ion was 1.3 μM. Ions including Pb2+, Cd2+, Ag+, Zn2+, Co2+, Ni2+, Cu2+, Mg2+, Mn2+, Ru3+, Er3+, K+, Na+, NH4+, Cl−, NO3−, CH3COO− and SO42− did not interfere with the measurement of Hg2+ ion even at 500-fold excess. Since chlorophyll a is widely available in the leaves of most plants, and the extraction and purification process is simple, this technique can
provide an alternative, sensitive and economical way to determine Hg2+ ion. 相似文献
12.
Kouakou TH Dué EA Kouadio NE Niamké S Kouadio YJ Mérillon JM 《Applied biochemistry and biotechnology》2009,157(3):575-592
Two peroxidases, cPOD-I and rPOD-II, have been isolated and purified from cotton cell suspension and their biochemical characteristics
studied. rPOD-II from R405-2000, a non-embryogenic cultivar, has higher activity than cPOD-I derived from Coker 312, which
developed an embryogenic structure. The cPOD-I and rPOD-II had molecular mass of 39.1 and 64 kDa respectively, as determined
by SDS-PAGE. Both enzymes showed high efficiency of interaction with the guaiacol at 25 mM. The optimal pH for cPOD-I and
rPOD-II activity was 5.0 and 6.0, respectively. The enzyme had an optimum temperature of 25 °C and was relatively stable at
20–30 °C. The isoenzymes were highly inhibited by ascorbic acid, dithiothreitol, sodium metabisulfite, and β-mercaptoethanol.
Their activities were highly enhanced by Al3+, Fe3+, Ca2+, and Ni2+, but they were moderately inhibited by Mn2+ and K+. The enzyme lost 50% to 62% of its activity in the presence of Zn2+ and Hg2+. 相似文献
13.
Sasithorn Uttatree Pakorn Winayanuwattikun Jittima Charoenpanich 《Applied biochemistry and biotechnology》2010,162(5):1362-1376
The benzene tolerant Acinetobacter baylyi isolated from marine sludge in Angsila, Thailand could constitutively secrete lipolytic enzymes. The enzyme was successfully
purified 21.89-fold to homogeneity by ammonium sulfate precipitation and gel-permeable column chromatography with a relative
molecular mass as 30 kDa. The enzyme expressed maximum activity at 60°C and pH 8.0 with p-nitrophenyl palmitate as a substrate and found to be stable in pH and temperature ranging from 6.0-9.0 to 60-80°C, respectively.
A study on solvent stability revealed that the enzyme was highly resisted to many organic solvents especially benzene and
isoamyl alcohol, but 40% inhibited by decane, hexane, acetonitrile, and short-chain alcohols. Lipase activity was completely
inhibited in the presence of Fe2+, Mn2+, EDTA, SDS, and Triton X-100 while it was suffered detrimentally by Tween 80. The activity was enhanced by phenylmethylsulfonyl
fluoride (PMSF), Na+, and Mg2+ and no significant effect was found in the presence of Ca2+ and Li+. Half of an activity was retained by Ba2+, Ag+, Hg+, Ni2+, Zn2+, and DTT. The enzyme could hydrolyze a wide range of p-nitrophenyl esters, but preferentially medium length acyl chains (C8-C12). Among natural oils and fats, the enzyme 11-folds favorably catalyzed the hydrolysis of rice bran oil, corn oil, sesame
oil, and coconut oil in comparison to palm oil. Moreover, the transesterification activity of palm oil to fatty acid methyl
esters (FAMEs) revealed 31.64 ± 1.58% after 48 h. The characteristics of novel A. baylyi lipase, as high temperature stability, organic solvent tolerance, and transesterification capacity from palm oil to FAMEs,
indicate that it could be a vigorous biocatalyzer in the prospective fields as bioenergy industry or even in organic synthesis
and pharmaceutical industry. 相似文献
14.
The extracellular inulinase in the supernatant of the cell culture of the marine yeast Cryptococcus aureus G7a was purified to homogeneity with a 7.2-fold increase in specific inulinase activity compared to that in the supernatant
by ultrafiltration, concentration, gel filtration chromatography (Sephadex™ G-75), and anion exchange chromatography (DEAE
sepharose fast flow anion exchange). The molecular mass of the purified enzyme was estimated to be 60.0 kDa. The optimal pH
and temperature of the purified enzyme were 5.0 and 50 °C, respectively. The enzyme was activated by Ca2+, K+, Na+, Fe2+, and Zn2+. However, Mg2+, Hg2+, and Ag+ acted as inhibitors in decreasing the activity of the purified inulinase. The enzyme was strongly inhibited by phenylmethanesulphonyl
fluoride (PMSF), iodoacetic acid, EDTA, and 1,10-phenanthroline. The K
m and V
max values of the purified enzyme for inulin were 20.06 mg/ml and 0.0085 mg/min, respectively. A large amount of monosaccharides
were detected after the hydrolysis of inulin with the purified inulinase, indicating the purified inulinase had a high exoinulinase
activity. 相似文献
15.
A strain ofRhodococcus equi SHB-121 forming 3-cyanopyridine hydratase was screened from nitrile-polluted soil. The optimum conditions for the formation
of 3-cyanopyridine hydratase by the strain SHB-121 have been studied. Under the optimum conditions, the specific activity
of the enzyme reached 5.32 U/mg of dry cell, 95 times higher than that cultured in screening medium. In addition, the activity
of coexistent amidase was very low.
3-Cyanopyridine hydratase was purified from methylacrylamide-induced cells ofRh. equi SHB-121 by procedures including ultrasonic oscillation, ammonium sulfate precipitation, and column chromatographies on DEAE-cellulose
DE52, hydroxyapatite, and Sephadex G-25. The overall purification was 31-fold. The molecular weight of the enzyme was about
30 kDA by SDS-PAGE. The pI value was 4.1. The transition temperature and pH were 7.0°C and 6.0, respectively, resulting from
the differential spectra.
The optimum pH and temperature for the enzyme reaction were 8.0 and 30°C. The enzyme activity was strongly inhibited by Ag+, Hg2+, Cu2+, and NH4
+, whereas it was enhanced by Fe3+ slightly. The enzyme catalyzed the hydration of 3-cyanopyridine to nicotinamide, and itsKm value was 0.1 mol/L. Uncompetitive inhibitor sodium cyanide has a K, value of 5 mmol/L. 相似文献
16.
The purified α-amylase of Geobacillus thermoleovorans had a molecular mass of 26 kDa with a pI of 5.4, and it was optimally active at 100 °C and pH 8.0. The T
1/2 of α-amylase at 100 °C increased from 3.6 to 5.6 h in the presence of cholic acid. The activation energy and temperature
quotient (Q
10) of the enzyme were 84.10 kJ/mol and 1.31, respectively. The activity of the enzyme was enhanced strongly by Co2+ and Fe2+; enhanced slightly by Ba2+, Mn2+, Ni2+, and Mg2+; inhibited strongly by Sn2+, Hg2+, and Pb2+, and inhibited slightly by EDTA, phenyl methyl sulfonyl fluoride, N-ethylmaleimide, and dithiothreitol. The enzyme activity was not affected by Ca2+ and ethylene glycol-bis (β-amino ethyl ether)-N,N,N,N-tetra acetic acid. Among different additives and detergents, polyethylene glycol 8000 and Tween 20, 40, and 80 stabilized
the enzyme activity, whereas Triton X-100, glycerol, glycine, dextrin, and sodium dodecyl sulfate inhibited to a varied extent.
α-Amylase exhibited activity on several starch substrates and their derivatives. The K
m and K
cat values (soluble starch) were 1.10 mg/ml and 5.9 × 103 /min, respectively. The enzyme hydrolyzed raw starch of pearl millet (Pennisetum typhoides) efficiently. 相似文献
17.
Four myrosinase (β-thioglucosidase EC. 3.2.3.1) and seven disaccharase (β-fructofuranosidase, EC. 3.2.1.26) isoenzymes were isolated from turnip leaves. The most active enzymes were isolated in pure
form. Myrosinase and disaccharase mol wt was 62.0 × 103 and 69.5 × 103 dalton, respectively, on the basis of gel filtration on Sephadex G-200.
Myrosinase pH profile showed high activity between pH 5 and 7 with the optimum at pH 5.5. The purified enzyme was heat-stable
for 60 min at 30°C with only loss of 24% of activity. Its activity is strongly inhibited (100%) by Pb2+, Ba2+, Cu2+ and Ca2+ ions, and activated (70%) by EDTA at 0.04M. The pure enzyme failed to hydrolyze amylose, glycogen, lactose, maltose, and
sucrose. TheK
m andV
max values of myrosinase using sinigrin as specific substrate was 0.045 mM and 2.5 U, respectively.
The maximal activity of disaccharase enzyme was obtained at pH 4–5 and 35–37°C. The enzyme was heat-stable at 30°C for 30
min with only 10% loss of its activity. Its activity is strongly activated (70–240%) by Ca2+, Ba2+, Cu2+, and EDTA at 0.01M. The enzyme activity is specific to the disaccharide sucrose and failed to hydrolyze other disaccharides (maltose and lactose).
TheK
m andV
max of disaccharase were 0.123 mM and 3.33 U, respectively. 相似文献
18.
N. Mofaddel H. Krajian D. Villemin P. L. Desbène 《Analytical and bioanalytical chemistry》2009,393(5):1545-1554
The potentialities of new ionic liquids (ILs) based on choline were evaluated as an electrophoretic medium in capillary electrophoresis
for the analysis of alkaline and alkaline earth cations (Li+, K+, Na+, Cs+, Mg2+, Ba2+, Ca2+, and Sr2+) with indirect UV detection. Two types of capillaries were tested: an untreated fused silica and fused silica coated with
a film of polyvinylalcohol. The coated capillary proved to be the best adapted for the metal ions studied. Moreover, it appeared
that the nature of the ionic liquid anion influenced the baseline stability, and the bis(trifluoromethylsulfonyl) imide (NTf2
−) anion seemed to be the most efficient. These preliminary studies led us to synthesize a new ionic liquid, 2-hydroxy-N,N,N-trimethyl-1-phenylethanaminium NTf2 (phenylcholine NTf2). This liquid was able to act as the running electrolyte and probe, generating the background signal in indirect UV light
and consequently simplifying the electrophoretic medium. Excellent baseline stability, good reproducibility, as well as good
sensitivity of detection were obtained with this new ionic liquid. Thus, 510,000 plates/meter for Li+ with 40 mM IL were successfully obtained. The optimal concentration of IL was 20 mM with a detection limit ranging from 28 μg
L−1 for Li+ to 1,000 μg L−1 for Cs+. This method (phenylcholine NTf2 with polyvinylalcohol capillary) was applied to analyze different commercial source and mineral waters. Finally, the potentiality
of this ionic liquid in nonaqueous capillary electrophoresis was explored. The use of phenylcholine NTf2 with a fused silica capillary, in pure methanol medium and in the presence of acetic acid, made it possible to obtain separation
selectivity different from that obtained in aqueous medium. 相似文献
19.
Jaya Ram Simkhada Seung Sik Cho Seong Ju Park Poonam Mander Yun Hee Choi Hyo Jeong Lee Jin Cheol Yoo 《Applied biochemistry and biotechnology》2010,162(5):1457-1470
Organic solvent- and detergent-resistant proteases are important from an industrial viewpoint. However, they have been less
frequently reported and only few of them are from actinomycetes. A metalloprotease from Streptomyces olivochromogenes (SOMP) was purified by ion exchange with Poros HQ and gel filtration with Sepharose CL-6B. Apparent molecular mass of the
enzyme was estimated to be 51 kDa by sodium dodecyl sulfate–polyacrylamide gel electrophoresis and gelatin zymography. The
activity was optimum at pH 7.5 and 50 °C and stable between pH 7.0 and 10.0. SOMP was stable below 45 °C and Ca2+ increased its thermostability. Ca2+ enhanced while Co2+, Cu2+, Zn2+, Mn2+, and Fe2+ inhibited the activity. Ethylenediaminetetraacetic acid and ethylene glycol-bis (β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid, but not phenylmethylsulfonyl fluoride, aprotinin, and pefabloc SC, significantly suppressed the activity,
suggesting that it might be a metalloprotease. Importantly, it is highly resistant against various detergents, organic solvents,
and oxidizing agents, and the activity is enhanced by H2O2. The enzyme could be a novel protease based on its origin and peculiar biochemical properties. It may be useful in biotechnological
applications especially for organic solvent-based enzymatic synthesis. 相似文献
20.
Jeong Hee Moon So Hee Yoon Yong Jin Bae Myung Soo Kim 《Journal of the American Society for Mass Spectrometry》2010,21(7):1151-1158
The yields of post-source decay (PSD) and time-resolved photodissociation (PD) at 193 and 266 nm were measured for singly
protonated leucine enkephalin ([YGGFL + H]+), a benchmark in the study of peptide ion dissociation, by using tandem time-of-flight mass spectrometry. The peptide ion
was generated by matrix-assisted laser desorption ionization (MALDI) using 2,5-dihydroxybenzoic acid as the matrix. The critical
energy (E0) and entropy (ΔS‡ at 1000 K) for the dissociation were determined by Rice-Ramsperger-Kassel-Marcus fit of the experimental
data. MALDI was done for a mixture of YGGFL and Y6 and the plume temperature determined by the kinetic analysis of [Y6 + H]+ data were used to improve the precision of E0 and ΔS‡ for [YGGFL + H]+. E0 and ΔS‡ thus determined (E0 = 0.67 ± 0.08 eV, ΔS‡=−24.4 ± 3.2 eu with 1 eu = 4.184 J K−1mol−1) were significantly different from those determined by blackbody infrared radiative dissociation (BIRD) (E0 = 1.10 eV, ΔS‡ = −14.9 eu), and by surface-induced dissociation (SID) (E0 = 1.13 eV, ΔS‡ = −10.3 eu). Analysis of the present experimental data with the SID kinetics (and BIRD kinetics also) led
to an unrealistic situation where not only PSD and PD but also MALDI-TOF signals could not be detected. As an explanation
for the discrepancy, it was suggested that transition-state switching occurs from an energy bottleneck (SID/BIRD) to an entropy
bottleneck (PSD/PD) as the internal energy increases. 相似文献