共查询到20条相似文献,搜索用时 15 毫秒
1.
Ying Peng Zhen-Ming Chi Xiang-Hong Wang Jing Li 《Applied microbiology and biotechnology》2009,85(1):85-94
The extracellular β-1,3-glucanases in the supernatant of cell culture of the marine yeast Williopsis saturnus WC91-2 was purified to homogeneity with a 115-fold increase in specific β-1,3-glucanase activity as compared to that in the
supernatant by ultrafiltration, gel filtration chromatography, and anion-exchange chromatography. According to the data from
sodium dodecyl sulfate polyacrylamide gel electrophoresis, the molecular mass of the purified enzyme was estimated to be 47.5 kDa.
The purified enzyme could convert laminarin into monosaccharides and disaccharides, but had no killer toxin activity. The
optimal pH and temperature of the purified enzyme were 4.0 and 40°C, respectively. The enzyme was significantly stimulated
by Li+, Ni2+, and Ba2+. The enzyme was inhibited by phenylmethylsulfonyl fluoride, iodoacetic acid, ethylenediamine tetraacetic acid, ethylene glycol
bis(2-aminoethyl ether)-N,N,N′,N′-tetraacetic acid, and 1,10-phenanthroline. The K
m and V
max values of the purified enzyme for laminarin were 3.07 mg/ml and 4.02 mg/min ml, respectively. Both matrix-assisted laser
desorption/ionization time-of-flight/time-of-flight mass spectroscopy and DNA sequencing identified a peptide YIEAQLDAFEKR
which is the conserved motif of the β-1,3-glucanases from other yeasts. 相似文献
2.
The recombinant β-carotene 15,15′-monooxygenase from chicken liver was purified as a single 60 kDa band by His-Trap HP and Resource Q chromatography.
It had a molecular mass of 240 kDa by gel filtration indicating the native form to be tetramer. The enzyme converted β-carotene under maximal conditions (pH 8.0 and 37°C) with a k
cat of 1.65 min−1 and a K
m of 26 μM and its conversion yield of β-carotene to retinal was 120% (mol mol−1). The enzyme displayed catalytic efficiency and conversion yield for β-carotene, β-cryptoxanthin, β-apo-8′-carotenal, β-apo-4′-carotenal, α-carotene and γ-carotene in decreasing order but not for zeaxanthin, lutein, β-apo-12′-carotenal and lycopene, suggesting that the presence of one unsubstituted β-ionone ring in a substrate with a molecular weight greater than C30 seems to be essential for enzyme activity. 相似文献
3.
The enzyme adenosine 5′-monophosphate deaminase (AMPD, EC 3.5.4.6) catalyzes the conversion of adenosine 5′-monophosphate
to inosine 5′-mononucleotide (IMP). IMP is generally known as the compound responsible for the umami taste of the edible red alga Porphyra yezoensis Ueda that is known in Japan as nori. Therefore, we suspect that AMPD plays a key role in providing a favorable nori taste. In this study, we undertake the molecular
characterization of nori-derived AMPD. The nori AMPD protein has a molecular mass of 55 kDa as estimated from both gel filtration
and sodium dodecyl sulfate polyacrylamide gel electrophoresis. The calculated molecular mass from the amino acid sequence
deduced from cDNA is 57.1 kDa. The isoelectric point is 5.71. The coding region of AMPD consists of 1,566 bp encoding 522 amino acids and possesses a transmembrane domain and two N-glycosylation sites. The sequence identity of nori AMPD in human and yeast AMPDs was found to be less than 50% and 20% in
DNA and amino acid sequences, respectively. Proline in the conserved motif of [SA]-[LIVM]-[NGS]-[STA]-D-D-P was found to be
converted to glutamate. These results indicate that nori AMPD is a novel type of AMPD. 相似文献
4.
The endopolysaccharide accumulated by Thermococcus hydrothermalis was extracted and purified from a 4 h culture. It presented an “amylopectin-like” structure with an average chain length
of 14 and a ramification degree of 7.5%. The glucosyltransferase was isolated, partially purified and characterized. The molecular
mass was 42 kDa by SDS PAGE and 85 ± 5 kDa by gel filtration. This enzyme was able to use both Uridine-5′-DiPhosphoGlucose
(UDPG) and Adenosine-5′-DiPhosphoGlucose (ADPG) as substrates. Optimal pH and temperature for the enzyme were 5.5 and 80°C,
respectively. In the presence of 3.2 mM ADPG, the half life of the protein was 6 min at 110°C. The apparent K
m
value with the two substrates was 0.9 mM, but the V
max
was 9.7 fold higher for ADPG. A branching activity was also detected at high temperature, up to 80°C by different methods:
phosphorylase stimulation, iodine, and branching linkage assays. 相似文献
5.
Manish Kumar Tiwari Hee-Jung Moon Marimuthu Jeya Jung-Kul Lee 《Applied microbiology and biotechnology》2010,87(2):571-581
An NAD+-dependent xylitol dehydrogenase from Rhizobium etli CFN42 (ReXDH) was cloned and overexpressed in Escherichia coli. The DNA sequence analysis revealed an open reading frame of 1,044 bp, capable of encoding a polypeptide of 347 amino acid
residues with a calculated molecular mass of 35,858 Da. The ReXDH protein was purified as an active soluble form using GST
affinity chromatography. The molecular mass of the purified enzyme was estimated to be ∼34 kDa by sodium dodecyl sulfate–polyacrylamide
gel and ∼135 kDa with gel filtration chromatography, suggesting that the enzyme is a homotetramer. Among various polyols,
xylitol was the preferred substrate of ReXDH with a K
m = 17.9 mM and kcat
/K
m = 0.5 mM−1 s−1 for xylitol. The enzyme had an optimal pH and temperature of 9.5 and 70 °C, respectively. Heat inactivation studies revealed
a half life of the ReXDH at 40 °C of 120 min and a half denaturation temperature (T
1/2) of 53.1 °C. ReXDH showed the highest optimum temperature and thermal stability among the known XDHs. Homology modeling and
sequence analysis of ReXDH shed light on the factors contributing to the high thermostability of ReXDH. Although XDHs have
been characterized from several other sources, ReXDH is distinguished from other XDHs by its high thermostability. 相似文献
6.
Purification and properties of betaine aldehyde dehydrogenase from<Emphasis Type="Italic"> Avena sativa</Emphasis> 总被引:3,自引:0,他引:3
Livingstone JR Maruo T Yoshida I Tarui Y Hirooka K Yamamoto Y Tsutui N Hirasawa E 《Journal of plant research》2003,116(2):133-140
Betaine aldehyde dehydrogenase (BADH; EC 1.2.1.8) is the enzyme that catalyzes the second step in the synthesis of the osmoprotectant,
glycine betaine. NAD-dependent BADH was purified from Avena sativa shoots by DEAE Sephacel, hydroxyapatite, 5′-AMP Sepharose 4B, Mono Q and TSK-GEL column chromatographies to homogeneity by
the criterion of native PAGE, and the properties of BADH were compared with those of aminoaldehyde dehydrogenase purified
to homogeneity from A. sativa. The molecular mass estimated by both gel filtration using TSK-GEL column and Sephacryl S-200 was 120 and 115, kDa, respectively.
The enzyme is a homodimer with a subunit molecular mass of 61 kDa as shown by SDS-PAGE. The pI value of the enzyme was found
to be 6.3. The purified enzyme catalyzed not only the oxidation of betaine aldehyde (BAL), but also that of aminoaldehydes,
3-aminopropionaldehyde (APAL), 4-aminobutyraldehyde (ABAL), and 4-guanidinobutyraldehyde (GBAL). The K
m values for BAL, APAL, ABAL and GBAL were 5×10−6, 5.4×10−7, 2.4×10−5 and 5×10−5 M, respectively. APAL showed substrate inhibition at a concentration of 0.1 mM. A fragment of BADH cleaved by V8 protease
shared homology with other plant BADHs.
Electronic Publication 相似文献
7.
Iwasaki A Matsumoto K Hasegawa J Yasohara Y 《Applied microbiology and biotechnology》2012,93(4):1563-1573
A novel (R)-amine transaminase, which catalyzed (R)-enantioselective transamination of chiral amine, was purified to homogeneity from Arthrobacter sp. KNK168 (FERM BP-5228). The molecular mass of the enzyme was estimated to be 148 kDa by gel filtration and 37 kDa by sodium
dodecyl sulfate polyacrylamide gel electrophoresis, suggesting a homotetrameric structure. The enzyme catalyzed transamination
between amines and pyruvate stereo-specifically. The reaction on 1-methylbenzylamine was (R)-enantioselective. Pyruvate was the best amino acceptor, but the enzyme showed broad amino acceptor specificity for various
ketone and aldehyde compounds. The apparent K
ms for (R)-1-methylbenzylamine and pyruvate were 2.62 and 2.29 mM, respectively. The cloned gene of the enzyme consists of an open
reading frame (ORF) of 993 bp encoding a protein of 330 amino acids, with a calculated molecular weight of 36,288. The deduced
amino acid sequence was found to be homologous to those of the aminotransferases belonging to fold class IV of pyridoxal-5′-phosphate-dependent
enzymes, such as branched-chain amino acid aminotransferases. 相似文献
8.
N. Sridevi Sameer Srivastava Bashir Mohammad Khan Asmita Ashutosh Prabhune 《Extremophiles : life under extreme conditions》2009,13(2):363-370
A thermophilic microorganism producing bile salt hydrolase was isolated from hot water springs, Pali, Maharashtra, India.
This microorganism was identified as Brevibacillus sp. by 16S rDNA sequencing. Bile salt hydrolase (BSH) was purified to homogeneity from this thermophilic source using Q-sepharose
chromatography and its enzymatic properties were characterized. The subunit molecular mass of the purified enzyme was estimated
to be 28 kDa by SDS-PAGE and, 28.2 kDa by MALDI-TOF analysis. The native molecular mass was estimated to be 56 kDa by gel
filtration chromatography, indicating the protein to be a homodimer. The pH and temperature optimum for the enzyme catalysis
were 9.0 and 60°C, respectively. Even though BSH from Brevibacillus sp. hydrolyzed all of the six major human bile salts, the enzyme preferred glycine conjugated substrates with apparent K
M and k
cat values of 3.08 μM and 6.32 × 102 s−1, respectively, for glycodeoxycholic acid. The NH2-terminal sequence of the purified enzyme was determined and it did not show any homology with other bacterial bile salt hydrolases.
To our knowledge, this is the first report describing the purification of BSH to homogeneity from a thermophilic source.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
9.
Myeong Min Lee Kyoung Hee Nam Eun Kyoung Lee Sun Hi Lee Ky Young Park 《Journal of Plant Biology》1997,40(2):80-88
We have partially purified S-adenosylmethionine decarboxylase (EC 4.1.1.50, SAMDC) from carnation (Dianthus caryophyllus L.) petals and generated polyclonal antibodies against CSDC 16 protein (Leeet al., 1996) overexpressed inE. coli. The protein has been purified approximately 126.8 fold through the steps involving ammonium sulfate fractionation, DEAE-Sepharose
column chromatography and Sephacryl S-300 gel filtration. Its molecular mass was 42 kDa in native form and we could also detect
a band of 32 kDa molecular mass on SDS-PAGE in western blot analysis using the polyclonal antibodies. The Km value of this
enzyme forS-adenosylmethionine was 26.3 μM. The optimum temperature and pH forS-adenosylmethionine decarboxylase activity were 35°C and pH 8.0, respectively. Putrescine and Mg2+ had no effects on the activation of the enzyme activity. Mg2+ did not have any significant effects on the enzyme activity. SAMDC activity was inhibited by putrescine, spermidine and spermine.
Methylglyoxal bis-(guanylhydrazone) (MGBG), carbonyl reagents such as hydroxylamine and phenylhydrazine, and sulfhydryl reagent
such as 5,5′dithio-bis (2-nitrobenzoic acid) (DTNB) were effective inhibitors of the enzyme. However, isonicotinic acid hydrazide
known as an inhibitor of 5′-pyridoxal phosphate (PLP) dependent enzyme activity had no significant effect on the enzyme activity.
These results and our previously reported results (Leeet al., 1997b) suggest thatS-adenosylmethionine decarboxylase is a heterodimer, αβ, and some carbonyl group and sulfhydryl group are involved in the catalytic
activity. 相似文献
10.
Margaret M. Attwood Nico Arfman Ruud A. Weusthuis Lubbert Dijkhuizen 《Antonie van Leeuwenhoek》1992,62(3):201-207
WhenArthrobacter P1 is grown on choline, betaine, dimethylglycine or sarcosine, an NAD+-dependent formaldehyde dehydrogenase is induced. This formaldehyde dehydrogenase has been purified using ammonium sulphate fractionation, anion exchange- and hydrophobic interaction chromatography. The molecular mass of the native enzyme was 115 kDa±10 kDa. Gel electrophoresis in the presence of sodium dodecyl sulphate indicated that the molecular mass of the subunit was 56 kDa±3 kDa, which is consistent with a dimeric enzyme structure. After ammonium sulphate fractionation the partially purified enzyme required the addition of a reducing reagent in the assay mixture for maximum activity. The enzyme was highly specific for its substrates and the Km values were 0.10 and 0.80 mM for formaldehyde and NAD+, respectively. The enzyme was heat-stable at 50° C for at least 10 min and showed a broad pH optimum of 8.1 to 8.5. The addition of some metal-binding compounds and thiol reagents inhibited the enzyme activity.Abbreviation RuMP
Ribulose monophosphate 相似文献
11.
An extracellular endo-d-arabinase enzyme produced by the bacterial strain of Cellulomonas was purified 77.1-fold with 0.20% recovery for protein by DEAE Sepharose anion exchange, Sephacryl S-300 gel filtration and
blue Sepharose affinity chromatography, and designated as CEDAase. The apparent molecular mass of CEDAase was 45 kDa determined
by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. CEDAase is an endoenzyme for arabinogalactan with the main and
specific product of hexa-arabinofuranoside. It reacts optimally with its substrate, arabinogalactan, at approximately pH 8.0
and at 40 °C. CEDAase shows stability in the pH range of 6.0–9.0 and at the temperature below 50 °C. The Km measured for the CEDAase was 55.6 μM, with an apparent Vmax of 0.083 μmol/min. To our knowledge, for the first time, the current work obtains an extracellular Cellulomonas endo-d-arabinase enzyme that might be potentially served as a tool enzyme for hydrolyzing specific cell wall such as Mycobacterium cell. It is purified as an important potential initial material basis for mass spectrometric sequencing and chemical gene
synthesis. It may make it possible to clone and express this valuable endo-d-arabinase and make it available to the mycobacteria scientific community. 相似文献
12.
Aspartate transcarbamoylase (ATCase) was purified from Streptomyces griseus. The enzyme is a dodecamer with a molecular mass of approximately 450 kDa. The holoenzyme is a complex of ATCase and active
dihydroorotase (DHOase) subunits. The ATCase and DHOase activities co-purify after gel filtration and ion-exchange chromatography.
Denaturing gel electrophoresis separates the holoenzyme into a 38-kDa ATCase polypeptide and a 47-kDa DHOase polypeptide.
The holoenzyme retained ATCase and DHOase activity after being heated to 65°C for 5 min, but after storage at 4°C for 24 hours
lost ATCase activity. Previously, the Pseudomonas putida Class A ATCase was defined by Schurr et al. (J Bacteriol 177, 1751–1759) as requiring an inactive DHOase to be functional.
Here, we show that an active DHOase is part of the dodecameric ATCase/DHOase complex in Streptomyces. To distinguish those Class A ATCases with active DHOases from those with degenerate DHOases, we suggest the subdivision,
Class A1, for the former and Class A2 for the latter.
Received: 23 December 1998 / Accepted: 4 June 1999 相似文献
13.
Lu L Zhao M Zhang BB Yu SY Bian XJ Wang W Wang Y 《Applied microbiology and biotechnology》2007,74(6):1232-1239
The white rot fungus Pycnoporus sanguineus produced high amount of laccase in the basal liquid medium without induction. Laccase was purified using ultrafiltration,
anion-exchange chromatography, and gel filtration. The molecular weight of the purified laccase was estimated as 61.4 kDa
by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme oxidized typical substrates of laccases including
2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonate), 2,6-dimethoxyphenol, and syringaldazine. The optimum pH and temperature for the purified
laccase were 3.0 and 65°C, respectively. The enzyme was stable up to 40°C, and high laccase activity was maintained at pH 2.0–5.0.
Sodium azide, l-cysteine, and dithiothreitol strongly inhibited the laccase activity. The purified enzyme efficiently decolorized Remazol
Brilliant Blue R in the absence of added redox mediators. The high production of P. sanguineus laccase as well as its decolorization ability demonstrated its potential applications in dye decolorization. 相似文献
14.
Haruhito Tsuge Kenji Ozeki Kazuji Ohashi 《Bioscience, biotechnology, and biochemistry》2013,77(10):2329-2335
Pyridoxamine (pyridoxine) 5′-phosphate oxidase purified from baker’s yeast was found to have a molecular weight of ca, 55,000 daltons based on polyacrylamide gel electrophoresis. The size of the enzyme subunit was analyzed by gel electrophoresis in the presence of sodium dodecylsulfate. This showed that the enzyme was composed of two nonidentical subunits with a molecular weight of 27,000 and 25,000 daltons. Fluorescence titration of the apoenzyme with FMN suggested that the holoenzyme contained one mol of FMN per mol of the enzyme. The Km value of FMN for apoenzyme was calculated to be ca. 16 nm on both activities of pyridoxamine 5′-phosphate oxidase and pyridoxine 5′-phosphate oxidase. 相似文献
15.
A C S Rizzatti J A Jorge H F Terenzi C G V Rechia M L T M Polizeli 《Journal of industrial microbiology & biotechnology》2001,26(3):156-160
A β-D-xylosidase was purified from cultures of a thermotolerant strain of Aspergillus phoenicis grown on xylan at 45°C. The enzyme was purified to homogeneity by chromatography on DEAE-cellulose and Sephadex G-100. The
purified enzyme was a monomer of molecular mass 132 kDa by gel filtration and SDS-PAGE. Treatment with endoglycosidase H resulted
in a protein with a molecular mass of 104 kDa. The enzyme was a glycoprotein with 43.5% carbohydrate content and exhibited
a pI of 3.7. Optima of temperature and pH were 75°C and 4.0–4.5, respectively. The activity was stable at 60°C and had a K
m of 2.36 mM for p-nitrophenyl-β-D-xylopiranoside. The enzyme did not exhibit xylanase, cellulase, galactosidase or arabinosidase activities. The purified enzyme
was active against natural substrates, such as xylobiose and xylotriose. Journal of Industrial Microbiology & Biotechnology (2001) 26, 156–160.
Received 23 June 2000/ Accepted in revised form 29 September 2000 相似文献
16.
Tomofumi Okuno Shin Ji Motobayashi Hitoshi Ueno Katsuhiko Nakamuro 《Biological trace element research》2005,106(1):77-93
The objective of this study was to purify and characterize a mouse hepatic enzyme that directly generates CH3SeH from seleno-l-methionine (l-SeMet) by the α,γ-elimination reaction. The l-SeMet α,γ-elimination enzyme was ubiquitous in tissues from ICR mice and the activity was relatively high in the large intestine,
brain, and muscle, as well as the liver. Aging and sex of the mice did not have any significant influence on the activity
in the liver. The enzyme was purified from the mouse liver by ammonium sulfate precipitation and four kinds of column chromatography.
These procedures yielded a homogeneous enzyme, which was purified approx 1000-fold relative to mouse liver extract. Overall
recovery was approx 8%. The purified enzyme had a molecular mass of approx 160 kDa with four identical subunits. The K
m
value of the enzyme for the catalysis of l-SeMet was 15.5 m M, and the V
max was 0.29 units/mg protein. Pyridoxal 5′-phosphate (pyridoxal-P) was required as a cofactor because the holoenzyme could be
resolved to the apoenzyme by incubation with hydroxylamine and reconstituted by addition of pyridoxal-P. The enzyme showed
the optimum activity at around pH 8.0 and the highest activity at 50°C; it catalyzed the α,γ-elimination reactions of several
analogs such as d,l-homocysteine and l-homoserine in addition to l-SeMet. This enzyme also catalyzed the α,β-elimination reaction of Se-methylseleno-l-cysteine. However, l-methionine was inerts. Therefore, the purified enzyme was different from the bacterial l-methionine γ-lyase that metabolizes l-SeMet to CH3SeH, in terms of the substrate specificity. These results were the first identification of a mammalian enzyme that specifically
catalyzes the α,γ-elimination reaction of l-SeMet and immediately converts it to CH3SeH, an important metabolite of Se. 相似文献
17.
The high level expression and purification of rat monoamine oxidase B (rMAOB) in the methylotrophic yeast Pichia pastoris is reported. Nearly 100 mg of purified rMAOB is obtained from 130 g (wet weight) of cells (0.5 L of culture). The MALDI-TOF mass spectrum of the purified protein shows a single species with a molecular mass of 59.228 ± 0.064 kDa, which agrees with the calculated molecular weight of 59.172 kDa for the rMAOB protein sequence assuming one mole of covalent FAD per mole of the enzyme. Consistent with the MALDI-MS data, purified rMAOB shows a single band near 60 kDa in Coomassie-stained SDS–PAGE gel as well as on Western blot analyses performed using antisera raised against human MAOA and BSA-conjugated FAD. A partial amino acid sequence of the purified protein is confirmed to be that of the wild type rMAOB by in-gel trypsin digestion and MALDI-TOF-MS analyses of the liberated peptide fragments. Steady state kinetic data show that purified rMAOB exhibits a Km(amine) of 176 ± 15 μM and a kcat of 497 ± 83 min−1 for benzylamine oxidation, and a Km(O2) of 170 ± 10 μM. Kinetic parameters obtained for purified rMAOB are compared with those reported earlier for recombinant human liver MAOB expressed in P. pastoris. 相似文献
18.
Mao Ye Gang Li Wei Qu Liang Yu Huan Liu 《Applied microbiology and biotechnology》2010,87(3):1023-1031
Lac591, a gene encoding a novel multicopper oxidase with laccase activity, was identified through activity-based functional screening
of a metagenomic library from mangrove soil. Sequence analysis revealed that lac591 encodes a protein of 500 amino acids with a predicted molecular mass of 57.4 kDa. Lac591 was overexpressed heterologously
as soluble active enzyme in Escherichia coli and purified, giving rise to 380 mg of purified enzyme from 1 l induced culture, which is the highest expression report for
bacterial laccase genes so far. Furthermore, the recombinant enzyme demonstrated activity toward classical laccase substrates
syringaldazine (SGZ), guaiacol, and 2, 6-dimethoxyphenol (2, 6-DMP). The purified Lac591 exhibited maximal activity at 55°C
and pH 7.5 with guaiacol as substrate and was found to be stable in the pH range of 7.0–10.0. The substrate specificity on
different substrates was studied with the purified enzyme, and the optimal substrates were in the order of 2, 6-DMP > catechol
> α-naphthol > guaiacol > SGZ > 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid). The alkaline activity and highly soluble
expression of Lac591 make it a good candidate of laccases in industrial applications for which classical laccases are unsuitable,
such as biobleaching of paper pulp and dyestuffs processing. 相似文献
19.
Mohammad Shafiei Abed-Ali Ziaee Mohammad Ali Amoozegar 《Journal of industrial microbiology & biotechnology》2011,38(2):275-281
A halophilic α-amylase produced by Nesterenkonia sp. strain F was purified to homogeneity by 80% ethanol precipitation, Q-Sepharose anion exchange, and Sephacryl S-200 gel
filtration chromatography. The purified amylase exhibited specific activity of 357 unit/mg protein that corresponds to twofold
purification. The molecular mass of the amylase was determined to be 57 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis
(SDS-PAGE) and gel filtration chromatography. The optimal pH and temperature for enzyme activity were 6.5 and 45°C, respectively.
The amylase was active over a wide range of salt concentrations (0–4 M) with maximum activity at 0.75–1 M NaCl. The α-amylase
activity was stimulated by Ca2+ and inhibited by ethylenediamine tetraacetic acid (EDTA), suggesting that this enzyme is a metalloenzyme. The purified enzyme
showed remarkable stability towards surfactants (Tween 20, Tween 80, and Triton X-100), and its activity was increased by
β-mercaptoethanol. The halophilic α-amylase was stable in the presence of various organic solvents such as benzene, chloroform,
toluene, and cyclohexane. These properties indicate wide potential applications of this α-amylase in starch-processing industries. 相似文献
20.
Balabanova LA Gafurov YM Pivkin MV Terentyeva NA Likhatskaya GN Rasskazov VA 《Marine biotechnology (New York, N.Y.)》2012,14(1):87-95
An extracellular nuclease was purified 165-fold with a specific activity of 41,250 U/mg poly(U) by chromatography with modified
chitosan from the culture of marine fungus Penicillium melinii isolated from colonial ascidium collected near Shikotan Island, Sea of Okhotsk, at a depth of 123 m. The purified nuclease
is a monomer with the molecular weight of 35 kDa. The enzyme exhibits maximum activity at pH 3.7 for DNA and RNA. The enzyme
is stable until 75°C and in the pH range of 2.5–8.0. The enzyme endonucleolytically degrades ssDNA and RNA by 3′–5′ mode to
produce 5′-oligonucleotides and 5′-mononucleotides; however, it preferentially degrades poly(U). The enzyme can digest dsDNA
in the presence of pregnancy-specific beta-1-glycoprotein-1. The nuclease acts on closed circular double-stranded DNA to produce
opened circular DNA and then the linear form DNA by single-strand scission. DNA sequence encoding the marine fungus P. melinii endonuclease revealed homology to S1-type nucleases. The tight correlation found between the extracellular endonuclease activity
and the rate of H3-thymidine uptake by actively growing P. melinii cells suggests that this nuclease is required for fulfilling the nucleotide pool of precursors of DNA biosynthesis during
the transformation of hyphae into the aerial mycelium and conidia in stressful environmental conditions. 相似文献