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1.
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
2.
3.
The protective antigen (PA) of Bacillus anthracis is a potent immunogen and an important candidate vaccine. In addition, it is used in monitoring systems like enzyme-linked
immunosorbent assay to assess antibodies against PA in immunized subjects. The low level of PA production in B. anthracis and the difficulty of separating it from other bacterial components have made the researchers do different studies with the
aim of producing recombinant PA (rPA). In this study, to produce rPA as a recombinant protein vaccine, the partial sequence
of protective antigen of B. anthracis, amino acids 175–764, as a potent immunogenic target was inserted in pET21b(+). This is a prokaryotic plasmid that carries
an N-terminal T7.tag sequence. The integrity of constructed plasmid was confirmed using restriction enzyme mapping. rPA was
expressed after induction with isopropyl β-d-1-thiogalactopyranoside in Escherichia coli BL21. Purification of rPA was done with an affinity system using anti T7.tag antibody. Electrophoresis and Western blotting
confirmed the specificity of the expressed protein. BALB/c mice were immunized with obtained PA protein and evaluation of
specific immunoglobulin G antibodies against PA in sera using Western blotting method and showed that rPA is immunogenic.
The challenge of immunized mice with virulent strain of B. anthracis showed that rPA is functional to protect against pathogenic strain. 相似文献
4.
Gilbert Michel Breuil Colette Yaguchi Makoto Saddler J. N. 《Applied biochemistry and biotechnology》1992,(1):247-259
Thielavia terrestris 255B, a thermophilic ascomycete, produced two major forms of xylanase with pIs of 4.6 (xylanase I) and 6.1 (xylanase II).
The latter enzyme could be purified to > 99% homogeneity using anion-exchange chromatography and gel filtration. Xylanase
II had a mol wt of 25.7 kDa (SDS-PAGE) and a pH and a temperature optimum of 3.6–4.0 and 60–65°C, respectively. The ratio
of the enzyme’s activity against xylan and carboxymethylcellulose was 500–1000 to 1, indicating a possible application of
this enzyme in biobleaching processes. The amino acid sequence of this protein is being determined, and initial data suggest
that the enzyme belongs to a group of low-mol wt xylanases that have been isolated from both bacteria and fungi. 相似文献
5.
Summary. Secreted peptides from diverse sources have been found to contain a d-amino acid. From the sequence of cloned mRNAs coding for the precursors of such peptides it could be deduced that in all cases tested so far the d-amino acid in the final product is derived from the corresponding l-amino acid present in the primary product of translation. Enzymes catalyzing such an l- to d-isomerization in peptide linkage have been isolated from the venom of a spider and the skin secretions of frogs. Even though
these are completely different proteins, the reaction mechanism is the same, namely a de-protonation/re-protonation of the
α-carbon of an amino acid with concomitant inversion of the chirality. Sequences potentially coding for homologues of the
frog enzyme are present in the genome of different vertebrate species. 相似文献
6.
Folding dynamics and energy landscape picture of protein conformations of HP-36 andβ-amyloid (Aβ) are investigated by extensive Brownian dynamics simulations, where the inter amino acid interactions are given by a minimalistic
model (MM) we recently introduced [J. Chem. Phys.
118 4733 (2003)]. In this model, a protein is constructed by taking two atoms for each amino acid. One atom represents the backbone
Cαs atom, while the other mimics the whole side chain residue. Sizes and interactions of the side residues are all different
and specific to a particular amino acid. The effect of water-mediated folding is mapped into the MM by suitable choice of
interaction parameters of the side residues obtained from the amino acid hydropathy scale. A new non-local helix potential
is incorporated to generate helices at the appropriate positions in a protein. Simulations have been done by equilibrating
the protein at high temperature followed by a sudden quench. The subsequent folding is monitored to observe the dynamics of
topological contacts (N
topo
), relative contact order parameter (RCO), and the root mean square deviation (RMSD) from the real-protein native structure.
The folded structures of different model proteins (HP-36 and Aβ) resemble their respective real native state rather well. The dynamics of folding showsmultistage decay, with an initial hydrophobic collapse followed by a long plateau. Analysis ofN
topo
and RCO correlates the late stage folding with rearrangement of the side chain residues, particularly those far apart in
the sequence. The long plateau also signifies large entropic free energy barrier near the native state, as predicted from
theories of protein folding.
Dedicated to Professor C N R Rao on his 70th birthday 相似文献
7.
The mixing enthalpies of maltose with several typical α-amino acids (glycine, L-alanine, L-serine, L-valine, L-threonine and L-proline) and dilution enthalpies of each compound
have been determined in aqueous solutions at T=298.15 K by a flow-mixing microcalorimeter. The heterotactic enthalpic pairwise interaction coefficients, h
xy
, of each amino acid with maltose have been calculated by the McMillan–Mayer formalism, and are discussed in terms of intermolecular
interactions of the hydrated solute species. 相似文献
8.
G. Ozek T. Ozek K. H. C. Baser E. Hamzaoglu A. Duran 《Chemistry of Natural Compounds》2007,43(6):667-671
The component composition of essential oils produced by steam distillation from flower heads, leaves, and stems of Salvia anatolica (Lamiaceae), a recently described new species endemic from Turkey, was studied by GC/FID and GC/MS. A total of 127 volatile
components representing 96% of the oil was identified in essential oil from flower heads and leaves. It was found that the
principal oil components of flower heads and leaves were α-pinene (10.9%), β-pinene (6.7%), α-copaene (6.3%), heptacosane (6.2%), and hexadecanoic acid (5.0%). A total of 109 volatile compounds representing 87.9% of
the oil was characterized in essential oil isolated from stems. The principal oil components of stems were identified as hexadecanoic
acid (27.2%), tetradecanoic acid (15.2%), dodecanoic acid (5.5%), and α-copaene (5.0%).
__________
Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 552–555, November–December, 2007. 相似文献
9.
Keivan Majidzadeh-A Vahid Khalaj Davami Fatemeh Hemayatkar Mahdi Barkhordari Farzaneh Adeli Ahmad Fereidoun Mahboudi 《Applied biochemistry and biotechnology》2010,162(7):2037-2048
Human tissue plasminogen activator (t-PA) plays a pivotal role in the treatment of acute myocardial infarction, ischemic stroke,
and deep vein thrombosis. It has the benefit of generating no adverse effects such as fibrinogen depletion, systemic hemorrhage,
and immunologic reactions. Human t-PA is a serine-protease enzyme containing 527 amino acid residues in five structural domains.
The correct folding of t-PA requires the correct pairing of 17 disulfide bridges in the molecule. A gene encoding full-length
human t-PA was cloned into pPICZαA expression vector downstream of alcohol oxidase promoter and α-mating signal sequence from
Saccharomyces cerevisiae and flush with the kex2 cleavage site to express the protein with a native N terminus. The methylotrophic yeast, Pichia pastoris GS115 strain, was transformed with this cassette, and methanol utilizing (mut+) transformants were selected for production
and secretion of human t-PA into culture media. SDS–PAGE and Western blot analysis showed the expressed bands of t-PA protein.
Zymography test indicated suitable folding and proper function of the expressed recombinant human t-PA in conversion of plasminogen
to plasmin and gelatin lysis. Amidolytic activity test showed the amidolytic activity of 1,650 IU/ml. The results of this
study concluded that P. pastoris methylotrophic yeast can be a suitable alternative for mammalian and prokaryotic expression systems to produce t-PA. 相似文献
10.
Rey MW Brown KM Golightly EJ Fuglsang CC Nielsen BR Hendriksen HV Butterworth A Xu F 《Applied biochemistry and biotechnology》2003,111(3):153-166
Thielavia terrestris is a soil-borne thermophilic fungus whose molecular/cellular biology is poorly understood. Only a few genes have been cloned
from the Thielavia genus. We detected an extracellular glucoamylase in culture filtrates of T. terrestris and cloned the corresponding glaA gene. The coding region contains five introns. Based on the amino acid sequence, the glucoamylase was 65% identical to Neurospora crassa glucoamylase. Sequence comparisons suggested that the enzyme belongs to the glycosyl hydrolase family 15. The T. terrestris glaA gene was expressed in Aspergillus oryzae under the control of an A. oryzae α-amylase promoter and an Aspergillus niger glucoamylase terminator. The 75-kDa recombinant glucoamylase showed a specific activity of 2.8 μmol/(min·mg) with maltose
as substrate. With maltotriose as a substrate, the enzyme had an optimum pH of 4.0 and an optimum temperature of 60°C. The
enzyme was stable at 60°C for 30 min. The K
m
and k
cat
of the enzyme for maltotriose were determined at various pHs and temperatures. At 20°C and pH 4.0, the enzyme had a K
m
of 0.33±0.07 mM and a k
cat
of (5.5±0.5)×103 min−1 for maltotriose. The temperature dependence of k
cat
/K
m
indicated an activation free energy of 2.8 kJ/mol across the range of 20–70°C. Overall, the enzyme derived from the thermophilic
fungus exhibited properties comparable with that of its homolog derived from mesophilic fungi. 相似文献
11.
Bogar B Szakacs G Tengerdy RP Linden JC Pandey A 《Applied biochemistry and biotechnology》2002,102(1-6):453-461
Ten Aspergillus oryzae strains were screened in solid substrate fermentation for α-amylase production on spent brewing grain (SBG) and on corn fiber.
SBG proved to be a better substrate for enzyme production than corn fiber. A Plackett-Burman experimental design was used
to optimize the medium composition for the best strain. Solid substrate fermentation on optimized medium with A. oryzae NRRL 1808 (=ATCC 12892) strain in stationary 500-mL Erlenmeyer flask culture yielded 4519 U of α-amylase/g of dry matter
substrate in 3 d. The whole solid substrate fermentation material (crude enzyme, in situ enzyme) may be considered a cheap biocatalytic material for animal feed rations and for bioalcohol production from starchy
materials. 相似文献
12.
Chi‐Tsai Lin 《中国化学会会志》2015,62(5):443-448
2,3‐Butanediol dehydrogenase (Bdh) plays important roles in reduction of acetoin to 2,3‐butanediol, an important platform chemical with many industrial applications. Here, a TcBdh cDNA (1348 bp, GenBank accession JF896462) encoding a putative Bdh was cloned from Taiwanofungus camphorata. The deduced amino acid sequence is similar to the Bdhs from other species. A 3‐D structural model of TcBdh has been constructed based on the known structure of Pseudomonas putida formaldehyde dehydrogenase (PpFdh, PDB code 1KOL). To characterize the TcBdh protein, the coding region was subcloned into an expression vector pYEX‐S1 and transformed into Saccharomyces cerevisiae. The recombinant His6‐tagged TcBdh was expressed and purified by Ni2+‐nitrilotriacetic acid Sepharose. The purified enzyme showed a single band of 49 kDa on 12% sodium dodecyl sulfate‐polyacrylamide gel electrophoresis. The Michaelis constant (KM) value of the recombinant enzyme for acetoin was 8.5 mM. The enzyme’s optical pH was 6. The thermal inactivation of the enzyme showed a half‐life of 5.3 min at 45 °C. 相似文献
13.
I. M. Chung Mohd Ali A. Ahmad C. Y. Yu K. H. Ma J. G. Gwag Y. J. Park 《Chemistry of Natural Compounds》2005,41(6):650-653
One new compound 3,7,11,15,19-pentamethyl-9α,10α,11α,17α,18α-pentahydroxy-n-tetracosan-1-oxy-p-hydroxycaffeoate (oryzaterpenyl
caffeoate) (1), together with three known fatty acids linoleic acid, stearic acid and myristic acid were isolated and identified from the
rice grain of Oryza sativa. The structure of the new compound was elucidated by 1D and 2D NMR spectroscopic techniques (1H-1HCOSY, 1H-13C HETCOR) aided by EI-MS, and IR spectra.
__________
Published in Khimiya Prirodnykh Soedinenii, No. 6, pp. 535–537, November–December, 2005. 相似文献
14.
K. I. Kuchkova A. N. Aryku A. N. Barba P. F. Vlad 《Chemistry of Natural Compounds》2007,43(4):412-416
The dehydration products of driman-8α,11-diol-11-monoacetate that are formed upon reaction with several dehydrating agents and the products from elimination of
the C-8 acetoxy group in driman-8α,11-diol diacetate were investigated in detail. A new effective synthesis of drimenylacetate from driman-8α, 11-diol-11-monoacetate by its regioselective dehydration using methanesulfonic acid trimethylsilyl ether was developed.
__________
Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 340–343, July–August, 2007. 相似文献
15.
Wanli Liu Pengjun Shi Qiang Chen Peilong Yang Guozeng Wang Yaru Wang Huiying Luo Bin Yao 《Applied biochemistry and biotechnology》2010,162(1):1-12
A xylanase-encoding gene, xyn11F63, was isolated from Penicillium sp. F63 CGMCC1669 using degenerated polymerase chain reaction (PCR) and thermal asymmetric interlaced (TAIL)-PCR techniques.
The full-length chromosomal gene consists of 724 bp, including a 73-bp intron, and encodes a 217 amino acid polypeptide. The
deduced amino acid sequence of xyn11F63 shows the highest identity of 70% to the xylanase from Penicillium sp. strain 40, which belongs to glycosyl hydrolases family 11. The gene was overexpressed in Pichia pastoris, and its activity in the culture medium reached 516 U ml−1. After purification to electrophoretic homogeneity, the enzyme showed maximal activity at pH 4.5 and 40°C, was stable at
acidic buffers of pH 4.5–9.0, and was resistant to proteases (proteinase K, trypsin, subtilisin A, and α-chymotrypsin). The
specific activity, K
m, and V
max for oat spelt xylan substrate was 7,988 U mg−1, 22.2 mg ml−1, and 15,105.7 μmol min−1 mg−1, respectively. These properties make XYN11F63 a potential economical candidate for use in feed and food industrial applications. 相似文献
16.
Kh. M. Shakhidoyatov G. P. Genjemuratova E. Oripov 《Chemistry of Natural Compounds》2006,42(6):718-723
The reaction of deoxyvasicinone with acid chlorides of aliphatic (acetylbromide) and aromatic (benzoyl-, o-, p-methoxy-, p-nitrobenzoylchlorides) acids was studied. It was shown that 1-deoxyvasicinone salts were formed at room temperature; α-aroyloxymethylidenedeoxyvasicinones, in the presence of triethylamine at 80–85°C. It was found that acid chlorides cause
1-acyldeoxyvasicinone salts to transform into α-hydroxy-or α-aroyloxyarylidenedeoxyvasicinones, which indirectly confirmed their acylating properties. It was found that 1-acyldeoxyvasicinone
salts were effective acylating agents for alkaloids (cytisine, 1,2-dihydrodeoxyvasicinone) and amino acids (glycine, β-alanine, α-aminobutyric acid) and can be used to acylate primary and secondary aliphatic and heterocyclic amines.
__________
Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 585–589, November–December, 2006. 相似文献
17.
A. A. Akhunov Z. Golubenko E. Ch. Mustakimova N. A. Abdurashidova E. A. Pshenichnov S. O. Vshivkov 《Chemistry of Natural Compounds》2010,46(2):268-272
The effect of the phytohormones α-naphthylacetic acid and gibberellic acid on the protein content; glucansynthetase, peroxidase, and cellulase enzyme activity;
and development of gymnosperm and fuzzy cotton ovules was studied. The effect on cellulose synthesis of an inhibitor protein
isolated from integument of gymnosperm cotton treated with gibberellic acid was investigated. 相似文献
18.
Cloning, characterization, and expression of a new cry2Ab gene from Bacillus thuringiensis strain 14-1 总被引:2,自引:0,他引:2
Jain D Udayasuriyan V Arulselvi PI Dev SS Sangeetha P 《Applied biochemistry and biotechnology》2006,128(3):185-194
Bacillus thuringiensis is the major source for transfer of genes to impart insect resistance in transgenic plants. Cry2A proteins of B. thuringiensis are promising candidates for management of resistance development in insects owing to their difference from the currently
used Cry1A proteins, in structure and insecticidal mechanism. The cry2Ab gene was found to lack a functional promoter and, hence, is cryptic in nature. The cry2Ab7 gene was cloned from a new indigenous B. thuringiensis strain, 14-1. Nucleotide sequencing of the cry2Ab gene cloned from B. thuringiensis strain 14-1 revealed an open reading frame of 1902 bp. The deduced amino acid sequence of Cry2Ab of B. thuringiensis strain 14-1 showed a variation in three amino acid residues in comparison to the holotype sequence, Cry2Ab1. Expression of
the newly cloned cry2Ab gene was studied in an acrystalliferous strain of B. thuringiensis (4Q7) by fusing the cry2Ab gene downstream of cry2Aa promoter and orf1+orf2 sequences. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of a spore-crystal mixture obtained from transformants
of B. thuringiensis strain 4Q7 showed production of Cry2Ab protein of about 65 kDa. Alkali solubilized Cry2Ab7 protein showed toxicity against
Helicoverpa armigera neonates. 相似文献
19.
Five unusual hexose derivatives were isolated from the carbohydrate portion of the solid-state fermentation extract of Actinosynnema pretiosum ssp. auranticum ATCC 31565, which is a producing strain of maytansinoids that are a family of 19-membered macrocyclic lactams having extraordinary
cytotoxic and antineoplastic activities. Their structures were determined to be 2-deoxy-α-D-arabino-hexopyranose (1), 2-deoxy-β-D-arabino-hexopyranose (2), 3,6-anhydro-2-deoxy-α-D-arabino-hexcofuranose (3), 3,6-anhydro-2-deoxy-β-D-arabino-hexofuranose (4), and 2-(D-glycerol-1,2-dihydroxyethyl)furan (5) by NMR spectroscopic experiments.
Published in Khimiya Prirodnykh Soedinenii, No. 5, pp. 481–483, September-October, 2008. 相似文献
20.
Konsoula Z Liakopoulou-Kyriakides M Perysinakis A Chira P Afendra A Drainas C Kyriakidis DA 《Applied biochemistry and biotechnology》2008,149(2):99-108
A hyperthermophilic α-amylase encoding gene from Pyrococcus woesei was transferred and expressed in Xanthomonas campestris ATCC 13951. The heterologous α-amylase activity was detected in the intracellular fraction of X. campestris and presented similar thermostability and catalytic properties with the native P. woesei enzyme. The recombinant α-amylase was found to be stable at 90 °C for 4 h and within the same period it retained more than
50% of its initial activity at 110 °C. Furthermore, X. campestris transformants produced similar levels of recombinant α-amylase activity regardless of the carbon source present in the growth
medium, whereas the native X. campestris α-amylase production was highly dependent on starch availability and it was suppressed in the presence of glucose or other
reducing sugars. On the other hand, xanthan gum yield, which appeared to be similar for both wild type and recombinant X. campestris strains, was enhanced at higher starch or glucose concentrations. Evidence presented in this study supports that X. campestris is a promising cell factory for the co-production of recombinant hyperthermophilic α-amylase and xanthan gum. 相似文献