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1.
B. A. Tashpulatova K. D. Dravranov L. G. Mezhlum'yan 《Chemistry of Natural Compounds》1992,27(6):735-739
The molecular mass (Mr) of highly purified glucose isomerase fromStreptomyces atratus has been determined. The native glucose isomerase, which has affinity for xylose, consists of an oligomeric protein containing 1552 amino acid residues and formed of four subunits. The enzyme is stable in the range of temperatures from 40 to 80°C and at pH values of from 6.0 to 11.0.Institute of Microbiology, Uzbek Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 833–837, November–December, 1991. 相似文献
2.
The influence of a number of bivalent metals on the activity ofStreptomyces atratus glucose isomerase has been studied. Mg2+ ions are activators and Co2+ ions are stabilizers of the glucose isomerase activity. The effective kinetic parameters for the action of the enzyme have been determined.Institute of Microbiology, Uzbek Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 838–842, November–December, 1991. 相似文献
3.
B. A. Tashpulatova Zh. Tashpulatov I. G. Sultanova N. Yu. Zukhrutdinova 《Chemistry of Natural Compounds》1995,30(5):619-621
The immobilization ofStreptomycs atratus glucose isomerase has been achieved and the periods of half-life of the immobilized glucose isomerase have been determined on various supports, among which the most acceptable are cotton lint and polyurethane. The stability of the immobilized preparations has been demonstrated.Institute of Microbiology, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (82712) 41 71 29. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 670–672, September–October, 1994. 相似文献
4.
A highly purified glucose isomerase with a specific activity 23.5 times greater than that of a homogenate of the mycelium has been obtained fromStreptomyces atratus by methods of homogenization from the freeze-dried biomass, heat treatment (70°C, 10 min), ion-exchange chromatography, and gel filtration. The yield of enzyme on the initial biomass was 51.8%. The molecular mass of the enzyme has been determined by various methods as 160 kDa but in the presence of sodium dodecyl sulfate in thin-layer PAG it amounts to 40 kDa.Institute of Microbiology, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 524–528, July–August, 1990. 相似文献
5.
Zh. T. Tashpulatov I. G. Sultanova Ya. U. Turabova 《Chemistry of Natural Compounds》1997,33(3):273-275
A method has been developed for obtaining glucose syrups from cellulose-containing plant wastes under the action of a complex of cellulases from a hybrid strain of fungus. Purified glucose syrups containing 19–20 mg/ml of reducing sugars have been obtained.Institute of Microbiology, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 41 71 29. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 358–361, May–June, 1997. 相似文献
6.
S. S. Deshmukh M. Dutta Choudhury V. Shankar 《Applied biochemistry and biotechnology》1993,42(2-3):95-104
Partially purified glucose isomerase fromStreptomyces thermonitrificans when coupled to glutaraldehyde-activated Indion 48-R, retained 30–40% activity of the soluble enzyme. However, an approximately
twofold increase in the activity could be achieved by binding the enzyme in the presence of glucose. Binding the enzyme to
matrices presaturated with either glucose or fructose and influence of lysine modification on the activity of the soluble
enzyme revealed that the comparatively low activity observed in case of the enzyme bound in the absence of substrate is the
result of the nonspecific binding of either substrate or product to the matrix. Immobilization did not affect the pH and temperature
optima of the enzyme, but it lowered the temperature stability. Immobilization resulted in a marginal increase in theK
m
and a threefold decrease in theV
max
. Substrate concentrations as high as 36% glucose could be converted to 18.5% fructose in 5 h, at pH 7.0 and 70‡C. The bound
enzyme, however, showed inferior stability to repeated use and lost approx 40% of its initial activity after five cycles of
use. Indion 48-R bound glucose isomerase could be stored, in wet state, for 30 d without any apparent loss in its initial
activity. 相似文献
7.
A method has been developed for obtaining glucose—fructose syrups by the hydrolysis of plant wastes under the action of a
complex of cellulases from a hybrid strain of a fungus, followed by isomerization of part of the glucose to fructose by immobilized
streptomycete glucose isomerase. The conditions for raising the degree of isomerization of the glucose and the period of half-inactivation
of the immobilized glucose isomerase have been optimized, with a simultaneous cheapening of the process. Plant raw materials
that have been used for obtaining glucose–fructose syrups are maize cobs, wheat or rice straw, and reeds. Isomerization has
been achieved by streptomycete cells immobilized on cotton lint.
Institute of Microbiology of the Academy of Sciences, Republic of Uzbekistan, Tashkent, fax (3712) 41 71 29. Translated from
Khimiya Prirodnykh Soedinenii, No. 4, pp. 449–451, July–August, 1998. 相似文献
8.
The capacity of the lectins ofDatura innoxia for being digested by proteases with various specificities and pH optima has been studied. Under the conditions of limited proteolysis the hemagglutinating activity did not decrease, and the degree of hydrolysis determined from the reaction with trinitrobenzenesulfonic acid was close to zero.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 89 14 75. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 93–95, January–February, 1996. Original article submitted July 3, 1995. 相似文献
9.
B. A. Tashpulatova K. D. Dravranov L. G. Mezhlum'yan 《Chemistry of Natural Compounds》1991,27(6):735-739
The molecular mass (Mr) of highly purified glucose isomerase fromStreptomyces atratus has been determined. The native glucose isomerase, which has affinity for xylose, consists of an oligomeric protein containing 1552 amino acid residues and formed of four subunits. The enzyme is stable in the range of temperatures from 40 to 80°C and at pH values of from 6.0 to 11.0. 相似文献
10.
The influence of a number of bivalent metals on the activity ofStreptomyces atratus glucose isomerase has been studied. Mg2+ ions are activators and Co2+ ions are stabilizers of the glucose isomerase activity. The effective kinetic parameters for the action of the enzyme have been determined. 相似文献
11.
L. V. Perminova G. A. Kovalenko T. V. Chuenko N. A. Rudina 《Kinetics and Catalysis》2012,53(1):145-153
Comparative studies have been carried out on the preparation of carbon-silica composite matrices for heterogeneous biocatalysts
with glucose isomerase activity. Carbon nanotubes and nanofibers have been included inside SiO2 xerogel. The enzymatic activity and operating stability of the biocatalysts have been investigated. Bacterial cells of a
recombinant glucose isomerase producer strain have been used as the enzymatically active component of the biocatalysts. The
steady-state activity of the biocatalysts subjected to “dry” cross linking with a glutaraldehyde solution (0.1–1%) is 1.5
times higher than the activity of the biocatalysts containing no nanocarbon. The initial and steady-state glucose-isomerase
activities of the biocatalysts at 70°C are ∼520–540 and ∼150–160 μmol min−1 g−1, respectively. The half-inactivation time of the biocatalysts under continuous monosaccharide (glucose, fructose) isomerization
conditions is up to ∼1500 h. 相似文献
12.
B. A. Tashpulatova Zh. Tashpulatov I. G. Sultanova N. Yu. Zukhrutdinova 《Chemistry of Natural Compounds》1994,30(5):619-621
The immobilization ofStreptomycs atratus glucose isomerase has been achieved and the periods of half-life of the immobilized glucose isomerase have been determined on various supports, among which the most acceptable are cotton lint and polyurethane. The stability of the immobilized preparations has been demonstrated. 相似文献
13.
N. A. Sosnina R. Sh. Khaziev I. I. Bandyukova A. V. Garusov O. V. Tsepaeva E. N. Ofitserov A. I. Konovalov 《Chemistry of Natural Compounds》1996,32(1):4-6
Pectin substances have been isolated from the epigeal pan of love-lies-bleeding,Amaranthus cruentus (A. caudatus), and have been characterized. The presence in them of galacturonic acid, galactose, rhamnose, xylose, arabinose, fructose, and glucose residues has been established. The titrimetric indices of the substances isolated have been determined and they have been studied by IR spectroscopy.Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 7–9, January–February, 1996. Original article submitted August 14, 1995. 相似文献
14.
An improved amperometric glucose biosensor based on glucose oxidase immobilized in sol–gel chitosan/silica hybrid composite film, which was prepared from chitosan (CS) and methyltrimethoxysilane (MTOS), on the surface of Prussian blue (PB)-modified glass carbon electrode was developed. The film was characterized by FT-IR. Effects of some experimental variables such as ratio of CS to silica, buffer pH, temperature, and applied potential on the current response of the biosensor were investigated. The biosensor fabricated under optimal conditions had a linear response to glucose over the range 5.0×10–5 to 2.6×10–2 M with a correlation coefficient of 0.9948 and a detection limit of 8.0×10–6 M based on S/N =3. The biosensor had a fast response time of less than 10 s, a high sensitivity of 420 nA mM–1, a long-term stability of over 60 days, and a good selectivity. The apparent Michaelis–Menten constant Km was found to be 3.2×10–3 M. The activation energy for enzymatic reaction was calculated to be 21.9 kJ mol–1. This method has been used to determine the glucose concentration in real human blood samples. 相似文献
15.
An endo-1, 4--glucanase consisting of a low-molecular-mass enzyme with a molecular mass of 19,862 Da has been isolated for the culture liquid of the hybrid fungusTrichoderma harzianum-G-1.Institute of Microbiology of the Academy of Sciences, Republic of Uzbekistan, Tashkent, fax (3712) 41 71 29. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 908–911, November–December, 1996. Original article submitted September 11, 1996. 相似文献
16.
Two pyrophosphatase isoenzymes with identical molecular weights but differing in the pH optima of their action and also in their senstivity to some bivalent metal ions have been isolated from extracts of the cotyledons of three-day cotton-plant shoots by gel filtration and ion-exchange chromatography.V. I. Lenin Tashkent State University. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 375–378, May–June, 1985. 相似文献
17.
I. I. Khamidov B. Tashkhodzhaev S. F. Aripova M. V. Telezhenetskaya A. K. Karimov 《Chemistry of Natural Compounds》1996,32(6):876-879
Two species of Berberis have yielded 10 isoquinoline alkaloids. In addition to known bases, two artifacts have been isolated — 8-trichloromethyldihydroberberine (I) and 8-trichloromethyldihydropalmatine. An x-ray structural analysis has been made of (1).Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 889–893, November–December, 1996. Original article submitted April 15, 1996. 相似文献
18.
M. S. Maksudov E. S. Maksimov Z. Saatov N. D. Abdullaev 《Chemistry of Natural Compounds》1996,32(4):539-541
A new iridoid – phlomoside D- has been isolated from the epigeal organs ofPhlomis regelii (M. Pop). Its structure has been established on the basis of chemical transformations and spectral characteristics.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 89 14 75. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 551–553, July–August, 1996. Original article submitted February 5, 1996. 相似文献
19.
pH and temperature play critical roles in multistep enzymatic conversions. In such conversions, the optimal pH for individual
steps differs greatly. In this article, we describe the production of glucoamylase (from Aspergillus oryzae MTCC152 in solid-state fermentation) and glucose isomerase (from Streptomyces griseus NCIM2020 in submerged fermentation), used in industries for producing high-fructose syrup. Optimum pH for glucoamylase was
found to be 5.0. For glucose isomerase, the optimum pH ranged between 7.0 and 8.5, depending on the type of buffer used. Optimum
temperature for glucoamylase and glucose isomerase was 50 and 60°C, respectively. When both the enzymatic conversions were
performed simultaneously at a compromised pH of 6.5, both the enzymes showed lowered activity. We also studied the kinetics
at different pHs, which allows the two-step reaction to take place simultaneously. This was done by separating two steps by
a thin layer of urease. Ammonia generated by the hydrolysis of urea consumed the hydrogen ions, thereby allowing optimal activity
of glucose isomerase at an acidic pH of 5.0. 相似文献
20.
Z. R. Akhmedova 《Chemistry of Natural Compounds》1996,32(3):374-380
Abstact Two bands with lignin peroxidase activity have been detected by isoelectric focusing in a total enzyme preparation obtained from a 15-day filtrate of the culture liquid of the fungusPleurotus ostreatus by fractionation with ammonium sulfate. Two homogeneous forms of the enzymes — LGP-I and LGP-II — have been obtained by gel filtration on Sephadex G-100, ion-exchange chromatography on DEAF-Toyopearl 650 M gel, and rechromatography on Sephadex G-75, and also by electrophoresis in PAAG. The specific activities of the purified lignin peroxidases LGP-I and LGP-H amounted to 36.5 and 54.3 units/mg, their degrees of purification being 8.7 and 12.9, respectively. The molecular masses of LGP-I and LGP-II, determined by electrophoresis in PAAG in the presence of Na-DS and by gel filtration on TSK HW–65 gel were 42–44 and 61–63 kDa. The isoelectric points of LGP-I and LGP-II were 3.4 and 4.1, their pH optima 2.7 and 3.4, and the, temperatures of their optimum enzymatic action 28 and 34°C, respectively. The isoenzymes differed from one another substantially with respect to pH stability and resistance to heat. The values of KM determined from the rates of hydrolysis of the substrate by the enzymes in the presence of H2O2 at pH 3.7 were 0.09 mM for LGP-I and 0.07 mM for LGP-II. The values of KM with respect to veratryl alcohol, determined by the Lineweaver—Burk method, were 0.117 mM for LGP-II and 0.132 mM for LGP-II.Institute of Microbiology, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 41 71 29. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 394–402, May–June, 1996. Original article submitted November 11, 1994. 相似文献