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1.
Summary Growing cells of Tetrahymena thermophila (T. t.) metabolized, after 72 h, 80% of isosorbide dinitrate (ISDN) to isosorbide 5-mononitrate (5-ISMN) and isosorbide 2-mononitrate (2-ISMN) in a ratio 5-ISMN/2-ISMN=2.6 as evaluated by HPLC. The level of glutathione S-transferases (GSH-ST) determined by following the reactions with of 1-chloro-2,4-dinitrobenzene (CDNB), o-dinitrobenzene (o-DNB) or ISDN, showed the inductive effect of ISDN (0.5 mg/ml) on the level of this enzyme. The enzymatic activity, evaluated at 72 h, showed a twofold increase compared with the control. The GSH-ST activity correlated well with the rate of ISDN bioconversion. 相似文献
2.
Summary A total of 19 microorganisms, selected from genera of bacteria, fungi and yeasts, were screened for their ability to hydrolyse isosorbide dinitrate (ISDN) to mononitrates. Cunninghamella echinulata and Cunninghamella elegans showed rates of bioconversion of ISDN of 74% and 88% respectively, measured after 73 h. However, the two strains exhibited opposite stereoselectivity, as reflected in the ratios of isosorbide 5-mononitrate (5-ISMN) to isosorbide 2-mononitrate (2-ISMN). These were 2.57 and 0.75 for C. echinulata and C. elegans, respectively. 相似文献
3.
A common enzyme may be responsible for the conversion of organic nitrates to nitric oxide in vascular microsomes. 总被引:2,自引:0,他引:2
We compared the nitric oxide (NO)-generating behavior of nitroglycerin (NTG), pentaerythritol trinitrate (PEtriN) and isosorbide dinitrate (ISDN), in the microsomal preparation of bovine coronary artery smooth muscle cells. The comparative NO generating activities among these nitrates were consistent with their relative reported vasodilating activities. Consistent with our previous observations with NTG, 400 microM bromosulfophthalein did not affect NO generation from PEtriN and ISDN in vascular microsomes while 400 microM 1-chloro-2,4-dinitrobenzene completely inhibited NO generation from these nitrates. Gel filtration chromatography with solubilized microsomes of bovine aortic smooth muscle cells showed the primary activity of NO generation from all three nitrates to be eluted at about 200 kD, consistent with that found with solubilized microsomes from the bovine coronary artery microsomes. These results suggest that organic nitrates may be converted to NO by one common enzyme in vascular microsomes. 相似文献
4.
Marco P. C. Marques Joaquim M. S. Cabral Pedro Fernandes Dr. 《Biotechnology journal》2010,5(4):402-412
The microwell-scale approach is widely used for screening purposes and one-pot biotransformations, but it has seldom been applied to complex whole cell multistep bioconversions, requiring prolonged incubation periods. The present study aims to contribute to filling this gap. The side-chain cleavage of sitosterol to androstenedione (AD) with Mycobacterium sp. NRRL B-3805 cells was used as a model system, and focus was given to the screening of suitable bioconversion media with 24-well microwell plates. Results show that to perform this particular bioconversion growing cells are preferred over resting cells due to higher conversion yields obtained in aqueous medium. The use of resting cells may nevertheless present an interesting approach provided catalytic activity is retained throughout successive runs. Maintaining suitable aeration levels (air flow of 1 mL/min) allowed minimizing the decay of catalytic activity typically observed alongside consecutive bioconversion runs with resting cells. Microwell plates with dedicated oxygen and pH monitoring capabilities proved effective in media development for complex multistep bioconversions using relatively slow-growing bacteria. Under constant kLa (0.044/s) similar AD production and dissolved oxygen profiles were observed in microwell plates and in a bench-scale reactor. Selection of a suitable kLa value proved critical, since under lower kLa values scale-up proved unsuccessful. The same pattern was observed when other scale-up criteria were evaluated to perform the scale-up of this particular bioconversion. Results gathered seem to validate the proposed approach “from microwell plate to bench-scale fermentor”. 相似文献
5.
The 1,3-dinitrobenzene-degrading Rhodococcus strain QT-1 was isolated under nitrogen limiting conditions from contaminated soil samples. Experimental data indicate that 1,3-dinitrobenzene is metabolized via 4-nitrocatechol. Both compounds were oxidized by resting cells and nitro groups were completely eliminated as nitrite. Strain QT-1 utilizes both 1,3-dinitrobenzene and 4-nitrocatechol as source of nitrogen in the absence as well as in the presence of high amounts of ammonia. Growth on 4-nitrocatechol does not induce the enzyme(s) for the initial oxidation of 1,3-dinitrobenzene.Abbreviations TNT
2,4,6-trinitrotoluene
- 1,3DNB
1,3-dinitrobenzene
- 4NC
4-nitrocatechol
- 3NA
3-nitroaniline
- NB
nutrient broth; td doubling time
- OD546
optical density at 546 nm 相似文献
6.
Tadakazu Takeo 《Bioscience, biotechnology, and biochemistry》2013,77(6):1377-1379
The distribution of glutathione S-transferase (GST) (EC 2.5.1.18) in yeasts was investigated. High enzyme activity was found in some strains of Issatchenkia and Candida. Of 168 strains tested, Iss. orientalis showed the highest activity. The enzyme activity exists constitutively in the yeast cells but it increased with the addition of an enzyme substrate, o-dinitrobenzene, to the culture medium. Moreover, the addition of l-cysteine and glycine to the medium also increased the enzyme activity. This enzyme was so unstable that it lost almost all its activity on ammonium sulfate precipitation and 93% of its activity was lost when it was stored at 4°C for two weeks in a soluble state. We found that it was stabilized considerably in a solution containing 20% glycerol, 1 mm EDTA, 2 mm DTT and 10 mm sodium sulfite. 相似文献
7.
Yuanyuan Qu Hao Zhou Ang Li Fang Ma Jiti Zhou 《Applied microbiology and biotechnology》2011,89(3):655-663
Ferredoxin reductase BphA4 was well known as a component of biphenyl dioxygenase. However, there was little information about
whether it could utilize nonphysiological oxidants as electron acceptors. In the present study, we reported the novel nitroreductase
activity of BphA4LA−4. The homology model of ferredoxin reductase BphA4 from Dyella ginsengisoli LA−4 was constructed. According to the alignment of three-dimensional structures, it was supposed that BphA4LA−4 could function as nitroreductase. Recombinant His-tagged BphA4LA−4 was purified with a molecular mass of 49.6 ± 1 kDa. Biochemical characterization of purified BphA4LA−4 possessed the nitroreductase activity with the optimal temperature 50°C and pH 8.0. The substrate spectrum and kinetics indicated
BphA4LA−4 could reduce several nitroaromatics with different apparent K
m values: m-dinitrobenzene (560 μM), o-dinitrobenzene (1,060 μM), o-nitroaniline (1,570 μM), m-nitrobenzoic acid (1,300 μM) and m-nitrophenol (67 μM). The nitroreductase activity was further explained by docking studies, which was indicated that Arg 288
should play an important role in binding nitroaromatics. Moreover, there existed a good linear correlation between lnK
m and calculated binding energy. 相似文献
8.
Araceli Olivares Fernando Acevedo 《World journal of microbiology & biotechnology》2011,27(11):2513-2520
4-Androstene-3,17-dione (AD) and 1,4-androstadiene-3,17-dione (ADD) are the main precursors in the production of steroidal
drugs from phytosterols. To carry out the bioconversion, different inoculation strategies have been proposed. We compared
the use of whole fermented broth and of free resting cells of two mutant strains of Mycobacterium sp. (DSMZ2966 and DSMZ2967) in shake flasks. Also the effect of the nitrogen source (ammonium sulfate, ammonium chloride
and ammonium nitrate) and the sterol to biomass ratio at high substrate concentrations (19.2 g/l and 48.1 g/l) was evaluated.
We found that the bioconversion with free resting cells (cell pellets) is more efficient than that with whole fermented broth,
increasing both AD and ADD production. The use of ammonium nitrate in the culture medium and low substrate to biomass ratios
(close to 1.0) increased the production yield. We also found that the bioconversion can be run at high substrate concentration
under non-sterile conditions. 相似文献
9.
Total nucleic acids from sporulated oocysts of Eimeria tenella isolated from Changchun in China were found to contain three extrachromosomal double-stranded RNA segments (dsRNAs) of 1.4, 2.4 and 3.6 kb in sizes. These RNAs were resistant to RNase A digestion under high salt concentration (0.3 M NaCl). RNA-dependent RNA polymerase (RDRP) activity was detected in crude extracts of E. tenella sporulated oocysts containing these nucleic acid species. Virus-like particles (VLPs) were shown to have a diameter of approximately 38 nm under Electron Microscopy (EM) after purification by sucrose density gradient centrifugation. In keeping with the nomenclature generally adopted for protozoan viruses, we have named this isolate as E. tenella virus (ETV) which is the first virus isolated from E. tenella. 相似文献
10.
Continuous production of l(+)-tartaric acid from cis-epoxysuccinate using a membrane recycle reactor
The one-step bioconversion of cis-epoxysuccinate (CES) to l(+)-tartaric acid by dried Rhodococcus rhodochrous cells containing CES hydrolase activity was studied by using a continuous bioconversion process. The influence of the pH and the temperature was assessed. A mathematical model was used to quantify the CES hydrolase activity and stability. The optimal pH, which resulted in a maximal CES hydrolase activity and stability, was pH 8.0. A large increase in stability (half-life time) could be obtained when the temperature was decreased from 37 to 14°C during the continuous bioconversion. A total bioconversion was maintained for more than 100 days. This resulted in a large value for the specific productivity since the effect of the large increase in stability was much more important than the decrease of activity at the lower temperature. This continuous bioconversion process was further optimised by calculating the productivity for several continuously stirred tank reactors in series. The specific productivity could be nearly doubled when the number of reactors in the series was increased from 1 to 4. 相似文献
11.
Cantarella M Cantarella L Gallifuoco A Spera A 《Journal of industrial microbiology & biotechnology》2006,33(3):208-214
The biohydration of acrylonitrile, propionitrile and benzonitrile catalysed by the NHase activity contained in resting cells
of Microbacterium imperiale CBS 498-74 was operated at 5, 10 and 20°C in laboratory-scale batch and membrane bioreactors. The bioreactions were conducted
in buffered medium (50 mM Na2HPO4/NaH2PO4, pH 7.0) in the presence of distilled water or tap-water, to simulate a possible end-pipe biotreatment process. The integral
bioreactor performances were studied with a cell loading (dry cell weight; DCW) varying from 0.1 mgDCW per reactor to 16 mgDCW per reactor, in order to realize near 100% bioconversion of acrylonitrile, propionitrile and benzonitrile without consistent
loss of NHase activity. 相似文献
12.
Summary Microscopic observations of isotonic suspensions of human red blood cells demonstrate that cell shape is unaltered when the transmembrane electrical potential, orE
m
, is set in the range –85 to +10 mV with valinomycin at varied external K+, or K
o
.E
m
was measured with the fluorescent potentiometric indicator, diS-C3(5), as calibrated by a pH method. Repeating Glaser's experiments in which echinocytosis was attributed to hyperpolarization, we found that at low ionic strength the pH-dependent effects of amphotericin B appear to be unrelated toE
m
. The effects of increased intracellular Ca2+, or Ca
o
, on echinocytosis and onE
m
are separable. With Ca ionophore A23187 half-maximal echinocytosis occurs at greater Ca
o
than that which induces the half-maximal hyperpolarization associated with Ca-induced K+ conductance (Gardos effect). Thus, cells hyperpolarized by increased Ca
o
remain discoidal when Ca is below the threshold for echinocytosis. With A23187 and higher Ca
o
, extensive echinocytosis occurs in cells which are either hyperpolarized or at their resting potential. The Ca-activation curve for echinocytosis is left-shifted by low K
o
, a new observation consistent with increased DIDS-sensitive uptake of45Ca by hyperpolarized cells. These results support the following conclusions: (1) the shape and membrane potential of human red blood cells are independent under the conditions studied; (2) in cells treated with A23187, the Gardos effect facilitates echinocytosis by increasing Ca. 相似文献
13.
Nicholas F. Landolfi Joseph Leone James E. Womack Richard G. Cook 《Immunogenetics》1985,22(2):159-167
The endogenous neuraminidase activity of various mouse lymphoid subpopulations and tissue compartments was examined by a sensitive fluorometric assay. These analyses indicated that activated T lymphocytes possessed a significantly higher level of intracellular neuraminidase than activated B or resting T or B lymphocytes. Examination of the level of neuraminidase in bone marrow, thymus, lymph node, and unfractionated spleen indicated that these lymphoid tissues contained significantly less neuraminidase than was detected in stimulated T cells. Kinetic studies revealed that the majority of the increase in neuraminidase activity occurred between 24 and 48 h following stimulation. Analysis of activated T lymphocytes prepared from a panel of inbred mouse strains indicated that cells from mice of theH-2
v
haplotype, which possess theNeu-1
a allele and are deficient in liver neuraminidase, exhibited a level of activity which was significantly lower than that detected in stimulated T cells from other mouse strains. These results indicate that the endogenous neuraminidase activity of T lymphocytes increases upon stimulation, and that the level of this enzyme activity in lymphoid cells is also controlled by theNeu-1 locus, which is located in theH-2 region of the major histocompatibility complex.Abbreviations used in this paper MHC
major histocompatibility complex
- LPS
lipopolysaccharide
- DXS
dextran sulfate
- IL-2
interleukin 2
- NANA
N-acetylneuraminic acid
- sIg
surface immunoglobulin
- Con A
concanavalin A
- C57BL/10
B10 相似文献
14.
Ulf Ekelund Paul W. Franks Nicolas J. Wareham Jan man 《Obesity (Silver Spring, Md.)》2004,12(3):513-520
Objective: To test whether resting oxygen uptake (Vo2), submaximal Vo2, and maximal Vo2 (Vo2max) differs between obese adolescents (n = 18; BMI > 30) and a matched normal‐weight control group after adjustment for differences in fat‐free mass (FFM) and fat mass (FM). Research Methods and Procedures: FFM and FM were assessed by DXA. Resting Vo2, submaximal Vo2, and Vo2max were measured by indirect calorimetry. Results: There was no difference in resting Vo2 between groups after adjusting for FFM and FM. Submaximal Vo2 did not differ between groups after adjusting for body weight. Percentage Vo2max and NET Vo2 (Vo2max ? resting Vo2) were significantly higher in the obese group during submaximal exercise, however not after adjusting for body weight. Vo2max was not significantly different between groups after adjusting for FFM. Discussion: When body compositions are appropriately controlled for, resting Vo2, submaximal Vo2, and Vo2max do not differ between obese and normal‐weight adolescents. These data suggested that the higher relative Vo2 observed in obese adolescent subjects is due to their higher FM and not to an impaired Vo2max even though they may be less physically active. 相似文献
15.
Dr F Marinelli S Stella N Montanini F Le Monnier L Cavaletti E Selva 《Journal of industrial microbiology & biotechnology》1995,15(1):49-54
Streptomyces sp GE44282 was isolated in the course of a screening program for novel antibiotics. It co-produces heneicomycin and aurodox, two kirromycin-type antibiotics, which differ by the presence of an hydroxyl group at the C30 position of aurodox. Heneicomycin is converted into aurodox both by growing and resting cells ofStreptomyces sp GE44282 and by the producer of aurodox,Streptomyces goldiniensis ATCC 21386. This bioconversion of heneicomycin is substrate-specific and is not observed using the producer of heneicomycin,Streptomyces filippiniensis NRRL 11044. The three strains show very similar taxonomic characteristics. These results suggest that heneicomycin is a precursor of aurodox, the production of which depends on the bioconversion capability expressed by the strain. 相似文献
16.
Ashwini Kumar M. M. Husain Hasan Mukhtar C. R. Krishna Murti 《Journal of biosciences》1980,2(3):181-189
Glutathione-S-transferase (EC 2.5.1.18) activity was assayed in hepatic and extra-hepatic tissues of pigeons using l-chloro-2,4-dinitrobenzene
and 1,2-dichloro-4-nitrobenzene as substrates. Gluthathione-S-transferase activity towards 1-chloro-2,4-dinitrobenzene in
pigeon was in the order: kidney > liver > testes > brain > lung> heart. The enzyme activity with 1-chloro-2,4-dinitrobenzene
as substrate was 40–44 times higher in pigeon liver and kidney than that observed with 1,2-dichloro-4-dinitrobenzene as substrate.K
m values of hepatic and renal glutathione transferase with l-chloro-2,4-dinitrobenzene as substrate were 2.5 and 3 mM respectively.
Double reciprocal plots with varying reduced gluthathione concentrations resulted in biphasic curves with twoK
m values (liver 0.31 mM and 4mM; kidney 0.36 mM and 1.3 mM). The enzyme activity was inhibited by oxidized gluthathione in
a dose-dependent pattern. 3-Methylcholanthrene elicited about 50% induction of hepatic glutathione transferase activity whereas
phénobarbital was ineffective. 相似文献
17.
A putative glutathione S-transferase (GST) gene (bphK) was identified in the meta-cleavage operon for the degradation of m-toluate by Sphingomonas yanoikuyae B1. Disruption of bphK resulted in the loss of GST activity against 1-chloro-2,4-dinitrobenzene and a much increased lag time of the mutant strain
MB3 (bphK::Km) following subculture into m-toluate medium. In contrast, an increased lag time was not observed when MB3 was grown on biphenyl or m-xylene and MB3 showed normal growth on m-toluate when complemented with a subclone containing the bphK gene only. Furthermore, an additional GST activity was detected in MB3. The induction timing of this second GST activity
coincided with the beginning of the exponential growth phase of MB3 on m-toluate, reached maximal activity within three hours, and then dropped sharply to the basal level. Thus, it is apparent that
BphK and/or the second GST are necessary for optimal growth of B1 on m-toluate.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
18.
U. Maolepsza 《Journal of Phytopathology》2004,152(2):122-126
The objective of this study was to evaluate the effects of o‐hydroxyethylorutin on Botrytis cinerea mycelium growth and metabolism. Hydrogen peroxide concentration, superoxide dismutase, catalase and peroxidase activities were compared in the pathogens’ mycelium grown on control and o‐hydroxyethylorutin containing medium. Transfer of B. cinerea mycelium to medium supplemented with 5 mm o‐hydroxyethylorutin resulted in a large decrease in catalase activity. No changes in mycelium growth, hydrogen peroxide concentration and superoxide dismutase activity were observed. Guaiacol and ascorbate peroxidases were not detected in mycelia. The data are consistent with previous findings that o‐hydroxyethylorutin treatment of tomato plants restricts the development of B. cinerea infection due to the induction of higher active oxygen species (AOS) generation in plants by this compound. Being poor in catalase, the pathogen may not be able to cope with increasing AOS formation. The results indicate that catalase is an infective agent of B. cinerea. 相似文献
19.
《Bioscience, biotechnology, and biochemistry》2013,77(5):740-744
The reaction system for the bioconversion of dethiobiotin into biotin by resting cells and protoplasts of a Bacillus sphaericus bioB transformant was established. The reaction mixtures consisted of completely synthetic components, such as amino acids and metal salts. Among the sulfur compounds tested, L-CyS and L-cystine were effective in the biosynthesis of biotin from dethiobiotin both by resting cells and by protoplasts. The optimum concentrations of L-Cys were 2 to 3 mM and more than 0.25 mM for resting cell and protoplast systems, respectively. Vigorous shaking enhanced the biotin biosynthesis by protoplasts. The addition of yeast extract to the reaction mixture without a mixture of amino acids brought about a three-fold increase in the, amount of biotin synthesized by protoplasts when compard to the case with the reaction mixture containing the amino acid mixture. The amount of biotin synthesized by protoplasts increased with the incubation time up to 6 h and reached about 2 μg/ml. There was a clear correlation between the number of remaining protopiasts and their biotin-biosynthesizing activity during the incubation. 相似文献
20.
1,3-Dinitrobenzene (1,3-DNB) but not 1,2-dinitrobenzene (1,2-DNB) or 1,4-dinitrobenzene (1,4-DNB) is a potent testicular toxicant in rats. In vitro metabolism studies have established that 1,3-DNB is reduced to 3-nitroso-nitrobenzene (3-NNB), 3-nitrophenylhydroxylamine (3-NP) and 3-nitroaniline (3-NA) in testicular cytosol and Sertoli cell cultures. To establish a potential role for endogenous glutathione (GSH) in the detoxification of the electrophilic metabolite 3-NNB, we examined the chemical reaction of this compound with biological thiols, including GSH. The effect of pH and thiol concentration upon the reaction were studied. The reaction of GSH with 3-NNB was complex and gave three distinct products. These were identified as 3-NP, 3-NA and a glutathionyl derivative containing a covalently linked S-N bond. The hydroxyl amine and the amine were isolated and fully characterised. The glutathion-S-yl derivative was characterised in solution by proton NMR (400 MHz), infra-red and mass spectroscopy to establish its structure as the semimercaptal, N-(glutathion-S-yl)-N-hydroxy-3-nitroaniline (GSNOH-3NA). Similar reactions were performed with 4-nitrosonitrobenzene (4-NNB) to ascertain the reactivity of this chemical towards thiols. The addition of GSH to 4-NNB resulted in the rapid formation of 4-nitrophenylhydroxylamine (4-NP) and an adduct that was identified as the semimercaptal N-(glutathion-S-yl)-N-hydroxy-4-nitroaniline (GSNOH-4NA). 相似文献