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1.
V. E. Kataev I. Yu. Strobykina O. V. Andreeva B. F. Garifullin R. R. Sharipova V. F. Mironov R. V. Chestnova 《Russian Journal of Bioorganic Chemistry》2011,37(4):483-491
Conjugates of the antituberculosis drug isoniazid (isonicotinyl hydrazine) and isomeric hydrazides of nicotinic and α-picolinic
acid with glycoside steviolbioside from the Stevia rebaudiana plant and the product of its acid hydrolysis, diterpenoid isosteviol, were synthesized. In addition, isosteviol hydrazide
and hydrazone derivatives as well as conjugates containing two isosteviol moieties joined by a dihydrazide linker were obtained.
The parental compounds and their synthetic derivatives were found to inhibit the in vitro growth of Mycobacterium tuberculosis (H37RV). The measured minimal concentrations of stevio-side and steviolbioside, at which the growth of M. tuberculosis was inhibited by 100% (MIC), were 7.5 and 3.8 μg/ml, respectively. MIC values for steviolbioside and isosteviol conjugates
with hydrazides of pyridine carbonic acid were within the ranges of 5–10 and 10–20 μg/ml, respectively. The maximal inhibitory
effect against M. tuberculosis was shown by the isosteviol conjugates with adipic acid dihydrazide (MIC 1.7 and 3.1 μg/ml). Antituberculosis activities
of the tested compounds were higher than the activity of antituberculosis drug Pyrizanamide (MIC 20 μg/ml) but lower than
that of antituberculosis drug isoniazid (MIC 0.02–0.04 μg/ml). 相似文献
2.
Nine newly synthetized isothiocyanate derivatives were demonstrated to posses antibacterial and genotoxic activitiesin vitro. 4-Hydroxybutyl isothiocyanate exhibited a broad antibacterial effect, with MIC values of 762 μmol/L forStaphylococcus aureus andEscherichia coli. Ethyl 4-methylsulfoxidobutanoate had the highest antibacterial activity in Gram-positive bacteria, the MIC value being 425
μmol/L forS. aureus. The highest tested concentrations of ethyl 4-isothiocyanatobutanoate and 4-hydroxybutyl isothiocyanate produced a bacteriocidal
effect in Gram-positive bacteria. The compounds showed no mutagenic effects onSalmonella typhimurium tester strains TA 98 and TA 100, either in the absence or in the presence of a metabolically active microsomal S9 fraction
from rat liver using standard Ames test. 相似文献
3.
Hee Y. Paik Hyojee Joung Joo Y. Lee Hong K. Lee Janet C. King Carl L. Keen 《Biological trace element research》1999,69(1):45-57
The present study focused on whether serum extracellular superoxide dimutase (EC-SOD) activity can be used as a functional
indicator of marginal zinc deficiency in humans. Subjects in this study were 444 healthy adults over 30 yr of age living a
normal rural life in Kyunggi province, Korea. The mean dietary zinc intake of subjects obtained from one 24-h recall was 6.41
± 4.35 mg and the average serum zinc concentration of the subjects was 11.06 ± 2.44 (μmol/L. Subjects were divided into three
groups by serum zinc concentrations: adequate (serum zinc >10.7 (μmol/L), low (serum zinc 9.0–10.7 μmol/L), and very low (serum
zinc <9.0 μmol/L) groups. A total of 50 subjects were selected from the three groups for analysis of EC-SOD activities. The
EC-SOD activity of subjects increased with increasing serum zinc concentrations, and the activities of the three groups were
significantly different as indicated by the Kruskal-Wallis test (p = 0.0239). Also, serum EC-SOD activities were significantly
correlated with serum zinc concentrations (r = 0.289,p = 0.04). Serum EC-SOD activities, however, were not significantly correlated to the dietary zinc intakes. In conclusion,
these results show that EC-SOD activities are decreased in subjects with low serum zinc concentrations and suggest that EC-SOD
activity may be a functional indicator of zinc nutritional status in humans. 相似文献
4.
Tatjana Mihajilov-Krstev Dragan Radnović Dušanka Kitić Bojan Zlatković Mihailo Ristić Suzana Branković 《Central European Journal of Biology》2009,4(3):411-416
Essential oil of Satureja hortensis L. was analyzed by GC and GC/MS and tested by a broth micro-well dilution method for activity against multiresistant clinical
isolates of pathogenic bacteria from 10 different genera: Klebsiella, Escherichia, Proteus, Staphylococcus, Streptococcus, Pseudomonas, Enterococcus, Enterobacter, Citrobacter and Acinetobacter. The main compounds in the oil were carvacrol (67%), γ-terpinene (15.3%) and p-cymene (6.73%). The oil showed activity against
all tested strains. MIC/MBC values were in the range of 0.78-25 μl/ml, with the exception of the strain P. aeruginosa. Microbicidal
concentration for this particular strain (50 μl/ml) was the highest tested concentration. The oil showed inhibitory and bactericidal
effect at the same concentration (MIC=MBC) for all but three strains. 相似文献
5.
Buatong Jirayu Phongpaichit Souwalak Rukachaisirikul Vatcharin Sakayaroj Jariya 《World journal of microbiology & biotechnology》2011,27(12):3005-3008
The aim of this work was to select endophytic fungi from mangrove plants that produced antimicrobial substances. Minimal inhibitory
concentrations (MIC) and minimal bactericidal concentrations (MBC) or minimal fungicidal concentrations (MFC) of crude extracts
from 150 isolates were determined against potential human pathogens by a colorimetric microdilution method. Ninety-two isolates
(61.3%) produced inhibitory compounds. Most of the extracts (28–32%) inhibited Staphylococcus aureus (MIC/MBC 4–200/64–200 μg ml−1). Only two extracts inhibited Pseudomonas aeruginosa (MIC/MBC 200/>200 μg ml−1). 25.5 and 11.7% inhibited Microsporum gypseum and Cryptococcus neoformans (MIC/MFC 4–200/8–200 μg ml−1 and 8–200/8–200 μg ml−1, respectively), while 7.5% were active against Candida albicans (MIC/MFC 32–200/32–200 μg ml−1). None of the extracts inhibited Escherichia coli. The most active fungal extracts were from six genera, Acremonium, Diaporthe, Hypoxylon, Pestalotiopsis, Phomopsis, and Xylaria as identified using morphological and molecular methods. Phomopsis sp. MA194 (GU592007, GU592018) isolated from Rhizophora apiculata showed the broadest antimicrobial spectrum with low MIC values of 8–32 μg ml−1against Gram-positive bacteria, yeasts and M. gypseum. It was concluded that endophytic fungi from mangrove plants are diverse, many produce compounds with antimicrobial activity
and could be suitable sources of new antimicrobial natural products. 相似文献
6.
The response of trout and zebrafish embryos to low and high boron concentrations is U-shaped 总被引:2,自引:0,他引:2
Fish in the embryo-larval stage of development have been shown to be sensitive to boron (B) at both ends of the dose-response
curve (1,2). The present study evaluated the health effects of low and high B concentrations on rainbow trout (Oncorhynchus mykiss), a cold water species, and zebrafish (Danio rerio), a warm water species. Rainbow trout embryos were incubated from day 1 until 2 wk posthatch in Type 1 ASTM ultrapure-grade
water (12.5°C) supplemented with only B (0-500 μM) as boric acid, or together with CaCO3 (0–2 mM) to increase water hardness. Embryonic growth was stimulated by B in a dose-dependent manner at all Ca concentrations
(p < 0.001). Chronic exposures below 9 μmol B/L impaired embryonic growth and above 10 mmol B/L caused death (p < 0.001). Thus, the safe range of exposure for the rainbow trout was between the adverse effect concentrations of 9 μmol
B/L and 10 mmol B/L. Zebrafish were maintained for 6 mo in ultrapure water containing <0.2 μmol B/L to determine the effect
of low-level exposure. High-level exposure was assessed by exposing zygotes, derived from parents maintained at 46 μmol B/L,
to graded concentrations of boric acid up to a concentration of 75 mmol B/L from fertilization until they were free feeding
(96 h). Fertilization occurred, but zygotes failed to survive when water contained <0.2 umol B/L (p < 0.001). Death occurred at and above 9.2 mmol B/L. Thus, the safe range of B exposure for zebrafish was between the adverse
effect concentrations of 0.2 μmol B/L and 9.2 mmol B/L. The dose-response for both species was thus U-shaped.
Part of this work was previously published in abstract form and presented at Experimental Biology 97, April 6–9, New Orleans,
LA (Eckhert, C. [1997] Embryonic trout growth and boron exposure,FASEB J.
11, A406 [abstract]). 相似文献
7.
The investigation of the recombinant bovine lactoferrin-derived antimicrobial protein (rBLfA) demonstrates that the inter-lobe
region of bovine lactoferrin contributes to iron binding stability and antimicrobial activity against Staphylococcus aureus. rBLfA containing N-lobe (amino acid residues 1–333) and inter-lobe region (residues 334–344) was expressed in Pichia pastoris at shaking flask and fermentor level. The recombinant intact bovine lactoferrin (rBLf) and N-lobe (rBLfN) were expressed
in the same system as control. The physical–chemical parameters of rBLfA, rBLfN and rBLf including amino acid residues, molecular
weight, isoelectric point, net positive charge and instability index were computed and compared. The simulated tertiary structure
and the calculated surface net charge showed that rBLfA maintained original structure and exhibited a higher cationic feature
than rBLf and rBLfN. The three proteins showed different iron binding stability and antimicrobial activity. rBLfA released
iron in the pH range of 7.0–3.5, whereas rBLfN lost its iron over the pH range of 7.0–4.0 and iron release from rBLf occurred
in the pH range of 5.5–3.0. However, the minimum inhibition concentration of rBLfA against S. aureus ATCC25923 was 6.5 μmol/L, compared with 12.5 and 25 μmol/L that of rBLfN and rBLf, respectively. These results revealed that
S. aureus was more sensitive to rBLfA than rBLfN and rBLf. It appeared that the strong cationic character of inter-lobe region related
positively to the higher anti-S. aureus activity. 相似文献
8.
Lead and catechol hematotoxicity in vitro using human and murine hematopoietic progenitor cells 总被引:1,自引:0,他引:1
In vitro cloning assays for hematopoietic myeloid and erythroid precursor cells have been used as screening systems to investigate
the hematotoxic potential of environmental chemicals in humans and mice. Granulocyte-monocyte progenitors (CFU-GM) from human
umbilical cord blood and from mouse bone marrow (Balb/c and B6C3F1) were cultured in the presence of lead and the benzene
metabolite catechol. Erythroid precursors (BFU-E) from human umbilical cord blood were cultured in the presence of lead. The
in vitro exposure of the human and murine cells resulted in a dose-dependent depression of the colony numbers. The concentration–effect
relationship was studied. Results showed that:
(1) Based on calculated IC50 values, human progenitors are more sensitive to lead and catechol than are murine progenitors.
The dose that caused a 50% decrease in colony formation after catechol exposure was 6 times higher for murine cells (IC50
= 24 μmol/L) than for human cord blood cells (IC50 = 4 μmol/L). Lead was 10–15 times more toxic to human hematopoietic cells
(IC50 = 61 μmol/L) than to murine bone marrow cells from both mice strains tested (Balb/c, IC50 = 1060 μmol/L; B6C3F1, IC50
= 536 μmol/L).
(2) A lineage specificity was observed after exposure to lead. Human erythroid progenitors (hBFU-E) (IC50 = 3.31 μmol/L) were
found to be 20 times more sensitive to the inhibitory effect of lead than were myeloid precursors (hCFU-GM) (IC50 = 63.58
μmol/L).
(3) Individual differences in the susceptibility to the harmful effect of lead were seen among cord blood samples.
(4) Toxicity of lead to progenitor cells occurred at environmentally relevant concentrations.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
9.
Phytase activity in rabbit cecal bacteria 总被引:1,自引:0,他引:1
The presence of phytase activity was demonstrated in 26 strains of rabbit cecal bacteria. In 25 strains a low phytase activity,
0.10–0.62 μmol phosphate released per min per mg protein, was found. High activity (2.61 μmol/min per mg protein) was found
in the strain PP2 identified as Enterococcus hirae. Phytase activity was cell-associated, being higher in the cell extract than in the cell walls. Extracellular phytase activity
and cell-associated phosphatase activity were not detected. Phytase activity was optimal around pH 5.0, which is below the
physiological cecal pH range. The K
m determined using the Lineweaver-Burk plot was 0.19 μmol/mL. Cations Fe3+, Cu2+ and Zn2+ at 0.5 mmol/L decreased phytase activity in sonicated cells of E. hirae by 99.4, 90.7 and 96.5 %, respectively. In contrast, Mg2+ increased activity by 11.0 %. Characteristics of E. hirae phytase (pH optimum, K
m, cation sensitivity) were similar to those of other bacterial phytases reported in the literature. Other bacteria with a
high phytase activity may be present in the rabbit cecum but remain to be identified. 相似文献
10.
Farombi EO 《Cell biology and toxicology》2006,22(3):159-167
The genotoxic effect of chloroquine (CQ), a 4-aminoquinoline antimalarial drug was investigated in rat liver cells using the
alkaline comet assay. Chloroquine (0–1000 μmol/L) significantly increased DNA strand breaks of rat liver cells dose-dependently.
Rat liver cells exposed to CQ (100–500 μmol/L) and treated with endonuclease III and formamidopyrimidine-DNA glycosylase,
the bacterial DNA repair enzymes that recognize oxidized pyrimidine and purine, respectively, showed greater DNA damage than
those not treated with the enzymes, providing evidence that CQ induced oxidation of purines and pyrimidines. Treatment of
cells with 5 mmol/L N-acetylcysteine, an intracellular reactive oxygen species (ROS) scavenger, and 100 μmol/L and 250 μmol/L deferoxamine, an
established iron chelator, significantly decreased the CQ-induced strand breaks and base oxidation, respectively. Similarly,
the formation of DNA strand breaks and oxidized bases was prevented by vitamin C (10 μmol/L) (a water-soluble antioxidant),
quercetin (50 μmol/L) (an antioxidant flavonoid), and kolaviron (30 μmol/L and 90 μmol/L) (an antioxidant and a liver hepatoprotective
phytochemical). The results indicate that the genotoxicity of CQ in rat liver cells might involve ROS and that free radical
scavengers may elicit protective effects in these cells. 相似文献
11.
Boris Lakatoš Barbora Kaliňaková Daniela Hudecová Ľudovít Varečka 《Central European Journal of Biology》2010,5(2):143-150
The thiazol dye Thioflavin T (ThT), which is used to stain amyloid fibrils, was found to have strong inhibitory effects on
both growth and conidiation of the deuteromycete Trichoderma viride at concentrations between 10–100 μg/ml (ca. 30–300 μmol/l). Thioflavin S (ThS), also known to stain amyloid fibrils, had no significant effect at these concentrations.
Both stains yielded a fluorescence response, but their distributions were different. ThT was non-homogenously distributed
throughout the cytoplasm, whereas ThS fluorescence was strongly bound to septal regions. The effect of ThT was studied on
several model microorganisms. It exerted a strong inhibitory effect on Staphylococcus aureus (Gram-positive bacterium) (MIC=10 μmol/l), but the effect on Escherichia coli (Gram-negative bacterium) was one order of magnitude less pronounced. The effect on Candida albicans was also very strong (MIC=50 μmol/l). The dermatophytic fungus Microsporum gypseum and deuteromycete Alternaria alternata were less affected by ThT (MIC=250 μmol/l and >500 μmol/l, respectively). These results show that ThT could be a useful inhibitor
of selected microorganisms, whereas ThS could be a useful agent for monitoring formation and maintenance of intrahyphal septa
without inhibiting the growth of the microorganism. 相似文献
12.
Riboflavin, suggested to be a radiosensitizer, was studied in murine thymocytes and human hepatoma L02 cell line in vitro with MTT method and fluorescence microscopy. When the murine thymocytes treated with 5–400 μmol/L riboflavin were irradiated
by 5 Gy 60Co γ ionizing radiation, the low concentration groups, i.e. treated with 5–50 μmol/L riboflavin, showed a different surviving
fractions-time relating correlation compared with the high concentration groups, i.e. treated with 100–400 μmol/L riboflavin.
The former had a high survival level at the end of irradiation, but which, after 4-h incubation, decreased rapidly to a low
level. On the contrary, the high concentration groups showed a low survival level at the end of irradiation, and a poor correlation
was found between the surviving fraction and the incubation time, after 4 h a little difference was observed. The results
of fluorescence microscopy indicated that under low concentration conditions, the riboflavin localized mainly in nucleus (both
perinuclear area and inside of nuclear membrane), while under high concentration conditions, intensive riboflavin also localized
around cytoplasmic membranes. Thus we can conclude: the riboflavin had radiosensitivity effect on DNA under low concentration
conditions, and enhanced the damage to cytoplasmic membrane under high concentration conditions. Also the most effective concentration
of riboflavin can be evaluated to be approximate 100 μmol/L. 相似文献
13.
Pattamarat Rattanachuay Duangporn Kantachote Manee Tantirungkij Teruhiko Nitoda Hiroshi Kanzaki 《World journal of microbiology & biotechnology》2011,27(4):869-880
In order to explore compounds naturallly inhibitory to shrimp pathogenic vibrios, a culture filtrate of Pseudomonas sp. W3 at a pH of 2 was extracted with ethyl acetate (EtOAc) to produce 82.15 mg/l of a yellow–brown extract (EtOAc-W3) that
had MIC values of 225-450 μg/ml against the growth of 18 shrimp pathogenic Vibrio harveyi strains. The MIC of EtOAc-W3 against the most pathogenic strain PSU 2015 was 450 μg/ml and this strain had the lowest LD50 (50% lethal dose) to pacific white shrimp (Litopenaeus vannamei, PL 21). At this MIC value, EtOAc-W3 in artificial sea water (ASW) killed strain PSU 2015; however in natural sea water,
only a partial growth inhibition was observed. The toxicity to pacific white shrimp and antivibrio activity of the EtOAc-W3
were investigated by conducting an experiment with 4 sets; native control (commercial ASW), EtOAc-W3 control (MIC/10, 45 μg/ml),
challenge (inoculation 6.0 × 106 c.f.u./ml PSU 2015) and treatment (6.0 × 106 c.f.u./ml PSU 2015 + 45 μg/ml EtOAc-W3). The same experiment was repeated by increasing the dose of EtOAc-W3 to 90 μg/ml
(MIC/5). Both concentrations of EtOAc-W3 tested had no toxicity to postlarval shrimps. A significant decrease in shrimp mortality
was observed over a 72 h period as approximately 80% of the shrimps died in each challenge set but only 63 and 23% died in
the presence of 45 and 90 μg/ml EtOAc-W3. The major component of EtOAc-W3 was supposed to be 2-heptyl-4-quinolone (HHQ) by
FAB-MS and 1H-NMR analyses of the purified fraction. 相似文献
14.
Magdalena Wegiera Urszula Kosikowska Anna Malm Helena D. Smolarz 《Central European Journal of Biology》2011,6(6):1036-1043
This study was designed primarily to investigate the antibacterial and antifungal activity of the extracts from fruits of
six Rumex L. species: R. acetosa L., R. acetosella L., R. confertus Willd., R. crispus L., R. hydrolapathum Huds. and R. obtusifolius L. The 7 Grampositive and 7 Gram-negative bacteria strains and 5 fungal ones were tested by agar and broth dilution method.
Determination of minimal inhibitory concentration (MIC) revealed that the extracts from R. confertus, R. crispus, R. hydrolapathum and R. obtusifolius exerted differential inhibitory effect on the growth of Gram-positive bacteria — staphylococci (MIC=62.5–125 μg/mL) and Gramnegative
bacteria — Escherichia coli ATCC 3521, Proteus mirabilis, Pseudomonas aeruginosa (MIC=125→500 μg/mL); MIC values determined by agar dilution method were somewhat higher. The same extracts inhibited also
the growth of fungi — Candida spp. or Trichophyton mentagrophytes ATCC 9533 (MIC=250–500 μg/mL), as found by agar dilution method. The total content of polyphenols (11.66–78.36 mg/g), anthracene
derivatives (0.26–12.93 mg/g) and tannins (4.00–11.16%) was also determined. 相似文献
15.
Photodynamic treatment by the cationic TMPyP photosensitizer was undertaken on the multiple antibiotic-resistant bacteria
Acinetobacter baumannii and Escherichia coli. Total eradication of the bacterial cultures was determined immediately after initiation of illumination when these bacteria
were treated with 5, 10, 15, 20-tetra (4-N methylpyridyl)porphine (TMPyP) at a concentration of 29.4 μmol/L and illuminated
by blue, green, or red light. Total eradication of both bacteria was obtained also after treatment of bacterial cultures with
3.7 μmol/L TMPyP and illumination with blue light (400–450 nm). On the other hand, an 8- or 16- to 20-fold higher light intensity,
respectively, was required for total eradication upon illumination with green (480–550 nm) or red light (600–700 nm). A 407-nm
blue light only 7 and 9 joules/cm2, respectively, was needed for total eradication of both bacteria even at a concentration of 3.7 μmol/L TMPyP. X-ray-linked
microanalysis demonstrated loss of potassium and a flood of sodium and chloride into the cells, indicating serious damage
to the cytoplasmic membrane. Transmission electron microscopy (TEM) revealed structural changes and damage to the membrane
of treated E. coli. In A. baumannii-treated cells, mesosomes and black dots that resemble aggregation of polyphosphate polymers could be seen. DNA breakage appeared
only after a long period of illumination, when the bacterial cell was no longer viable. It can be concluded that cytoplasmic
membrane damage and not DNA breakage is the major cause for bacterial death upon photosensitization.
Received: 13 October 2000 / Accepted: 17 November 2000 相似文献
16.
The effects of phosphorus, Zn2+, CO2, and light intensity on growth, biochemical composition, and the activity of extracellular carbonic anhydrase (CA) in Isochrysis galbana were investigated. A significant change was observed when the concentration of phosphorus in the medium was increased from
5 μmol/L to 1000 μmol/L affecting I. galbana’s cell density, biochemical composition, and the activity of extracellular CA. Phosphorous concentration of 50 μmol/L to 500
μmol/L was optimal for this microalgae. The Zn2+ concentration at 10 μmol/L was essential to maintain optimal growth of the cells, but a higher concentration of Zn2+ (≥ 1000 μmol/L) inhibited the growth of I. galbana. High CO2 concentrations (43.75 mL/L) significantly increased the cell densities compared to low CO2 concentrations (0.35 mL/L). However, the activity of extracellular CA decreased significantly with an increasing concentration
of CO2. The activity of extracellular CA at a CO2 concentration of 43.75 mL/L was approximately 1/6 of the activity when the CO2 concentration was at 0.35 mL/L CO2. Light intensity from 4.0 mW/cm2 to 5.6 mW/cm2 was beneficial for the growth, biochemical composition and the activity of extracellular CA. The lower and higher light intensity
was restrictive for growth and changed its biochemical composition and the activity of extracellular CA. These results indicate
that phosphorus, Zn2+, CO2, and light intensity are important factors that impact growth, biochemical composition and the activity of extracellular
CA in I. galbana. 相似文献
17.
Cultures able to dechlorinate cis-1,2-dichloroethene (cDCE) were selected with ethene (3–20%, v/v) as the sole source of carbon and energy. One mixed culture (K20) could degrade
cDCE (400 μmol l–1) or vinyl chloride (100 μmol l–1) in the presence of ethene (≤ 80 μmol l–1 and ≤ 210 μmol l–1, respectively). This culture consists of at least five bacterial strains. All five strains were able to degrade cDCE cometabolically in pure culture. The mixed culture K20 was highly tolerant against cDCE (up to 6 mmol l–1 in the liquid phase). Degradation of cDCE (200 μmol l–1) was not affected by the presence of trichloroethene (100 μmol l–1) or tetrachloroethene (100 μmol l–1). Transformation yields (Ty, defined as unit mass of chloroethene degraded per unit mass of ethene consumed) of the mixed culture K20 were relatively
high (0.51 and 0.61 for cDCE and vinyl chloride, respectively). The yield for cDCE with ethene as auxiliary substrate was ninefold higher than any values reported with methane or methane/formate as auxiliary
substrate. The viability of the cells of the mixed culture K20 (0.3 mg of cells ml–1) was unaffected by the transformation of ≤ 200 μmol l–1
cDCE in 300 min.
Received: 9 March 1999 / Accepted: 21 July 1999 相似文献
18.
M. Vanko D. Rauová L. Bezáková I. Holková F. Bilka M. Cupáková 《Biologia Plantarum》2012,56(1):105-110
Lipoxygenase (LOX) from opium poppy (Papaver somniferum L.) chloroplasts was isolated and 126.1-fold purified to electrophoretic homogeneity by combination of ion-exchange chromatography
on HA-Ultragel column and affinity chromatography on a linoleyl-aminopropyl agarose column. The relative molecular mass of the LOX determined
by SDS-PAGE was 92 kDa. Kinetic properties of purified LOX were determined in spectrophotometric assay by using of linoleic
acid (KM = 1.78 mM and Vmax = 11.4 μmol mg−1 min−1) and linolenic acid (KM = 1.27 mM and Vmax = 10.2 μmol mg−1 min−1). The optimum pH was 6.0 for both linoleic and linolenic acid dioxygenation catalyzed by LOX. HPLC analysis of the products
revealed a dual positional specificity of linoleic acid dioxygenation at pH 6.0 with ratio of 9- and 13-hydroperoxide products
being about 1:1. The activity of purified LOX was stimulated by Mg2+ and Ca2+. 相似文献
19.
J. Grones 《Folia microbiologica》1991,36(3):229-233
At a concentration of 0.5 to 3 mmol/L, ATP stimulates the activity of mitochondrial DNA polymerase ofNeurospora crassa under the optimum reaction conditions; at higher concentrations, an inhibitory effect is observed. 4-Chloromercuribenzoate
(1 mmol/L), a thiol inhibitor, decreases the enzyme activity two-fold, while N-ethylmaleimide (2 mmol/L) has no effect. Ethidium
bromide (up to 10 μmol/L) and heparin (up to 0.4 μg/mL) reduce the activity by 60%. ddTTP does not affect the DNA polymerase
reaction. The bestin vitro template is the activated calf-thymus DNA.
2nd report of the series Mitochondrial DNA polymerase from the poky mutant ofNeurospora crassa; 1st report:Biológia (Bratislava)
45, 601–606 (1990).
Translated by Č. Novotny 相似文献
20.
Conditions for an efficient high-yield procedure for the preparation of protoplasts fromTrichoderma viride have been determined. The optimum yield of protoplasts was obtained using 15–18-h-old unbranched mycelia, 0.7 mol/L KCl in
phosphate buffer (pH 6), and 5 % (W/V) of lyophilized snail gut-juice enzyme. The conversion of mycelia to protoplasts was complete within 40–60 min incubation
at 30 °C. 相似文献