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1.
Complexes formed by reduced glutathione (GSH) with metal cations (Cr 2+, Mn 2+,Fe 2+,Co 2+,Ni 2+,Cu 2+,Zn 2+,Cd 2+,Hg 2+) were systematically investigated by the density functional theory (DFT). The results showed that the interactions of the metal cations with GSH resulted in nine different stable complexes and many factors had an effect on the binding energy. Generally, for the same period of metal ions, the binding energies ranked in the order of Cu 2+>Ni 2+>Co 2+>Fe 2+>Cr 2+>Zn 2+>Mn 2+; and for the same group of metal ions, the general trend of binding energies was Zn 2+>Hg 2+>Cd 2+. Moreover, the amounts of charge transferred from S or N to transition metal cations are greater than that of O atoms. For Fe 2+,Co 2+,Ni 2+,Cu 2+,Zn 2+,Cd 2+ and Hg 2+ complexes, the values of the Wiberg bond indices (WBIs) of M-S (M denotes metal cations) were larger than that of M-N and M-O; for Cr 2+ complexes, most of the WBIs of M-O in complexes were higher than that of M-S and M-N. Furthermore, the changes in the electron configuration of the metal cations before and after chelate reaction revealed that Cu 2+, Ni 2+,Co 2+ and Hg 2+ had obvious tendencies to be reduced to Cu +,Ni +,Co + and Hg + during the coordination process. 相似文献
2.
Kinetics and inhibition of Na +/K +-ATPase and Mg 2+-ATPase activity from rat synaptic plasma membrane (SPM), by separate and simultaneous exposure to transition (Cu 2+, Zn 2+, Fe 2+ and.Co 2+) and heavy metals (Hg 2+and Pb 2+) ions were studied. All investigated metals produced a larger maximum inhibition of Na +/K +-ATPase than Mg 2+-ATPase activity. The free concentrations of the key species (inhibitor, MgATP 2 ? , MeATP 2 ? ) in the medium assay were calculated and discussed. Simultaneous exposure to the combinations Cu 2+/Fe 2+ or Hg 2+/Pb 2+caused additive inhibition, while Cu 2+/Zn 2+ or Fe 2+/Zn 2+ inhibited Na +/K +-ATPase activity synergistically (i.e., greater than the sum metal-induced inhibition assayed separately). Simultaneous exposure to Cu 2+/Fe 2+ or Cu 2+/Zn 2+ inhibited Mg 2+-ATPase activity synergistically, while Hg 2+/Pb 2+ or Fe 2+/Zn 2+ induced antagonistic inhibition of this enzyme. Kinetic analysis showed that all investigated metals inhibited Na +/K +-ATPase activity by reducing the maximum velocities (V max) rather than the apparent affinity (K m) for substrate MgATP 2-, implying the noncompetitive nature of the inhibition. The incomplete inhibition of Mg 2+-ATPase activity by Zn 2+, Fe 2+ and Co 2+ as well as kinetic analysis indicated two distinct Mg 2+-ATPase subtypes activated in the presence of low and high MgATP 2 ? concentration. EDTA, L-cysteine and gluthathione (GSH) prevented metal ion-induced inhibition of Na +/K +-ATPase with various potencies. Furthermore, these ligands also reversed Na +/K +-ATPase activity inhibited by transition metals in a concentration-dependent manner, but a recovery effect by any ligand on Hg 2+-induced inhibition was not obtained. 相似文献
3.
The effect of heavy metal cations on the mitochondrial ornithine/citrulline transporter was tested in proteoliposomes reconstituted
with the protein purified from rat liver. The transport activity was measured as [ 3H]ornithine uptake in proteoliposomes containing internal ornithine (ornithine/ornithine antiport mode) or as [ 3H]ornithine efflux in the absence of external substrate (ornithine/H + transport mode). 0.1 mM Cu 2+, Pb 2+, Hg 2+, Cd 2+ and Zn 2+ strongly inhibited (more than 85%) the antiport; whereas Mn 2+, Co 2+ and Ni 2+ inhibited less efficiently (25, 47 and 69%, respectively). The IC 50 values of the transporter for the different metal ions ranged from 0.71 to 350 μM. Co 2+ and Ni 2+ also inhibited the [ 3H]ornithine efflux whereas Cu 2+, Pb 2+, Hg 2+, Cd 2+ and Zn 2+ stimulated the [ 3H]ornithine efflux. The stimulation of the [ 3H]ornithine efflux by Cu 2+ and Cd 2+ (as well as by Pb 2+, Hg 2+ and Zn 2+) was not prevented by NEM and was reversed by DTE. These features indicated that the inhibition of the antiport was due to
the interaction of the Cu 2+, Pb 2+, Hg 2+, Cd 2+ and Zn 2+ with a population of SH groups, of the transporter, responsible for the inhibition of the physiological function; whereas
the stimulation of [ 3H]ornithine efflux was due to the induction of a pore-like function of the transporter caused by interaction of cations with
a different population of SH groups. Differently, the inhibition of the ornithine transporter by Ni 2+, Co 2+ or Mn 2+ was caused by interaction with the substrate binding site, as indicated by the competitive or mixed inhibition. 相似文献
4.
Prokaryotic enzymes formamidopyrimidine-DNA glycosylase (Fpg) and endonuclease VIII (Nei) and their eukaryotic homologs NEIL1,
NEIL2, and NEIL3 define the Fpg family of DNA glycosylases, which initiate the process of repair of oxidized DNA bases. The
repair of oxidative DNA lesions is known to be impaired in vivo in the presence of ions of some heavy metals. We have studied the effect of salts of several alkaline earth and transition
metals on the activity of Fpg-family DNA glycosylases in the reaction of excision of 5,6-dihydrouracil, a typical DNA oxidation
product. The reaction catalyzed by NEIL1 was characterized by values K
m = 150 nM and k
cat = 1.2 min −1, which were in the range of these constants for excision of other damaged bases by this enzyme. NEIL1 was inhibited by Al 3+, Ni 2+, Co 2+, Cd 2+, Cu 2+, Zn 2+, and Fe 2+ in Tris-HCl buffer and by Cd 2+, Zn 2+, Cu 2+, and Fe 2+ in potassium phosphate buffer. Fpg and Nei, the prokaryotic homologs of NEIL1, were inhibited by the same metal ions as NEIL1.
The values of I 50 for NEIL1 inhibition were 7 μM for Cd 2+, 16 μM for Zn 2+, and 400 μM for Cu 2+. The inhibition of NEIL1 by Cd 2+, Zn 2+, and Cu 2+ was at least partly due to the formation of metal-DNA complexes. In the case of Cd 2+ and Cu 2+, which preferentially bind to DNA bases rather than phosphates, the presence of metal ions caused the enzyme to lose the
ability for preferential binding to damaged DNA. Therefore, the inhibition of NEIL1 activity in removal of oxidative lesions
by heavy metal ions may be a reason for their comutagenicity under oxidative stress. 相似文献
5.
A partial characterization of human term placental 3ß-HSDH in mitochondria is reported. Apparent KM of pregnenolone: 70 nM. A dose-dependent stimulation of 3ß-HSDH by NAD + or NADP + was observed in the range from 10 −6 to 10 −3 M ( KM value of NAD +: 20 μM). At equimolar concentrations NAD + is more than 10-fold as effective a cofactor of the 3ß-HSDH than NADP +. pH optimum: 9.5 (glycine-NaOH buffer). Temperature optimum 40–45°C. A rapid loss of 3ß-HSDH activity was found after preincubation of the enzyme at 37°C after 30 min: less than 50% of initial enzyme activity is present. No inhibition was obtained by Mg 2+, Ca 2+ Sr 2+ and Ba 2+ (1–100 mM). A strong inhibition was achieved with 1 mM Zn 2+, Cd 2+, Cu 2+ and 10 mM and 100 mM Fe 2+, Mn 2+, Co 2+ and Ni 2+. 相似文献
6.
Effects of heavy metals on the isopod Asellus aquaticus (L.) are studied by static toxicity tests. Results demonstrate that the species is sensitive to Cd +2, Cr +6, Cu +2, Fe +3, Hg +2, Ni +2 Pb +2 and Zn +2, but the toxicity of each metal is different. Differences are also found between adults and between adults and juveniles. The comparative analysis of all data on the toxicity has been performed on the concentrations of metal ions and not on metal compound concentrations.Criteria for establishing water quality in order to guarantee protection of the environment are discussed. 相似文献
7.
Glutathione reductase (GR; E.C. 1.6.4.2) is a flavoprotein that catalyzes the NADPH-dependent reduction of oxidized glutathione (GSSG). In this study we tested the effects of Al 3+, Ba 2+, Ca 2+, Li +, Mn 2+, Mo 6+, Cd 2+, Ni 2+, and Zn 2+ on purified bovine liver GR. In a range of 10?μM–10?mM concentrations, Al 3+, Ba 2+, Li +, Mn 2+, and Mo 6+, and Ca 2+ at 5?μM–1.25?mM, had no effect on bovine liver GR. Cadmium (Cd 2+), nickel (Ni 2+), and zinc (Zn 2+) showed inhibitory effects on this enzyme. The obtained IC 50 values of Cd 2+, Ni 2+, and Zn 2+ were 0.08, 0.8, and 1?mM, respectively. Cd 2+ inhibition was non-competitive with respect to both GSSG ( KiGSSG 0.221?±?0.02?mM) and NADPH ( KiNADPH 0.113?±?0.008?mM). Ni 2+ inhibition was non-competitive with respect to GSSG ( KiGSSG 0.313?±?0.01?mM) and uncompetitive with respect to NADPH ( KiNADPH 0.932?±?0.03?mM). The effect of Zn 2+ on GR activity was consistent with a non-competitive inhibition pattern when the varied substrates were GSSG ( KiGSSG 0.320?±?0.018?mM) and NADPH ( KiNADPH 0.761?±?0.04?mM), respectively. 相似文献
8.
Essentially all bacteria have genes for toxic metal ion resistances and these include those for Ag+, AsO
−2
, AsO
3−4
, Cd2+, Co2+, CrO
2−4
, Cu2+, Hg2+, Ni2+, Pb2+, TeO
2−3
, Tl+ and Zn2+. The largest group of resistance systems functions by energy-dependent efflux of toxic ions. Fewer involve enzymatic transformations (oxidation, reduction, methylation, and demethylation) or metal-binding proteins (for example, metallothionein SmtA, chaperone CopZ and periplasmic silver binding protein SilE). Some of the efflux resistance systems are ATPases and others are chemiosmotic ion/proton exchangers. For example, Cd2+-efflux pumps of bacteria are either inner membrane P-type ATPases or three polypeptide RND chemiosmotic complexes consisting of an inner membrane pump, a periplasmic-bridging protein and an outer membrane channel. In addition to the best studied three-polypeptide chemiosmotic system, Czc (Cd2+, Zn2+, and Co2), others are known that efflux Ag+, Cu+, Ni2+, and Zn2+. Resistance to inorganic mercury, Hg2+ (and to organomercurials, such as CH3Hg+ and phenylmercury) involve a series of metal-binding and membrane transport proteins as well as the enzymes mercuric reductase and organomercurial lyase, which overall convert more toxic to less toxic forms. Arsenic resistance and metabolizing systems occur in three patterns, the widely-found ars operon that is present in most bacterial genomes and many plasmids, the more recently recognized arr genes for the periplasmic arsenate reductase that functions in anaerobic respiration as a terminal electron acceptor, and the aso genes for the periplasmic arsenite oxidase that functions as an initial electron donor in aerobic resistance to arsenite. 相似文献
9.
Glutathione S-transferases (GSTs) are an important enzyme family which play a critical role in detoxification system. In our study, GST was purified from muscle tissue of Chalcalburnus tarichii Pallas with 301.5-fold purification and 19.07% recovery by glutathione agarose affinity chromatography. The purity of enzyme was checked by sodium dodecyl sulfate–polyacrylamide gel electrophoresis, showing a two band, because of having heterodimer structure. KM values were 1.59 and 0.53?mM for 1-chloro-2,4-dinitrobenzene (CDNB) and glutathione (GSH), respectively. Vmax values for CDNB and GSH were also determined as 5.58 and 1.88?EU/mL, respectively. In addition, inhibition effects of Ag +, Cu 2+, Cd 2+, Fe 3+, Pb 2+, Cr 2+, Co 2+ and Zn 2+ metal ions were investigated on the enzyme activity and IC 50, K i values were calculated for these metal ions. 相似文献
10.
We prepared an aminothiourea‐derived Schiff base (DA) as a fluorescent chemosensor for Hg 2+ ions. Addition of 1 equiv of Hg 2+ ions to the aqueous solution of DA gave rise to an obvious fluorescence enhancement and the subsequent addition of more Hg 2+ induced gradual fluorescence quenching. Other competing ions, including Pb 2+, Cd 2+, Cr 3+, Zn 2+, Fe 2+, Co 3+, Ni 2+, Ca 2+, Mg 2+, K + and Na +, did not induce any distinct fluorescence changes, indicating that DA can selectively detect Hg 2+ ions in aqueous solution. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
11.
Two extracellular peroxidases from Phanerochaete chrysosporium, namely a lignin peroxidase (LiP) and manganese peroxidase (MnP), were purified simultaneously by applying successively, ultrafiltration, ion-exchange and gel filtration chromatography. LiP and MnP have a molecular mass of 36 and 45 kDa, respectively. The optimal pHs for LiP and MnP activities were 3.0 and 4.5, respectively. Both peroxidases showed maximal activity at 30 °C and moderate thermostability. MnP activity was strongly inhibited by Fe 2+, Zn 2+, Mg 2+ and Hg 2+, and enhanced by Mn 2+, Ca 2+ and Cu 2+. LiP activity was enhanced by Ca 2+, Na + and Co 2+ and it was inhibited in the presence of K +, Hg +, Fe 2+, Mg 2+ and high concentrations of Cu 2+ and Zn 2+. The Km and Vmax for LiP toward veratryl alcohol as a substrate were 0.10 mM and 15.2 U mg −1, respectively and for MnP toward Mn 2+, they were respectively 0.03 mM and 25.5 U mg −1. The two peroxidases were also able to break down rice lignin in a small-scale solid state treatment system. Data suggest these two peroxidases may be considered as potential candidates for the development of enzyme-based technologies for lignin degradation. 相似文献
12.
Properties of partially purified NADP-malic enzyme (EC 1.1.1.40) from glumes of developing wheat grains were examined. The pH optimum for enzyme activity was influenced by malate and shifted from 7.3 to 7.6 when the concentration of malate was increased from 2 to 10 mM. The Km values, at pH 7.3, for various substrates were: malate, 0.76 mM; NADP, 20 μM and Mn 2+, 0.06 mM. The requirement of Mn 2+ cation for enzyme activity could be partially replaced by Mg 2+ or Co 2+. Mn 2+ dependent enzyme activity was inhibited by Pb 2+, Ni 2+, Hg 2+, Zn 2+, Cd 2+, Al 3+ and Fe 3+. During the reaction, substrate molecules (malate and NADP) reacted with enzyme sequentially. Activity of malic enzyme was inhibited by products of the reaction viz pyruvate, HCO 3? and NADPH 2. At a limiting fixed concentration of NADP, these products induced a positive cooperative response to increasing concentrations of malate. 相似文献
13.
In liver homogenate the biosynthesis of N-acetylneuraminic acid using N-acetylglucosamine as precursor can be followed stepwise by applying different chromatographic procedures. In this cell-free system 16 metal ions (Zn 2+, Mn 2+, La 3+, Co 2+, Cu 2+, Hg 2+, VO
3
–
, Pb 2+, Ce 3+, Cd 2+, Fe 2+, Fe 3+, Al 3+, Sn 2+, Cs + and Li +) and the selenium compounds, selenium(IV) oxide and sodium selenite, have been checked with respect to their ability to influence a single or possible several steps of the biosynthesis of N-acetylneuraminic acid. It could be shown that the following enzymes are sensitive to these metal ions (usually applied at a concentration of 1 mmoll –1): N-acetylglucosamine kinase (inhibited by Zn 2+ and vandate), UDP- N-acetylglucosamine-2-epimerase (inhibited by zn 2+, Co 2+, Cu 2+, Hg 2+, VO
3
–
, Pb 2+, Cd 2+, Fe 3+, Cs +, Li +, selenium(IV) oxide and selenite), and N-acetylmannosamine kinase (inhibited by Zn 2+, Cu 2+, Cd 2+, and Co 2+). Dose dependent measurements have shown that Zn 2+, Cu 2+ and selenite are more efficient inhibitors of UDP- N-acetylglucosamine-2-epimerase than vanadate. As for the N-acetylmannosamine kinase inhibition, a decreasing inhibitory effect exists in the following order Zn 2+, Cd 2+, Co 2+ and Cu 2+. In contrast, La 3+, Al 3+ and Mn 2+ (1 mmoll –1) did not interfere with the biosynthesis of N-acetylneuraminic acid. Thus, the conclusion that the inhibitory effect of the metal ions investigated cannot be regarded as simply unspecific is justified.Dedicated to Professor Theodor Günther on the occasion of his 60th birthday 相似文献
14.
Despite technological developments and improved liner-material applications, heavy metals in landfill leachate still penetrate the soil profile, polluting the soil and ground-water. An alternative approach therefore must be explored to reduce heavy-metal migration in soil-bentonite landfill liners. By considering the interaction of different heavy metals and their synergetic and antagonistics behaviors, such an approach could be developed. Low mobility metals such as Cu 2+, and Pb 2+ inhibit the adsorption of Cd 2+ which is a moderate-mobility metal and Cu 2+ sorption is decreased by the presence of Zn 2+ and Cd 2+. Therefore, Zn 2+, a low-mobility metal, cannot be grouped with Cu 2+. This way, four compatible metal groups have been identified: (1) low mobility: Pb 2+, Cu 2+, and Ag, (2) low mobility: Zn 2+ and Cr 3+; (3) moderate mobility: As 2+, Fe 2+, and Ni 2+; (4) high mobility: Cd 2+ and Hg 2+. Cd 2+ with a moderate mobility pattern is synergetic to Fe 2+ and is more mobile with Ni 2+. Therefore, Cd 2+ is separated from the moderate-mobility group and is consigned with Hg, a high-mobility metal. The liner materials suitable for Hg 2+ are assumed to be suitable for Cd 2+ as well. Based on this concept, and to reduce heavy metal mobility, wastes should be segregated on compatibility basis according to their heavy metal contents before being disposed in different individual compartments. For wastes containing several incompatible heavy metals, sorting should be based on the heavy-metal with the highest concentration. Another solution is the manufacturing of products using compatible heavy metal combinations and then labeling them accordingly. Such waste segregation and landfill compartmentalization lowers risks of groundwater contamination and liner cost. 相似文献
15.
Novel phenanthroline Schiff base fluorescent sensors L1 , L2 , and D1 were designed and synthesized. The sensing abilities of the compounds in the presence of metal cations (Li +, Na +, K +, Ag +, Mg 2+, Ba 2+, Ca 2+, Mn 2+, Pb 2+, Hg 2+, Ni 2+, Zn 2+, Cd 2+, Co 2+, Cu 2+, Cr 3+, Fe 3+, Fe 2+, Al 3+, and Eu 3+) were studied by UV‐vis and fluorescent spectroscopy. The compounds L1 , L2 , and D1 could act as Eu 3+ ion turn‐off fluorescent sensors based on ligand‐to‐metal binding mechanism in DMSO‐H 2O solution (v/v = 1:1, 10 mM Tris, pH = 7.4). Additionally, the L1 –Eu 3+ and D1 –Eu 3+ complexes could be applied as turn‐on enantioselective sensors sensing of malate anion isomers with color changes. Furthermore, biological experiments using living PC‐12 cells demonstrated that L1 and D1 had excellent membrane permeability and could be used as effective fluorescent sensors for detecting Eu 3+ and malate anion in living cells. 相似文献
16.
This paper reports the synthesis of azomethine-modified gold nanoparticles with azomethine (azomethine-AuNPs) in aqueous media, which were characterized by FT-IR spectroscopy, ultraviolet–visible spectroscopy (UV-Vis), dynamic light scattering (DLS), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). The azomethine-AuNPs were employed as colorimetric for Cr3+ and Co2+ ions at pH 6.2–7.5 and 8.1–9.1, at room temperature in aqueous solution. In the presence of Cr3+ and Co2+, the azomethine-AuNPs induce aggregation of the nanoparticles. Upon aggregation, the surface plasmon absorption band red-shifts so that the nanoparticle solution appears a blue color. The sensitivity of azomethine-AuNPs towards other metal ions, Mg2+, Mn2+, Cr6+, Na+, Ni2+, Ag+, Al3+, Ca2+, Cd2+, Cu2+, Fe2+, Fe3+, Hg2+, Cd2+, K+, Co3+, Ni2+, Pb2+, and Zn2+ are negligible. This highly selective sensor allows a direct quantitative assay of Co2+ and Cr3+ with colorimetric detection limits of 83.22 and 108 nM, respectively. 相似文献
17.
Chloride salts of Li +, Na +, K +, Mg 2+, Ca 2+, Cr 3+, Mn 2+, Fe 2+, and Fe 3+ had no effect on [ 3H]diazepam binding. Chloride salts of Co 2+, Ni 2+, Cu 2+, and Zn 2+ increased [ 3H]diazepam binding by 34 to 68% in a concentration-dependent fashion. Since these divalent cations potentiated the GABA-enhanced [ 3H]diazepam binding and the effect of each divalent cation was nearly additive with GABA, these cations probably act at a site different from the GABA recognition site in the benzodiazepine-receptor complex. Scatchard plots of [ 3H]diazepam binding without an effective divalent cation showed a single class of binding, with a Kd value of 5.3 mM. In the presence of 1 mM Co 2+, Ni 2+, Cu 2+, or Zn 2+, two distinct binding sites were evident with apparent Kd values of 1.0 nM and 5.7 nM. The higher-affinity binding was not detected in the absence of an effective divalent cation and is probably a novel, super-high-affinity binding site. 相似文献
18.
Summary Six major components exhibiting endo-1,4-\- d-glucanase activity were partially purified from culture filtrates of a newly isolated Cellulomonas sp. using ion-exchange chromatography. Molecular weights (44,000 to 140,000), pH optima (6.0 to 7.0), temperature optima (40 to 50°C), half-life, energy of activation, K
mand other kinetic parameter investigations indicate the existence of 6 different endoglucanases.Further support for this assumption comes from inhibition studies, whereby glucose inhibited the enzyme activities between 15 and 50% at a concentration of 0.034% (1.65 mM) and cellobiose between 0 and 50% at a concentration of 0.1% (2.92 mM). Of all the metals (Hg 2+, Co 2+, Cu 2+, Ca 2+, Mg 2+, Zn 2+, Fe 3+) tested, only Hg 2+ exhibited a 55% inhibition at 5.0 mM. 相似文献
19.
Glutathione S‐transferases (GSTs) are the superfamily of multifunctional detoxification isoenzymes and play important role cellular signaling. The present article focuses on the role of Cd 2+, Cu 2+, Zn 2+, and Ag + in vitro inhibition of GST. For this purpose, GST was purified from Van Lake fish ( Chalcalburnus tarichii Pallas) gills with 110.664 EU mg ?1 specific activity and 79.6% yield using GSH‐agarose affinity chromatographic method. The metal ions were tested at various concentrations on in vitro GST activity. IC 50 values were found for Cd +2, Cu +2, Zn +2, Ag + as 450.32, 320.25, 1510.13, and 16.43 μM, respectively. K i constants were calculated as 197.05 ± 105.23, 333.10 ± 152.76, 1670.21 ± 665.43, and 0.433 ± 0.251 μM, respectively. Ag + showed better inhibitory effect compared with the other metal ions. The inhibition mechanisms of Cd 2+ and Cu 2+ were non‐competitive, whereas Zn 2+ and Ag + were competitive. Co 2+, Cr 2+, Pb 2+, and Fe 3+ had no inhibitory activity on GST. 相似文献
20.
The extracellular phytase in the supernatant of cell culture of the marine yeast Kodamaea ohmeri BG3 was purified to homogeneity with a 7.2-fold increase in specific phytase activity as compared to that in the supernatant
by ammonium sulfate fractionation, gel filtration chromatography (Sephadex™ G-75), and anion-exchange chromatography (DEAE
Sepharose Fast Flow Anion-Exchange). According to the data from sodium dodecyl sulfate-polyacrylamide gel electrophoresis,
the molecular mass of the purified enzyme was estimated to be 98.2 kDa while the molecular mass of the purified enzyme was
estimated to be 92.9 kDa and the enzyme was shown to be a monomer according to the results of gel filtration chromatography.
The optimal pH and temperature of the purified enzyme were 5.0 and 65°C, respectively. The enzyme was stimulated by Mn 2+, Ca 2+, K +, Li +, Na +, Ba 2+, Mg 2+ and Co 2+ (at a concentrations of 5.0 mM), but it was inhibited by Cu 2+, Hg 2+, Fe 2+, Fe 3+, Ag +, and Zn 2+ (at a concentration of 5.0 mM). The enzyme was also inhibited by phenylmethylsulfonyl fluoride (PMSF), iodoacetic acid (at
a concentration of 1.0 mM), and phenylgloxal hydrate (at a concentration of 5.0 mM), and not inhibited by EDTA and 1,10-phenanthroline
(at concentrations of 1.0 mM and 5.0 mM). The K
m, V
max, and K
cat values of the purified enzyme for phytate were 1.45 mM, 0.083 μmol/ml · min, and 0.93 s -1, respectively. 相似文献
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