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1.
Mammalian cells contain a pool of iron that is not strongly bound to proteins, which can be detected with fluorescent chelating
probes. The cellular ligands of this biologically important “chelatable”, “labile” or “transit” iron are not known. Proposed
ligands are problematic, because they are saturated by magnesium under cellular conditions and/or because they are not “safe”,
i.e. they allow iron to catalyse hydroxyl radical formation. Among small cellular molecules, certain inositol phosphates (Ins Ps) excel at complexing Fe 3+ in such a “safe” manner in vitro. However, we previously calculated that the most abundant Ins P, inositol hexakisphosphate, cannot interact with Fe 3+ in the presence of cellular concentrations of Mg 2+. In this work, we study the metal complexation behaviour of inositol 1,2,3-trisphosphate [Ins(1,2,3) P
3], a cellular constituent of unknown function and the simplest Ins P to display high-affinity, “safe”, iron complexation. We report thermodynamic constants for the interaction of Ins(1,2,3) P
3 with Na +, K +, Mg 2+, Ca 2+, Cu 2+, Fe 2+ and Fe 3+. Our calculations indicate that Ins(1,2,3) P
3 can be expected to complex all available Fe 3+ in a quantitative, 1:1 reaction, both in cytosol/nucleus and in acidic compartments, in which an important labile iron subpool
is thought to exist. In addition, we calculate that the fluorescent iron probe calcein would strip Fe 3+ from Ins(1,2,3) P
3 under cellular conditions, and hence labile iron detected using this probe may include iron bound to Ins(1,2,3) P
3. Therefore Ins(1,2,3) P
3 is the first viable proposal for a transit iron ligand.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
2.
In this study, the applicability of three modelling approaches was determined in an effort to describe complex relationships
between process parameters and to predict the performance of an integrated process, which consisted of a fluidized bed bioreactor
for Fe 3+ regeneration and a gravity settler for precipitative iron removal. Self-organizing maps were used to visually evaluate the
associations between variables prior to the comparison of two different modelling methods, the multiple regression modelling
and artificial neural network (ANN) modelling, for predicting Fe(III) precipitation. With the ANN model, an excellent match
between the predicted and measured data was obtained ( R
2 = 0.97). The best-fitting regression model also gave a good fit ( R
2 = 0.87). This study demonstrates that ANNs and regression models are robust tools for predicting iron precipitation in the
integrated process and can thus be used in the management of such systems. 相似文献
3.
Ferric binding protein, Fbp, serves an essential biological function in shuttling naked (hydrated) Fe 3+ across the periplasmic space of many Gram-negative bacteria. In this process, iron must be released at the cytoplasmic membrane to a permease. How iron is released from Fbp has yet to be resolved. Consequently, understanding the dynamics of iron release from Fbp is of both biological and chemical interest. Fbp requires an exogenous anion, e.g. phosphate when isolated from cell lysates, for tight iron sequestration. To address the role of exogenous anion identity and lability on Fe aq
3+ dissociation from Fbp, the kinetics of PO 4
3– exchange in Fe 3+
nFbp(PO 4) ( nFbp=recombinant Fbp from Neisseria meningitidis) were investigated by dynamic 31P NMR and the kinetics of Fe 3+ dissociation from Fe 3+
nFbp(X) (X=PO 4
3–, citrate anion) were investigated by stopped-flow pH-jump measurements. We justify the use of non-physiological low-pH conditions because a high [H +] will drive the Fe aq
3+ dissociation reaction to completion without using competing chelators, whose presence may complicate or influence the dissociation mechanism. For perspective, these studies of nFbp (which has been referred to as a bacterial transferrin) are compared to new and previously published kinetic and thermodynamic data for mammalian transferrin. Significantly, we address the lability of the Fe 3+ coordination shell in nFbp, Fe 3+
nFbp(X) (X=PO 4
3–, citrate), with respect to exogenous anion (X
n–) exchange and dissociation, and ultimately complete dissociation of the protein to yield naked (hydrated) Fe aq
3+. These findings are a first step in understanding the process of iron donation to the bacterial permease for transport across the cytoplasmic membrane.Electronic Supplementary Material Supplementary material is available in the online version of this article at . Abbreviations DTPP
diethylenetriaminepenta(methylenephosphonic acid)
- Fbp
ferric binding protein
- H 3cit
citric acid
-
hFbp
Fbp from Haemophilus influenzae
- H 2ox
oxalic acid
-
hTf
human serum transferrin
- 3,4-LICAMS
N, N, N-tris(5-sulfo-2,3-dihydroxybenzoyl)-1,5,10-triazadecane
-
nFbp
recombinant Fbp from Neisseria meningitidis
- NTA
nitrilotriacetic acid
- TRENSOX
tris[2-aminoethyl(8-hydroxyquinoline-5-sulfonato-7-carbonyl)]amine 相似文献
4.
PVA-cryogels entrapping about 10 9 cells of Acidithiobacillus ferrooxidans per ml of gel were prepared by freezing-thawing procedure, and the biooxidation of Fe 2+ by immobilized cells was investigated in a 0.365 l packed-bed bioreactor. Fe 2+ oxidation fits a plug-flow reaction model well. A maximum oxidation rate of 3.1 g Fe 2+ l –1 h –1 was achieved at the dilution rate of 0.4 h –1 or higher, while no obvious precipitate was determined at this time. In addition, cell-immobilized PVA-cryogels packed in bioreactor maintained their oxidative ability for more than two months under non-sterile conditions.
Nomenclature:
C
A0 – Concentration of Fe 2+ in feed stream (g l –1) C
A – Concentration of Fe 2 + in outlet stream (g l – 1) D – Dilution rate of the packed-bed bioreactor (h –1) F – Volumetric flow rate of iron solution (l h –1) F
A0 – Mass flow rate of Fe 2+ in the feed stream (g h –1) K – Kinetic constant (l l –1 h –1) r
A – Oxidation rate of Fe 2+ (g l –1 h –1) V – Volume of packed-bed bioreactor (l) X
A – Conversion ratio of Fe 2+ (%) 相似文献
5.
Summary
Geotrichum candidum (isolate 1–9) pathogenic on citrus fruits, appears to lack siderophore production. Iron uptake by G. candidum is mediated by two distinct iron-regulated, energy-and temperature-dependent transport systems that require sulfhydryl groups. One system exhibits specificity for either ferric or ferrous iron, whereas the other exhibits specificity for ferrioxamine-B-mediated iron uptake and presumably other hydroxamate siderophores. Radioactive iron uptake from 59FeCl 3 showed an optimum at pH 6 and 35° C, and Michaelis-Menten kinetics (apparent K
m = 3 m, V
max = 0.054 nmol · mg –1 · min –1). The maximal rate of Fe 2+ uptake was higher than Fe 3+ ( V
max = 0.25 nmol · mg –1 · min –1) but the K
m was identical. Reduction of ferric to ferrous iron prior to transport could not be detected. The ferrioxamine B system exhibits an optimum at pH 6 and 40° C and saturation kinetics ( K
m = 2 M, V
max = 0.22 nmol · mg –1 · min –1). The two systems were distinguished as two separate entities by negative reciprocal competition, and on the basis of differential response to temperature and phenazine methosulfate. Mössbauer studies revealed that cells fed with either 57FeCl 3 or 57FeCl 2 accumulated unknown ferric and ferrous binding metabolites. 相似文献
6.
Kinetic data of ferrous iron oxidation by Thionacillus ferrooxidans were determined. The aim was to remove H 2S (<0.5 ppm) from waste gas by a process proposed earlier. Kinetic data necessary for industrial scale-up were investigated in a chemostat airlift reactor (dilution rate 0.02–0.12 h –1; pH 1.3). Due to the low pH, ferric iron precipitation and wall growth could be avoided. The maximum ferrous iron oxidation rate of submersed bacteria was 0.77 g 1 –1 h –1, the maximum specific growth rate about 0.12 h –1 and the yield coefficient was found to be 0.007 g g –1 Fe 2+. The specific O 2 demand of an exponentially growing, ironoxidizing batch culture was 1.33 mg O 2 mg –1 biomass h –1. The results indicate that a pH of 1.3 has no negative influence on the kinetics of iron oxidation and growth.
Correspondence to: W. Schäfer-Treffenfeldt 相似文献
7.
This study investigates the impacts of influent ammonium concentrations on the microbial community in immobilized heterotrophic ammonium removal system. Klebsiella sp. FC61, the immobilized species, has the ability to perform simultaneous ammonium removal and Fe3+ reduction. It was found that average ammonium removal rate decreased from 0.308 to 0.157 mg/L/h, as the influent NH4
+-N was reduced from 20 to 10 mg/L. Meanwhile, at a total Fe3+ concentration of 20 mg/L, the average Fe3+ reduction removal efficiency and rate decreased from 44.61% and 0.18 mg/L/h, to 27.10% and 0.11 mg/L/h, respectively. High-throughput sequencing was used to observe microbial communities in bioreactor Samples B1, B2, and B3, after exposure to different influent NH4
+-N conditions. Results show that higher influent NH4
+-N concentrations increased microbial richness and diversity and that Klebsiella sp. FC61 play a functional role in the simultaneous removal of NH4
+-N and Fe3+ reduction in bioreactor systems. 相似文献
8.
The uptake of 59Fe from FeCl 3, ferric (Fe 3+) citrate (FeCitr) and Fe 3+-EDTA (FeEDTA) was studied in leaf mesophyll of Vigna unguiculata (L.) Walp. Uptake rates decreased in the order FeCl 3>FeCitrFeEDTA, and uptake depended on an obligatory reduction step of Fe 3+ to Fe 2+, after which the ion could be taken up independently of the chelator, citrate. Uptake was strongly increased by photosynthetically active light (>630 nm), and kinetic analysis revealed saturation kinetics with a K
m (FeCitr) of 80–110 M. In the presence of an external Fe 2+ scavenger, bathophenanthroline disulfonate, the mesophyll also reduced external FeCitr with a K
m of approx. 50–60 M. The reduction rates for FeCitr were five-to eightfold higher than necessary for uptake. Purified plasma membranes from leaves revealed an NADH-dependent FeCitr- and FeEDTA-reductase activity, which had a pH optimum of 6.5–6.8 and a K
m of approx. 20 M for NADH. Under anaerobic conditions, a K
m of 130–170 M for ferric chelates was obtained, while in the presence of oxygen a K
m (FeCitr) of approx. 100 M was found. It is concluded that the leaf plasma membrane provides a ferric-chelate-reductase activity, which plays a crucial role in iron uptake of leaf cells. Under in-vivo conditions, however, reactive oxygen species or strong (blue) light may also contribute to the obligatory reduction of Fe 3+ prior to uptake.Abbreviations BPDS
bathophenanthroline disulfonate
- DCMU
3-(3,4 dichlorophenyl)-1,1-dimethyl urea
- FCR
ferricchelate reductase
- FeCitr
Fe 3+-citrate
- FeEDTA
Fe 3+-EDTA
- PM
plasma membrane
This work was supported by the SCIENCE program of the European Community (contract no. SC1000344; P.R.M.). We wish to thank P. Siersma and C. Winter for their cooperation at the Central Isotope Laboratory of the Biological Centre of the University of Groningen. 相似文献
9.
The extreme acid conditions required for scorodite (FeAsO 4·2H 2O) biomineralization (pH below 1.3) are suboptimal for growth of most thermoacidophilic Archaea. With the objective to develop
a continuous process suitable for biomineral production, this research focuses on growth kinetics of thermoacidophilic Archaea
at low pH conditions. Ferrous iron oxidation rates were determined in batch-cultures at pH 1.3 and a temperature of 75°C for
Acidianus sulfidivorans, Metallosphaera prunea and a mixed Sulfolobus culture. Ferrous iron and CO 2 in air were added as sole energy and carbon source. The highest growth rate (0.066 h −1) was found with the mixed Sulfolobus culture. Therefore, this culture was selected for further experiments. Growth was not stimulated by increase of the CO 2 concentration or by addition of sulphur as an additional energy source. In a CSTR operated at the suboptimal pH of 1.1, the
maximum specific growth rate of the mixed culture was 0.022 h −1, with ferrous iron oxidation rates of 1.5 g L −1 d −1. Compared to pH 1.3, growth rates were strongly reduced but the ferrous iron oxidation rate remained unaffected. Influent
ferrous iron concentrations above 6 g L −1 caused instability of Fe 2+ oxidation, probably due to product (Fe 3+) inhibition. Ferric-containing, nano-sized precipitates of K-jarosite were found on the cell surface. Continuous cultivation
stimulated the formation of an exopolysaccharide-like substance. This indicates that biofilm formation may provide a means
of biomass retention. Our findings showed that stable continuous cultivation of a mixed iron-oxidizing culture is feasible
at the extreme conditions required for continuous biomineral formation. 相似文献
10.
We examined nitrate-dependent Fe 2+ oxidation mediated by anaerobic ammonium oxidation (anammox) bacteria. Enrichment cultures of “ Candidatus Brocadia sinica” anaerobically oxidized Fe 2+ and reduced NO 3− to nitrogen gas at rates of 3.7 ± 0.2 and 1.3 ± 0.1 (mean ± standard deviation [SD]) nmol mg protein −1 min −1, respectively (37°C and pH 7.3). This nitrate reduction rate is an order of magnitude lower than the anammox activity of “ Ca. Brocadia sinica” (10 to 75 nmol NH 4+ mg protein −1 min −1). A 15N tracer experiment demonstrated that coupling of nitrate-dependent Fe 2+ oxidation and the anammox reaction was responsible for producing nitrogen gas from NO 3− by “ Ca. Brocadia sinica.” The activities of nitrate-dependent Fe 2+ oxidation were dependent on temperature and pH, and the highest activities were seen at temperatures of 30 to 45°C and pHs ranging from 5.9 to 9.8. The mean half-saturation constant for NO 3− ± SD of “ Ca. Brocadia sinica” was determined to be 51 ± 21 μM. Nitrate-dependent Fe 2+ oxidation was further demonstrated by another anammox bacterium, “ Candidatus Scalindua sp.,” whose rates of Fe 2+ oxidation and NO 3− reduction were 4.7 ± 0.59 and 1.45 ± 0.05 nmol mg protein −1 min −1, respectively (20°C and pH 7.3). Co-occurrence of nitrate-dependent Fe 2+ oxidation and the anammox reaction decreased the molar ratios of consumed NO 2− to consumed NH 4+ (ΔNO 2−/ΔNH 4+) and produced NO 3− to consumed NH 4+ (ΔNO 3−/ΔNH 4+). These reactions are preferable to the application of anammox processes for wastewater treatment. 相似文献
11.
Fe 2+ is oxidized and taken up by ferritin or ápoferritin in the presence of dioxygen. Iodate causes Fe 2+ oxidation and uptake by ferritin, but not by apoferritin. Synthetic iron polymer facilitates Fe 2+ oxidation by either dioxygen or iodate. Nitrilotriacetic acid or iminodiacetic acid facilitate oxidation of Fe 2+ by oxygen but not by iodate. These results support the crystal growth model of ferritin iron uptake, with iron polymer serving as a model for the ferritin core and aminocarboxylic acids mimicking the metal-binding sites of apoferritin. 相似文献
12.
We document the discovery of the first granular iron formation (GIF) of Archaean age and present textural and geochemical results that suggest these formed through microbial iron oxidation. The GIF occurs in the Nconga Formation of the ca. 3.0–2.8 Ga Pongola Supergroup in South Africa and Swaziland. It is interbedded with oxide and silicate facies micritic iron formation (MIF). There is a strong textural control on iron mineralization in the GIF not observed in the associated MIF. The GIF is marked by oncoids with chert cores surrounded by magnetite and calcite rims. These rims show laminated domal textures, similar in appearance to microstromatolites. The GIF is enriched in silica and depleted in Fe relative to the interbedded MIF. Very low Al and trace element contents in the GIF indicate that chemically precipitated chert was reworked above wave base into granules in an environment devoid of siliciclastic input. Microbially mediated iron precipitation resulted in the formation of irregular, domal rims around the chert granules. During storm surges, oncoids were transported and deposited in deeper water environments. Textural features, along with positive δ 56Fe values in magnetite, suggest that iron precipitation occurred through incomplete oxidation of hydrothermal Fe 2+ by iron‐oxidizing bacteria. The initial Fe 3+‐oxyhydroxide precipitates were then post‐depositionally transformed to magnetite. Comparison of the Fe isotope compositions of the oncoidal GIF with those reported for the interbedded deeper water iron formation (IF) illustrates that the Fe 2+ pathways and sources for these units were distinct. It is suggested that the deeper water IF was deposited from the evolved margin of a buoyant Fe 2+aq‐rich hydrothermal plume distal to its source. In contrast, oncolitic magnetite rims of chert granules were sourced from ambient Fe 2+aq‐depleted shallow ocean water beyond the plume. 相似文献
13.
Nitric -oxide reductase (NOR) from Paracoccus denitrificans catalyzes the reduction of nitric oxide (NO) to nitrous oxide (N 2O) (2NO + 2H + + 2e − →N 2O + H 2O) by a poorly understood mechanism. NOR contains two low spin hemes c and b, one high spin heme b3, and a non-heme iron Fe B. Here, we have studied the reaction between fully reduced NOR and NO using the “flow-flash” technique. Fully (four-electron) reduced NOR is capable of two turnovers with NO. Initial binding of NO to reduced heme b3 occurs with a time constant of ∼1 μs at 1.5 m m NO, in agreement with earlier studies. This reaction is [NO]-dependent, ruling out an obligatory binding of NO to Fe B before ligation to heme b3. Oxidation of hemes b and c occurs in a biphasic reaction with rate constants of 50 s −1 and 3 s −1 at 1.5 m m NO and pH 7.5. Interestingly, this oxidation is accelerated as [NO] is lowered; the rate constants are 120 s −1 and 12 s −1 at 75 μ m NO. Protons are taken up from solution concomitantly with oxidation of the low spin hemes, leading to an acceleration at low pH. This effect is, however, counteracted by a larger degree of substrate inhibition at low pH. Our data thus show that substrate inhibition in NOR, previously observed during multiple turnovers, already occurs during a single oxidative cycle. Thus, NO must bind to its inhibitory site before electrons redistribute to the active site. The further implications of our data for the mechanism of NO reduction by NOR are discussed. 相似文献
14.
Transferrin (Tf) is a kind of non-heme β-globulin with two iron ions (Fe 3+)-binding sites. To prove Tf’s physiological functions, Fe 3+-proteins, serum iron contents, and total iron-binding capabilities were tested for Tfs of crucian carps ( Carassius auratus) and sliver carps ( Hypophthalmichthys molitrix). The above results demonstrated that sliver carps shared 1/3 Tf alleles with crucian carps; Tf of crucian carps had stronger
Fe 3+-binding ability and transportation ability in plasma than that of sliver carps. In addition, the results of oxygen consumption
experiments indicated that crucian carps had the higher oxygen utility rate than sliver carps. For acute hypoxia exposure
assay, normoxic gas mixture, hypoxic gas mixture A, and hypoxic gas mixture B were used to induce oxygen-regulated gene expression
of crucian carps in acute hypoxia. The results of quantitative real-time PCR revealed that mRNA levels of Tf gene, Tfr gene
and ATPase gene were down-regulated in acute hypoxia but mRNA level of LDHa gene was up-regulated in acute hypoxia. The results
of crucian carp Tf-cDNA sequence analysis showed that cDNA regions of two Fe 3+-binding sites were T 747–T 1026 and T 1737–A 1884 based on the principle of bioinformatics. The sequence conservation of two Fe 3+-binding sites was higher than that of the other five regions, which were confirmed according to the subregion model of Tf-cDNA
sequence. 相似文献
15.
Morpho-physiological and biochemical responses of Arabidopsis thaliana (accession N1438) to bicarbonate-induced iron deficiency were investigated. Plants were grown in cabinet under controlled
conditions, in a nutrient solution containing 5 μM Fe, added or not with 10 mM NaHCO 3. After 30 days, bicarbonate-treated plants displayed significantly lower biomass, leaf number and leaf surface area as compared
to control plants, and slight yellowing of their younger leaves was observed. Potassium (K +) content was not modified by bicarbonate treatment in roots, whereas it was significantly diminished in shoots. Their content
in ferrous iron (Fe 2+) and in leaf total chlorophylls was noticeably lower than in control plants. Root Fe(III)-chelate reductase and phosphoenolpyruvate
carboxylase (PEPC) activities were significantly enhanced, but leaf ribulose 1.5-bisphosphate carboxylase (Rubisco) activity
was decreased. 相似文献
16.
Plutonium (Pu), a key contaminant at sites associated with the manufacture of nuclear weapons and with nuclear-energy wastes,
can be precipitated to “immobilized” plutonium phases in systems that promote bioreduction. Ferric iron (Fe 3+) is often present in contaminated sites, and its bioreduction to ferrous iron (Fe 2+) may be involved in the reduction of Pu to forms that precipitate. Alternately, Pu can be reduced directly by the bacteria.
Besides Fe, contaminated sites often contain strong complexing ligands, such as nitrilotriacetic acid (NTA). We used biogeochemical
modeling to interpret the experimental fate of Pu in the absence and presence of ferric iron (Fe 3+) and NTA under anaerobic conditions. In all cases, Shewanella alga BrY ( S. alga) reduced Pu(V)(PuO 2
+) to Pu(III), and experimental evidence indicates that Pu(III) precipitated as PuPO 4(am). In the absence of Fe 3+ and NTA, reduction of PuO 2
+ was directly biotic, but modeling simulations support that PuO 2
+ reduction in the presence of Fe 3+ and NTA was due to an abiotic stepwise reduction of PuO 2
+ to Pu 4+, followed by reduction of Pu 4+ to Pu 3+, both through biogenically produced Fe 2+. This means that PuO 2
+ reduction was slowed by first having Fe 3+ reduced to Fe 2+. Modeling results also show that the degree of PuPO 4(am) precipitation depends on the NTA concentration. While precipitation out-competes complexation when NTA is present at the
same or lower concentration than Pu, excess NTA can prevent precipitation of PuPO 4(am). 相似文献
17.
Iron autoxidation in Mops and Hepes buffers is characterized by a lag phase that becomes shorter with increasing FeCl 2 concentration and pH. During iron oxidation in these buffers a yellow colour develops in the solution. When the reaction is conducted in the presence of nitro blue tetrazolium (NBT), blue formazan is formed. Of the many OH' scavengers tested, mannitol and sorbitol are most effective in inhibiting Fe 2+ oxidation, yellow colour development and NBT reduction. Some inhibition was also noted with catalase. The iron product of the oxidative reaction differs from Fe 3+ in its absorption spectrum and its low reactivity with thiocyanate. Similar results are obtained when iron autoxidation is studied in unbuffered solutions brought to alkaline pH with NaOH. In phosphate buffer, no lag phase is evident and the absorption spectrum of the final solution is identical to that of Fe 3+ in this buffer. The iron product reacts immediately with thiocyanate. When iron oxidation is conducted in the presence of NBT the formation of formazan is almost undetectable. Of the many compounds tested only catalase inhibits iron autoxidation in this buffer. The sequence of reactions leading to iron autoxidation in Good-type buffers 1 thus resembles that occurring in unbuffered solutions brought to alkaline pH with NaOH and greatly differs from that occurring in phosphate buffer. These results are in agreement with the observation that these buffers have very low affinity for iron. 1 The data presented define experimental conditions where Fe 2+ is substantially stable for a considerable length of time in Mops buffer. 相似文献
18.
Bacterial ferritin from Azotobacter vinelandii (AvBF o has a function in H 2 uptake. The Fe 3+ reduction on the surface of the iron core from AvBF o is accompanied simultaneously by H 2 uptake, with a maximum activity of H 2 uptake of 450 H 2/AvBF o. A reduction potential of –402 mV for iron reduction on the surface of the core is found. A shift to the red the protein absorbance peaks ranging from 280 to 290 nm is observed between pH5 and 9 under 100% H 2 reduction. The reduction potential for iron release becomes negative at a rate of 0.025 mV/Fe 2+ released. The kinetics of iron release on the surface of the core is a first-order reaction. 相似文献
19.
The kinetics for complete iron release showing biphasic behavior from pig spleen ferritin-Fe (PSFF) was measured by spectrophotometry. The native core within the PSFF shell consisted of 1682 hydroxide Fe 3+ and 13 phosphate molecules. Inhibition kinetics for complete iron release was measure by differential spectrophotometry in the presence of phosphate; the process was clearly divided into two phases involving a first-order reaction at an increasing rate of 46.5 Fe 3+/PSFF/min on the surface of the iron core and a zero-order reaction at a decreasing rate of 6.67 Fe 3+/PSFF/min inside the core. The kinetic equation [ C(PSFF-Fe 3+) max – C(PSFF-Fe 3+)
t
] 1/2 = T
max – T
t gives the transition time between the two rates and represents the complex kinetic characteristics. The rate was directly accelerated twofold by a mixed reducer of dithionite and ascorbic acid. These results suggest that the channel of the PSFF shell may carry out multiple functions for iron metabolism and storage and that the phosphate strongly affects the rate of iron release. 相似文献
20.
Background
Photorhabdus are Gram negative bacteria that are pathogenic to insect larvae whilst also having a mutualistic interaction with nematodes
from the family Heterorhabditis. Iron is an essential nutrient and bacteria have different mechanisms for obtaining both the ferrous (Fe 2+) and ferric (Fe 3+) forms of this metal from their environments. In this study we were interested in analyzing the role of Fe 3+ and Fe 2+ iron uptake systems in the ability of Photorhabdus to interact with its invertebrate hosts. 相似文献
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