Activity Of Mg Research Articles

Study of Na+/K+-ATPase and Components of the Ca2+-transporting System in Myocardium under Experimental Prediabetes and Type 1 Diabetes in Rats

One of the complications of diabetes mellitus (DM) is diabetic cardiomyopathy (DCM), the molecular mechanisms of pathogenesis of which have not been fully studied. Previously, the involvement of Na+/K+-ATPase and components of the Ca2+ transport system in cardiomyocytes in the development of DCM was shown. The aim of the work was to study the expression and activity of Na+/K+-ATPase and Ca2+-ATPase (SERCA2) in the myocardium of male Wistar rats in a model of streptozotocin (STZ)-induced prediabetes and overt type 1 diabetes (T1DM). STZ was administered at once i. p. in dose of 30–35 mg/kg. Rats with glucose levels above 11 mM were considered diabetic (STZ-D1 group), and those with moderate hyperglycemia were considered prediabetic (STZ-preD1 group). The activity of Na+/K+-ATPase and Ca2+-ATPase was determined (by the rate of release of inorganic phosphate, Pi), and the expression of the genes α1- and α2-isoforms of Na+/K+-ATPase, SERCA2 and Kir6.1, Kv7.1 and Kv2.1 potassium channels. In the control (C) group, the activity of Mg2+-dependent ATPase (α1- and α2-isoforms of Na+/K+-ATPase), sensitive to 1 mM ouabain, was 6.03±0.6 mmol Pi/g/h. In the STZ-D1 and STZ-preD1 groups, Na+/K+-ATPase activity did not differ from group C. The level of gene expression of α1- and α2- subunits of Na+/K+-ATPase in the STZ-D1 group decreased by more than 45%, then both in the STZ-preD1 group increased by 64 and 81%, which may indicate a high sensitivity of expression to insulinopenia. The activity of Ca2+-ATPase and the expression of the SERCA2 gene did not differ between the groups – probably, the 4-week period after STZ administration is not sufficient for the development of Ca2+-ATPase deficiency in the rat heart. The level of expression of the genes of the potassium channel subtypes Kv2.1, Kir6.1 and Kv7.1 increased in the STZ-preD1 group, which may indicate a certain contribution of the studied potassium channel subtypes to the adaptation mechanism to moderate hyperglycemia.

Insight into enhanced adsorption of Congo red by petal-like MgAl2O4: effect of dehydroxylation

This paper reports a facile treatment to enhance the capacity of petal-like MgAl2O4 for Congo red (CR) adsorption. The influence of dehydroxylation treatment on the adsorption performance of petal-like MgAl2O4is investigated. FT-IR, XPS, TG, XRD and FE-SEM are employed to analyze the differences between samples without and with dehydroxylation. Mechanism on the adsorption capacity improvement of CR by MgAl2O4 after dehydroxylation is investigated systematically. Results show that the adsorption process conforms well to the pseudo-second-order kinetic model and Langmuir isotherm model. The adsorption mechanism study shows that the adsorption of CR on petal-like MgAl2O4is mainly due to chemisorption including Lewis acid-base interaction and electrostatic attraction. It is observed that the maximum adsorption capacity of petal-like MgAl2O4after dehydroxylation reaches 3264.54 mg/g, much higher than sample without dehydroxylation (591.72 mg/g). Most Lewis acid sites of petal-like MgAl2O4 (Mg2+ and Al3+) without dehydroxylation process are occupied by hydroxyl groups. It is not conductive to combine with NH2- and -SO32- in CR molecular, resulting in the deterioration of adsorption performance. The activity of Mg2+ and Al3+ in MgAl2O4 can be recovered greatly after the removal of hydroxyl groups, and it is favorable to the adsorption between MgAl2O4 and CR.

Engineering Infrequent DNA Nicking Endonuclease by Fusion of a BamHI Cleavage-Deficient Mutant and a DNA Nicking Domain.

Strand-specific DNA nicking endonucleases (NEases) typically nick 3–7 bp sites. Our goal is to engineer infrequent NEase with a >8 bp recognition sequence. A BamHI catalytic-deficient mutant D94N/E113K was constructed, purified, and shown to bind and protect the GGATCC site from BamHI restriction. The mutant was fused to a 76-amino acid (aa) DNA nicking domain of phage Gamma HNH (gHNH) NEase. The chimeric enzyme was purified, and it was shown to nick downstream of a composite site 5′ GGATCC-N(4-6)-AC↑CGR 3′ (R, A, or G) or to nick both sides of BamHI site at the composite site 5′ CCG↓GT-N5-GGATCC-N5-AC↑CGG 3′ (the down arrow ↓ indicates the strand shown is nicked; the up arrow↑indicates the bottom strand is nicked). Due to the attenuated activity of the small nicking domain, the fusion nickase is active in the presence of Mn2+ or Ni2+, and it has low activity in Mg2+ buffer. This work provided a proof-of-concept experiment in which a chimeric NEase could be engineered utilizing the binding specificity of a Type II restriction endonucleases (REases) in fusion with a nicking domain to generate infrequent nickase, which bridges the gap between natural REases and homing endonucleases. The engineered chimeric NEase provided a framework for further optimization in molecular diagnostic applications.

Protective Effect of Ipomoea biloba on Myocardial Antioxidant Status in Isoproterenol Induced Myocardial Infarction Male Albino Rats

The protective effect of ethanolic leaf extract of Ipomoea biloba in isoproterenol (ISO)-induced cardiotoxicity and the antioxidant activity involved in this protection were investigated in rats. Myocardial infraction was produced in rats with 20 mg/kg b.wt of ISO administered subcutaneously twice at an interval of 24 h. Effect of EEIB oral treatment for 28 days at two doses (100 mg and 200 mg/kg body weight) was evaluated against ISO – induced cardiac necrosis. Level of enzymatic (SOD, CAT, GPx and GST), non-enzymatic (GSH, Vitamin C and E) and of membrane bound ATPases (Na+K+ATPase, Mg2+ATPase and Ca2+ATPase) were assayed in heart homogenate. Significant myocardial infarction, depletion of endogenous antioxidants enzymatic and non-enzymatic were observed in ISO-treated animals when compared with the normal animals. Rats induced with ISO, showed a significant (P<0.05), decrease in the activities of GSH, Vitamin C and Eon comparison with normal rats. EEIB elicited a significant cardioprotective activity by elevated the levels of GSH, SOD, CAT, GPx and GR. A significant decrease in the activity of Na+/K+ ATPase and a corresponding increase in the activities of Ca2+ ATPase and Mg2+ ATPase were observed in isoproterenol induced rats when compared to normal control rats. Pretreatment with EEIB was able to efficiently prevent the increase in activity of Mg2+ ATPase and maintain the activities of Na+ /K+ ATPase and Ca2+ ATPase at near normality. There is no significant difference between the control and plant alone treated rats. The aim of this investigation is to evaluate the antioxidant effects on the main cardioprotective activity of ethanolic leaf extract Ipomoea biloba.

Cellular Adaptations to Cytoplasmic Mg2+ Limitation.

Mg2+ is the most abundant divalent cation in living cells. It is essential for charge neutralization, macromolecule stabilization, and the assembly and activity of ribosomes and as a cofactor for enzymatic reactions. When experiencing low cytoplasmic Mg2+, bacteria adopt two main strategies: They increase the abundance and activity of Mg2+ importers and decrease the abundance of Mg2+-chelating ATP and rRNA. These changes reduce regulated proteolysis by ATP-dependent proteases and protein synthesis in a systemic fashion. In many bacterial species, the transcriptional regulator PhoP controls expression of proteins mediating these changes. The 5' leader region of some mRNAs responds to low cytoplasmic Mg2+ or to disruptions in translation of open reading frames in the leader regions by furthering expression of the associated coding regions, which specify proteins mediating survival when the cytoplasmic Mg2+ concentration is low. Microbial species often utilize similar adaptation strategies to cope with low cytoplasmic Mg2+ despite relying on different genes to do so.

Delaying Broccoli Floret Yellowing by Phytosulfokine α Application During Cold Storage.

During postharvest life, broccoli suffers from floret yellowing confining its economic and nutritional value. The objective of the present study was to explore the mechanisms employed by phytosulfokine α (PSKα) at 150 nM for delaying floret yellowing in broccoli during storage at 4°C for 28 days. Our results showed that the higher endogenous accumulation of hydrogen sulfide (H2S) resulting from the higher gene expression and activities of l-cysteine desulfhydrase (LCD) and d-cysteine desulfhydrase (DCD) in broccoli floret treated with 150 nM PSKα may serve as an endogenous signaling molecule for delaying senescence. Moreover, the suppressed ethylene biosynthesis in broccoli floret treated with 150 nM PSKα might be ascribed to lower gene expression and activities of ACC synthase (ACS) and ACC oxidase (ACO). Furthermore, lower gene expression and activities of Mg2+ dechelatase (MDC), pheophytinase (PPH), and pheophorbide a oxygenase (PaO) might be the reasons for the higher accumulation of chlorophyll in broccoli floret treated with 150 nM PSKα. Based on our findings, exogenous PSKα application could be employed as signaling bioactive hormone for retarding floret yellowing of broccoli during storage at 4°C for 28 days.

Hyperdiverse archaea near life limits at the polyextreme geothermal Dallol area.

Microbial life has adapted to various individual extreme conditions; yet, organisms simultaneously adapted to very low pH, high salt and high temperature are unknown. We combined environmental 16S/18S rRNA-gene metabarcoding, cultural approaches, fluorescence-activated cell sorting, scanning electron microscopy and chemical analyses to study samples along such unique polyextreme gradients in the Dallol-Danakil area (Ethiopia). We identify two physicochemical barriers to life in the presence of surface liquid water defined by: i) high chaotropicity-low water activity in Mg2+/Ca2+-dominated brines and ii) hyperacidity-salt combinations (pH~0/NaCl-dominated salt-saturation). When detected, life was dominated by highly diverse ultrasmall archaea widely distributed across phyla with and without previously known halophilic members. We hypothesize that high cytoplasmic K+-level was an original archaeal adaptation to hyperthermophily, subsequently exapted during multiple transitions to extreme halophily. We detect active silica encrustment/fossilization of cells but also abiotic biomorphs of varied chemistry. Our work helps circumscribing habitability and calls for cautionary interpretations of morphological biosignatures on Earth and beyond.

ATPase Activity in Red-Blood and Muscle Tissue Cells in Sheep

The objective of the survey is to identify the specificities in the functions of ATPase enzyme systems in blood and the longest back muscle in sheep of two breeds and different ages. Lambs and wethers of Texel and Kuibyshev breeds sampled on the analog principle are the subject of the survey according to the current animal-keeping and feeding standards developed by the Ernst All-Russia Research Institute for Animal Husbandry. It has been ascertained that the activities of Mg2+, Na+, K+-ATPase, Mg2+-ATase, and Na+, K+-ATPase in the lamb’s red-blood cell membranes are determined by the age at high significance levels (P < 0.001) of 99.45, 99.41, and 98.46%, respectively, while their activities in the wethers’ longest back muscle are determined by the age at the levels of 81.09, 85.16, and 83.21%, respectively. The correlation analysis has proven the effects of age on the ATPase activity in the membranes of the red blood cells and the longest back muscle сells. With respect to red blood cells, the correlation is negative, while the muscle tissue is found to have a positive correlation. No significant effect of the breed specificity on the activities of Mg2+, Na+, K+-ATPase, Mg2+-ATPase, and Na+, K+-ATPase in the red-blood and muscle tissue cells was identified.

ATFpase the activity of red blood cells and muscle tissue of sheep

The aim of the research was to establish the functioning of the ATPase enzyme systems of the blood and the longest back muscle of sheep of various breeds and ages. The object of the study was selected according to the principle of analogs of lambs and valukha of Texel and Kuibyshev breed, the feeding conditions and content of which corresponded to the current standards developed by the survival permit. It was established that the activity of Mg2 +, Na +, K + -, Mg2 + - and Na +, K + -ATPases in the membrane of erythrocytes of lambs is determined by age with a high degree of confidence (P 0.001), respectively, at 99.45; 99.41 and 98.46%; the activity of Mg2 +, Na +, K + -, Mg2 + - and Na +, K + -ATPases of the longest back muscle of the valuchs, respectively, by 81.09%; 85.16 and 83.21%. The correlation analysis carried out by the authors proved the effect on the ATPase activity of the erythrocyte membrane and the longest back muscle age; moreover, in the case of erythrocytes, the correlation is negative, in the case of muscle tissue, it is positive. No significant influence of animal species on the activity of Mg2 +, Na +, K + -, Mg2 + - and Na +, K + -ATPases of the erythrocyte membrane and sheep muscle was not found.

Triplex DNA formation-mediated strand displacement reaction for highly sensitive fluorescent detection of melamine

Since melamine is a strong hazard to human health, the development of new methods for highly sensitive detection of melamine is highly desirable. Herein, a novel fluorescent biosensing strategy was designed for sensitive and selective melamine assay based on the recognition ability of abasic (AP) site in triplex towards melamine and signal amplification by Mg2+-dependent DNAzyme. In this strategy, the melamine-induced formation of triplex DNA was employed to trigger the strand displacement reaction (SDR). The SDR process converted the specific target recognition into the release and activation of Mg2+-dependent DNAzyme, which could catalyze the cleavage of fluorophore/quencher labeled DNA substrate (FQ), resulting in a significantly increased fluorescent signal. Under the optimal conditions, the fluorescent signal has a linear relationship with the logarithm of the melamine concentration in a wide range of 0.005–50 μM. The detection limit was estimated to be 0.9 nM (0.1ppb), which is sufficiently sensitive for practical application. Furthermore, this strategy exhibits high selectivity against other potential interfering substances, and the practical application of this strategy for milk samples reveals that the proposed strategy works well for melamine assay in real samples. Therefore, this strategy presents a new method for the sensitive melamine assay and holds great promise for sensing applications in the environment and the food safety field.

Engineering nicking enzymes that preferentially nick 5-methylcytosine-modified DNA

N.ϕGamma is a strand-specific and site-specific DNA nicking enzyme (YCG↓GT or AC↑CGR). Here we describe the isolation of single and double mutants of N.ϕGamma with attenuated activity. The nicking domains (NDs) of E59A and 11 double mutants were fused to the 5mCG-binding domain of MBD2 and generated fusion enzymes that preferentially nick 5mCG-modified DNA. The CG dinucleotide can be modified by C5 methyltransferases (MTases) such as M.SssI, M.HhaI or M.HpaII to create composite sites AC↑YGG N(8–15) 5mCG. We also constructed a fusion enzyme 2xMBD2-ND(N.BceSVIII) targeting more frequent composite sites AS↑YS N(5–12) 5mCG in Mn2+ buffer. 5mCG-dependent nicking requires special digestion conditions in high salt (0.3 M KCl) or in Ni2+ buffer. The fusion enzyme can be used to nick and label 5mCG-modified plasmid and genomic DNAs with fluorescently labeled Cy3-dUTP and potentially be useful for diagnostic applications, DNA sequencing and optical mapping of epigenetic markers. The importance of the predicted catalytic residues D89, H90, N106 and H115 in N.ϕGamma was confirmed by mutagenesis. We found that the wild-type enzyme N.ϕGamma prefers to nick 5mCG-modified DNA in Ni2+ buffer even though the nicking activity is sub-optimal compared to the activity in Mg2+ buffer.

Carnitine modulates crucial myocardial adenosine triphosphatases and acetylcholinesterase enzyme activities in choline-deprived rats

Choline is an essential nutrient, and choline deficiency has been associated with cardiovascular morbidity. Choline is also the precursor of acetylcholine (cholinergic component of the heart's autonomic nervous system), whose levels are regulated by acetylcholinesterase (AChE). Cardiac contraction-relaxation cycles depend on ion gradients established by pumps like the adenosine triphosphatases (ATPases) Na(+)/K(+)-ATPase and Mg(2+)-ATPase. This study aimed to investigate the impact of dietary choline deprivation on the activity of rat myocardial AChE (cholinergic marker), Na(+)/K(+)-ATPase, and Mg(2+)-ATPase, and the possible effects of carnitine supplementation (carnitine, structurally relevant to choline, is used as an adjunct in treating cardiac diseases). Adult male albino Wistar rats were distributed among 4 groups, and were fed a standard or choline-deficient diet for one month with or without carnitine in their drinking water (0.15% w/v). The enzyme activities were determined spectrophotometrically in the myocardium homogenate. Choline deficiency seems to affect the activity of the aforementioned parameters, but only the combination of choline deprivation and carnitine supplementation increased myocardial Na(+)/K(+)-ATPase activity along with a concomitant decrease in the activities of Mg(2+)-ATPase and AChE. The results suggest that carnitine, in the setting of choline deficiency, modulates cholinergic myocardial neurotransmission and the ATPase activity in favour of cardiac work efficiency.

Interactive effects of cadmium and acid rain on photosynthetic light reaction in soybean seedlings

Interactive effects of cadmium (Cd2+) and acid rain on photosynthetic light reaction in soybean seedlings were investigated under hydroponic conditions. Single treatment with Cd2+ or acid rain and the combined treatment decreased the content of chlorophyll, Hill reaction rate, the activity of Mg2+-ATPase, maximal photochemical efficiency and maximal quantum yield, increased initial fluorescence and damaged the chloroplast structure in soybean seedlings. In the combined treatment, the change in the photosynthetic parameters and the damage of chloroplast structure were stronger than those of any single pollution. Meanwhile, Cd2+ and acid rain had the interactive effects on the test indices in soybean seedlings. The results indicated that the combined pollution of Cd2+ and acid rain aggravated the toxic effect of the single pollution of Cd2+ or acid rain on the photosynthetic parameters due to the serious damage to the chloroplast structure.

Effects of Prolactin and Bromocriptine on Physiological Status of Testis of the Musk Shrew (Suncus murinus L.)/Der Einfluß von Prolaktin und Bromocriptin auf den physiologischen Status des Hodens der Moschusspitzmaus (Suncus Murinus L.)

This investigation was undertaken to study the effects of prolactin and bromocriptine on the testis of the musk shrew. None of these treatments had any effect on the weight of testis or on the accessory sex organs. Treatment of prolactin or bromocriptine failed to induce any change in esterified and free cholesterol content of the testis. No significant alterations were also recorded in the levels of macromolecules and in the levels of enzymes of the testis and the prostate gland. On the other hand, bromocriptine treatment resulted in an increase in the activity of Mg2+-ATPase and phospholipid:DNA ratio of the testis with a concomitant decrease in its DNA content. The absence of any change in the content of fructose in the ampullary gland, in the activity of beta-glucuronidase of the kidney, in cholesterol content of the testis, in diameters of seminiferous tubule and Leydig cell nucleus, in activities of acid phosphatase and beta-glucuronidase of the testis and in the weight of accessory sex organs of prolactin and bromocriptine treated musk shrews suggests that prolactin does not play a significant role in regulating the testicular function of the musk shrew.

The influence of hypothalamic proline-rich polypeptide on ATP-phosphohydrolase activity in rat brain mitochondria during epileptiform seizures induced by pentylenetetrazole

We have studied the shifts in the activity of Mg2+-, Ca2+-, and HCO3−-dependent ATPases in brain mitochondria of white rats during epileptiform seizures (ES) induced by pentylenetetrazole. Inhibition of the catalytic activity of Mg2+-, Ca2+-, and HCO3−-dependent ATPases was observed during ES. However, a preliminary intraperitoneal injection of proline-rich polypeptide (PRP) restored the activity of the investigated enzymes after ES to the control level. It is possible to assume that PRP has a protective effect on the body intoxication caused by pentylenetetrazole.

Magnesium-PVC Membrane Sensor Based on 4,5-Bis(Benzoylthio)-1,3-Dithiole-2-Thione

This report describes an attempt to develop potentiometric Mg2+ sensors based on a liquid polymeric membrane. Membrane incorporating 4,5-Bis(benzoylthio)-1,3- dithiole-2-thione (Bz2dmit) as ionophore, with composition Bz2 dmit:NaTPB:NB:PVC in the ratio 2.5:2.5:65:30 (w/w), exhibits the best result for potentiometric sensing of Mg2+ ions. The proposed electrode, based on Bz2 dmitwith nitrobenzene (NB) as a solvent mediator in a polyvinyl chloride (PVC) membrane matrix, exhibited a near-Nernstian response to Mg2+ in the concentration range of 1.0 × 10−5 to 1.0 × 10−1 M, with a slope of 29.2 mV per decade of activity of Mg2+. The lower limit of detection was 1.0 × 10−5 M. This sensor showed high selectivity with respect to alkaline, alkaline earth, transition, and heavy metal ions, except for Sr2+, and could be used over a pH range of 3.5–9.0. It can be used for at least 2 mo without considerable divergence in potentials and has a relatively fast response of <10 s. It was applied successfully as an indicator electrode in potentiometric titration of Mg2+ ions with EDTA.

Glutamate Transporters Regulate Extrasynaptic NMDA Receptor Modulation of Kv2.1 Potassium Channels

Delayed-rectifier Kv2.1 potassium channels regulate somatodendritic excitability during periods of repetitive, high-frequency activity. Recent evidence suggests that Kv2.1 channel modulation is linked to glutamatergic neurotransmission. Because NMDA-type glutamate receptors are critical regulators of synaptic plasticity, we investigated NMDA receptor modulation of Kv2.1 channels in rodent hippocampus and cortex. Bath application of NMDA potently unclustered and dephosphorylated Kv2.1 and produced a hyperpolarizing shift in voltage-dependent activation of voltage-sensitive potassium currents (I(K)). In contrast, driving synaptic activity in Mg2+-free media to hyperactivate synaptic NMDA receptors had no effect on Kv2.1 channels, and moderate pentylenetetrazole-induced seizure activity in adult mice did not dephosphorylate hippocampal Kv2.1 channels. Selective activation of extrasynaptic NMDA receptors unclustered and dephosphorylated Kv2.1 channels and produced a hyperpolarizing shift in neuronal I(K). In addition, inhibition of glutamate uptake rapidly activated NMDA receptors and dephosphorylated Kv2.1 channels. These observations demonstrate that regulation of intrinsic neuronal activity by Kv2.1 is coupled to extrasynaptic but not synaptic NMDA receptors. These data support a novel mechanism for glutamate transporters in regulation of neuronal excitability and plasticity through extrasynaptic NMDA receptor modulation of Kv2.1 channels.

Antioxidation and ATPase activity in the gill of mud crab Scylla serrata under cold stress

Mud crab (Scylla serrata) is an important commercial crustacean in China. An experiment was designed to study the effect of cold stress on S. serrata. After a one-week adaptation at 28°C, the temperature is suddenly reduced to 4°C. The crabs were sampled every 2 h for 10 h and dissected immediately to measure the enzyme activity. The crabs at room temperature (28°C) were used as the control group. The activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX), the content of malondialdehyde (MDA) and the activity of 4 ATPases (Na+,K+-ATPase; Mg2+-ATPase; Ca2+-ATPase; Ca2+,Mg2+-ATPase) were measured biochemically. In contrast to the control group, the SOD activity increased significantly from 2 to 6 h after the cold stress, and then decreased. The CAT and GPX activities increased in 2 h, and then decreased gradually. The content of MDA increased gradually in 4 h. The activity of Na+,K+-ATPase decreased in 2 h, increased up to the top value at Hour 6, then decreased again. The activities of Mg2+-ATPase, Ca2+-ATPase and Ca2+, Mg2+-ATPase increased significantly in 6 h, insignificantly in any other hours. Under cold stress, the activity of antioxidative enzymes in S. serrata was reduced at first then stabilized, ROS-scavenging weakened, and MDA accumulated gradually in the gill after 6 h. The activity of the 4 ATPases in the crab decreased after 6 h, suggesting that the ability to regulate ion concentration has been paralyzed. Therefore, the maximum period to sustain healthy meat in the crab under cold stress is 6 hours.

HDV Ribozyme Activity in Monovalent Cations

Activity of the two ribozymes from hepatitis delta virus in monovalent salts was examined and compared to activity in Mg2+. Both ribozymes self-cleaved in high concentrations of monovalent cations, and an active site cytosine was required for cleavage activity under those conditions. Cleavage rates were 30-50-fold higher for reactions in LiCl than for reactions in NaCl or NH4Cl, and a thio effect indicated that chemistry was rate-determining for cleavage of the HDV genomic ribozyme in LiCl. Still, in LiCl, there was a more than 100-fold increase in the rate when MgCl2 was included in the reaction. However, the pH-rate profiles for the reactions in LiCl with and without MgCl2 were both bell-shaped with the pH optima in the neutral range. These findings support the idea that monovalent cations can partially substitute for divalent metal ions in the HDV ribozymes, although a divalent metal ion is more effective in supporting catalysis. The absence of a dramatic change in the general shape of pH-rate profiles in LiCl, relative to the profile for reactions including Mg2+, is in contrast to earlier data for the reactions in NaCl and limits our interpretation of the specific role played by the divalent metal ion in the catalytic mechanism.

Effect of Nano-TiO&lt;SUB&gt;2&lt;/SUB&gt; on Photochemical Reaction of Chloroplasts of Spinach

The effects of nano-TiO2 (rutile) on the photochemical reaction of chloroplasts of spinach were studied. The results showed that when spinach was treated with 0.25% nano-TiO2, the Hill reaction, such as the reduction rate of FeCy, and the rate of evolution oxygen of chloroplasts was accelerated and noncyclic photophosphorylation (nc-PSP) activity of chloroplasts was higher than cyclic photophosphorylation (c-PSP) activity, the chloroplast coupling was improved and activities of Mg2+-ATPase and chloroplast coupling factor I (CF1)-ATPase on the thylakoid membranes were obviously activated. It suggested that photosynthesis promoted by nano-TiO2 might be related to activation of photochemical reaction of chloroplasts of spinach.