Effects of truncated mutants of the ε subunit of chloroplast ATP synthase on the fast phase of millisecond delayed light emission of chloroplast and its ATP synthesis ability

The ε subunit of the chloroplast ATP synthase and the truncated ε mutants which lack some amino acid residues from the N-terminus or C-terminus were overexpressed in E. coil When the ε subunit or the truncated ε proteins was added to the spinach chloroplast suspension, both the intensity of the fast phase of millisecond delayed light emission (ms-DLE) and the cyclic and noncyclic photophosphorylation activity of chloroplast were enhanced. With an increase in the number of residues deleted from the N-terminus, the enhancement effect of the N-terminal truncated proteins decreased gradually. For the C-terminal truncated proteins, the enhancement effect increased gradually with an increase in the number of residues deleted from the C-terminus. Besides, the ATP synthesis activity of ε-deficient membrane reconstituted with the ε subunit or the truncated ε proteins was compared. The ATP synthesis activity of reconstituted membrane with the N-terminal truncated proteins decreased gradually as the number of residues deleted from the N-terminus increased. For the C-terminal truncated proteins, the ATP synthesis activity of reconstituted membrane increased gradually with an increase in the number of residues deleted from the C-terminus, but was still lower than that of the wild type ε protein. These results suggested that: (a) the N-terminal domain of the ε subunit of the chloroplast ATP synthase could affect the ATP synthesis activity of ATP synthase by regulating the efficiency of blocking proton leakage of ε subunit; and (b) the C-terminal domain of the ε subunit of the chloroplast ATP synthase had a subtle function in modulating the ATP synthesis ability of ATP synthase.     

Direct observation of the clockwise light-driven rotation of F<Subscript>0</Subscript>F<Subscript>1</Subscript>-ATP synthase complex

The purified thermophilic bacterium PS3 F₁ β _10×His-tag is inserted into the F_oF₁-ATP synthases of chro-matophores isolated from photosynthetic bacteria Rhodo-spirillum rubrum. The studies of biochemical properties of the hybrid chromatophores show that they have both protons-driving capability and photophosphorylation. The fluorescent actin filaments, as a marker of its orientation by video-microscopic experiment, are connected via Maleimido-C₃-NTA to the reconstituted β_10×His-tag of F_oF₁-ATP synthases. The clockwise rotation of F_oF₁-ATP synthases driven by light is observed directly when viewed from the F_o side to F₁. This system should be valuable for further studying the coupling property of F_oF₁-ATP synthase.     

The composition and distribution of metal clusters in the MoFe protein from a nifZ deletion strain （DJ 194） of Azotobacter vinelandii

Through the anaerobic chromatography on the columns of DEAE 52, Q-Sepharose and Sephacryl S-200, a nitrogenase MoFe protein (△nifZ Av1) was obtained from a nifZ deleted mutant of Azotobacter vinelandii (stain DJ194).The results of Western blotting after anoxic native electrophoresis and SDS-PAGE showed that △nifZ Av1 was similar to wild type MoFe protein (OP Av1) at the electrophoretic mobility, molecular weight and subunit composition. Furthermore, △nifZ Avl was also similar to OP Av1 at the molybdenum content, EPR signal (g≈4.3, 3.65 and 2.01), and the molar extinction coefficient (△ε) of circular dichroism (CD)at 660 nm region. All of these indicated that, besides having the same α2β2 composition as OP Av1, the △nifZ Av1 also contained equal amount of reductive FeMoco in the spin state of S=3/2 to OP Av1. However, the iron content and substrate (C2H2, H^ and N2)-reduction activity of △nifZ Av1 were 74% and 46%-50% of those of OP Av1, respectively. Furthermore, the △ε at around 450 nm, which reflects P-cluster in Av1, was obviously lower than that of OP Av1. It suggested that the difference between △nifZ Avl and OP Av1 resulted from P-cluster rather than FeMoco, and from the half number of P-cluster in △nifZ Av1, but the composition or redoxstate of P-cluster in △nifZ Av1 were not changed. Thus it could propose that △nifZ Av1 is composed of two different αβsubunit pairs. One is a FeMoco-and P-cluster-containing pair, and the other is a P-cluster-deficient but FeMoco-containing pair. Since the deletion of nifZ gene leads to the deficiency of only one of two P-clusters in a α2β2 tetramer, the assembly of P-cluster may not simply depend on one gene product, and so a possible mechanism of NifZ is supposed here.     

ATPG is required for the accumulation and function of chloroplast ATP synthase in Arabidopsis

The subunit Ⅱ of chloroplast ATP synthase is one of the two peripheral stalks, which associates the catalytic CF1 with mem-brane-spanning CFo . Although the structural and functional roles of chloroplast ATP synthase have been extensively examined, the physiological significance of subunit Ⅱ in vivo is still unclear. In this work, we identified one Arabidopsis T-DNA insertion mutant of atpG gene encoding the subunit Ⅱ of chloroplast ATP synthase. The atpg null mutant displayed an albino lethal pheno-type, as it could not grow photoautotrophically. Transmission electron microscopy analysis showed that chloroplasts of atpg lacked the organized thylakoid membranes. Loss of subunit Ⅱ affected the accumulation of CF1-CFo complex, however, it did not seem to have an effect on the CF1 assembly. The light induced ATP formation of atpg was significantly reduced compared with the wild type. Based on these results, we suggested that ATPG was essential for the accumulation and function of chloroplast ATP synthase.     

Existence of single-peaked solution of a semilinear elliptic problem

We discussed the Dirichlet problem of semilinear elliptic equationin (Pβ,α)D;-β△u=uε+εu,u>0,in Ω u=0, on(e),Ω where Ω(∪)RN(N≥4) is smooth and bounded domain,P=N+2/N-2,β,ε>0. We have proved that there exist positive ε0 and ε1 , such that when 0≤ε≤ε0,β>√ε1,(P0,1)has a single-peaked solution uβ, furthermore, |▽μβ|-0in the sense of measure as ε→0 and β→0.     

Two-dimensional crystallization and preliminary electron crystallographic result of partially purified F<Subscript>0</Subscript> from porcine mitochondria

After removal of cytoplasmic sector F₁ from submitochondrial particles of F₀F₁-ATP synthase complex with guanidine hydrochloride, the transmembrane sector F₀ was specifically extracted from the stripped membranes in the presence of detergent CHAPS and partially purified. Two-dimensional crystals were produced by the reconstitution of the partially purified F₀ into asolectin and microdialysis. The obtained crystals are able to diffract to 2 nm. The projection map of the negatively stained crystal shows that the crystal has p42₁2 symmetry, lattice constant, a=b=14.4 nm. A unit cell contains four F₀ molecules.     

A Large Deviation Principle for the Risk Process with Varying Premium

Let u ∈ R ,for any ω 〉 0, the processes X^ε = {X^ε（t）; 0 ≤ t≤ 1} are governed by the following random evolution equations dX^ε（t）= b（X^ε（t）,v（t））dt-εdSt/ε, where S={St; 0≤t≤1} is a compound Poisson process, the process v={v（t）; 0≤t≤1} is independent of S and takes values in R^m. We derive the large deviation principle for{（X^ε,v（.））; ε〉0} when ε↓0 by approximation method and contraction principle, which will be meaningful for us to find out the path property for the risk process of this type.     

An exact expression for fractional absorption in Mossbauer spectroscopy

The fractional resonance absorption ε(0) in transmission Mossbauer spectroscopy is defined as a relative number of the absorbed γ-ray, and regarded as a measure of Mossbauer effect. The absorption linewidth Λ _a , as it is usually suggested, is nearly equal to the emission linewidth, Λ _s , and such an approximation leads to a extremely simplified expression ε(0), depending on neither Λ _s nor Λ _a . We consider the general case Λ _s ≠Λ _a , and obtain an exact expression for ε(0) which is given in the present paper. This expression ε(0), as a function oft _a, Λ _s , Λ _a , is figured and discussed. Biography: Chen Yi-long (1934-), male, Professor, research interest: Mossbauer effect and its applications.     

Magnetic properties and giant magnetoresistance effect of nanometer Fe−In2O3 granular films

Nanometer ferromagnetic metal-semiconductor matrix Fe−In₂O₃ granular films are fabricated by the radio frequency sputtering. Magnetic properties and the giant magnetoresistance (GMR) effect of Fe_x(In₂O₃)_1−x granular film samples are studied. The result shows that the magnetoresistance (MR) ratio Δρ/ρ ₀ value of the granular film samples with Fe volume fraction x=35% is 4.5% at room temperature. The temperature dependence (T=1.5–300 K) of the MR ratio Δρ/ρ ₀ value of Fe_0.35(In₂O₃)_0.65 granular films shows that Δρ/ρ ₀ value below 10 K increases rapidly with the decrease of the temperature, and when T=2 K, Δρ/ρ ₀ value is 85%. Through the study of the dependence of low field susceptibility on temperature and the hysteresis loops at different temperatures, it has been found that, when the temperature decreases to a critical point T _p=10 K, the change of the structure in Fe_0.35)In₂O₃)_0.65 granular films results in the transformation of state from ferromagnetic to spin-glass-like. The remarkable increase of the MR ratio Δρ/ρ ₀ value of Fe_0.35(In₂O₃)_0.65 granular films below 10 K seems to arise from the peculiar conducting mechanism of the granular film samples in the spin-glass-like state.     

Functional Imaging of Breast Tissue and Clinical Application

0Introduction Near infrared(NIR)techniquesarebasedonsensitive,quantitativemeasurementsoffunctionalcontrastbe tweenhealthyanddiseasedtissue.Recently,researchersshowgreatinterestinmeasuringfunctionalpropertiesofbreasttis suesuchashemoglobinconcentrationoroxygensaturationbyNIRspectroscopyandNIRimaging[1,2].NIRlightcanpene trateseveralcentimetersintotissuebeforeitisattenuatedbe lowdetection.ThemainintrinsicmechanismsofNIRlightat tenuationintissuearethescatteringduetoindexofrefractionvariatio…     

On the Pólya conjecture and the weak Weyl-Berry conjecture

The Pólya conjecture and its connection with the weak Weyl-Berry conjecture are studied Specifically let Ω⊆R ⁿ (n≥1) be a non-empty bounded open set with boundary ∂Ω. LetN ₀(λ, −Δ,Ω) be the Dirichlet counting function and φ(λ) the associated Weyl term. If the interior Minkowski dimension of ∂Ω is δ∈[n−1,n], then under certain realisable conditions we prove that for λ sufficiently large the Pólya conjecture φ(λ) −N ₀(λ,−Δ,Ω)≥0 is true. Under related conditions we also prove thatϕ(λ)−N ₀(λ,−Δ, Ω)≈λ^5/2, as λ→+∞. That is, the Weak Weyl-Berry conjecture is true. Similar results are obtained for the Neumann counting function. Partially supported by the National Natural Science Foundation of China and the Royal Society of London Chen Hua: born in March 8, 1956, Professor     

Chaos in the sense of Li-Yorke and the order of the inverse limit space

Let I= [0,1] and ω0 be the first limit ordinal number. Assume that f: I→I is continuous , piece-wise monotone and the set of periods of f is { 2': i∈ {0} ∪ N}. It is known that the order of (I, f) is ω0 or ω0 + 1. It is shown that the order of the inverse limit space (I, f) is ω0 (resp. ω0 + 1) if and only if f is not (resp. is) chaotic in the sense of Li-Yorke.     

Crystal structures of catalytic and regulatory subunits of rat protein kinase CK2

Protein kinase CK2 consists of two catalytic subunits (CK2α) and two regulatory subunits (CK2β). Here, we report the crystal structures of rat CK2α mutant (rCK2α-△C, 1—335) and CK2β (rCK2β). The overall topology of rCK2α-△C and rCK2β are very similar to the human enzyme, although large structural differences could be observed in the N-terminal domain of rCK2α-△C. Our reported structure of rCK2α-△C is in the close conformation state while the counterpart hCK2α is in the open conformation state, indi- cating ...     

Rational design of glycerol dehydratase： Swapping the genes encoding the subunits of glycerol dehydratase to improve enzymatic properties

1,3-propanediol (1,3-PD) is an important material for chemical industry,and there has been always much interest in the production of 1,3-PD using all possible routes. The genes encoding glyc-erol dehydratase (GDHt) from Citrobacter freundii,Klebsiella pneumoniae and metagenome were cloned and expressed in E. coli. All glycerol dehy-dratases but the one from metagenome could be detected to show enzyme activities. In order to im-prove the enzymatic properties of GDHts,the genes encoding α and β-γ subunits were cloned,and the enzyme characteristics were evolved by rational de-sign based on their 3D structures which were con-structed by homology modeling. Six heteroenzymes were obtained by swapping the α subunit genes of these three different-source-derived GDHts. The pH,thermal stability and Vmax of some heteroenzymes were dramatically improved by 2―5 times compared with the wild one (GDHtKP). The GDHt cloned from metagenome,originally proved to be with no enzyme activity,was converted into active enzyme by swap-ping its subunits with other different GDHts. In addi-tion,the effect of subtle 3D structural changes on the properties of the enzyme was also observed.     

Determination of free energy of protein folding on liquid-solid interface

Based on the fact that the stoichiometric displacement model for retention of solute and the total adsorption free energy of solute on a solid surface can be divided into two components, net adsorption and net desorbed energies, a new principle and an equation for calculating the free energy of protein folding, △△GF, on the solid surface are proposed. With high-performance hydrophobic interaction chromatography (HPHIC), an experimental method for determining the △△GF is established. Lysozyme and α-amylase have been selected as examples to test the new method, and their △△GF on the HPHIC stationary phase surface are found to be much higher than that reported from a solution. In addition, the △△GF of the two proteins are found to increase with the concentration of denaturing agent employed. The average standard deviations, ±4.7% for lysozyme and ±3.0% for α-amylase, indicate that the new method has a satisfactory reproducibility and reliability.     

Removing the impact of wind direction on remote sensing of sea surface salinity

Sea surface salinity (SSS) plays an important role in the sub-polar area, where intrusions with low salinity influence the deep thermohaline circulation and the meridional heal transport. SSS fields and their seasonal and inter-annual variability are thus…     

Simulation of maximum light use efficiency for some typical vegetation types in China

MAXIMUM LIGHT USE EFFICIENCY(ΕMAX)IS THE USE RATE OF PHOTOSYNTHETICALLY ACTIVE RADIATION BY VEGETATION IN AN IDEAL CONDITION WITHOUT ANY CONSTRAINTS.IT IS A PHYSIOLOGICAL ATTRIBUTE OF PLANT ITSELF.THE VALUE OFΕMAX IS DIFFERENT FOR DIFFERENT VEGETATION TYPES[1―5].IT IS A KEY PARAMETER FOR THE ESTIMATION OF NET PRIMARY PRODUCTIVITY(NPP)DRIVEN WITH REMOTE SENSING DATA.THERE…     

Determination of crystal structure of omphacite

The chemical formula of omphacite was expressed with (MⅡ MⅠ ) (Si, AI)2O6. Cations that occupied the MⅡ site were large cations such as Ca or Na, and (Na/(Na+Ca)) ratio ranged from 0.2 to 0.8; the 6-coordinated MⅠ site accommodated cations such as Mg, Fe2+, Al, Fe3+ ,and(AI/(AI+Fe3+)) ratio was more than 0.5. Omphacite space groups reported were C2/ c, P2, P2/n, P2/c, cell parameters are α0 = 0.9600-0.9630 nm,b0 = 0.8750-0.8830 nm,c0 = 0.5230-0.5290 nm,β = 106°40′-107°10'. The sample was picked up from the eclogites in Zhucheng County, Shangdong Province. The intensity data were collected with the RIGAKU RASA Ⅱ -S four-circle single crystal diffractometer.The correct structure model was obtained by using the Patterson method and Fourier synthesis, SHELX-76 program, structure refinement with 905 independent diffraction points (| F0 |> 3σ |F0 |). After the structure parameter refinement, the R-factor reduced to 0.0515. The crystal structure analysis indicates that omphacite has a new space group-Pn space group.     

Latitudinal shift and tilt of the ring current during magnetic storms

The equatorial ring current (ERC) theory suggested that the distribution of global disturbed horizontal geomagnetic field only depends on the cosine of station’s latitude. However, we always observe a larger ΔH at higher latitude stations than lower ones, implying that the ERC could tilt or/and shift with respect to the equatorial plane during intense storms. In this paper, we analyze 11 intense magnetic storms from 2000 to 2004, and introduce two configurational factors to characterize the topology of storm time ring current. The results show that ERC has occasionally deviated off equatorial plane with both tilt angle δ_t≈13°―25° and latitude shift δ_s≈0°―21.8°. The ground disturbed field distribution should be improved as ΔH_k = ΔH_maxcos(φ_k-δ ), which agree well with the geomagnetic observations.