STUDY ON THE FUNCTIONAL SITES OF Mg~(2+) -INDUCED Chl α FLUORESCENCE AND SURFACE CHARGE CHANGES OF THYLAKOID MEMBRANES

Thylakoid polypeptide components, Mg~(2+) -induced Chl a fluorescence at 77K and surface chargechanges were measured to investigate the functional sites of Mg~(2+) in the regulation of energy distri-bution between two photosystems in completely and incompletely developed barley chloroplasts. It wasfound that in contrast to the completely developed chloroplasts, the incompletely developed chloroplastslacked Chl b and did not contain the 23KDa and 25KDa polypeptide components of LHC-PSII. In themeantime, these membranes did nor present Mg~(2+) -induced Cbl a fluorescence and surface charge changesof thylakoids. These results provided strong evidence that the 23KDa and 25KDa polypeptides ofLHC-PSII are the specific acting sites of the cation that induced these two phenomena. It is suggested in this paper that Mg~(2+) -induced change of excitation energy distribution betweentwo photosystems is produced by the mechanism due to electrostatic neutralization of LHC-PSII bythe cation to cause a structural or con     

THE FUNCTIONAL ROLE OF 23 kD AND 24 kD POLYPEPTIDES OF THYLAKOID IN Mg~(2+)-INDUCED CHANGE OF EXCITATION ENERGY DISTRIBUTION BETWEEN TWO PHOTOSYSTEMS IN THE CHLOROPLASTS FROM Codium fragile

In contrast to the chloroplasts from higher plants, Mg~(2+)-induced PS--Ⅱ fluorescence inten-sity increase does not relate to Mg~(2+)-induced surface charge density decrease of thylakoidin the chloroplasts from Codium fragile. Tbe extraction of the green alga chloroplasts withCa~(2+) to remove the 30--31kD polypeptide (Q_B protein) on the thylakoid surface does notaffect the above Mg~(2+)-induced phenomena. If the Ca~(2+)-treated chloroplasts are further di-gested by trypsin to remove the 23kD and 24kD polypeptides on the membrane surface,the Mg~(2+)-induced fluorescence effect will completely disappear whereas the property ofMg~(2+)-induced surface charge density changes remains unchanged. These results not onlyshow that the 23kDa and 24kDa polypeptides on the thylakoid surface are the specific act-ing sites of the cation that induce Chla fluorescence change, but also demonstrate that thecation-induced change of excitation energy distribution between two photosystems is not con-trolled by the electros     

Mg~(2+)-MEDIATED CHANGES IN FLUIDITY OF PHOSPHOLIPID DECREASE THE SLOW MOTION OF THE INCORPORATED H~+-ATPase IN LIPOSOMES

The effect of Mg~(2+) on the slow motion of H~+-ATPase in proteoliposome was studied. The ST-ESR spectra of H~+-ATPase labeled with maleimide and incorporated in liposomes at various Ma~(2+)concentrations with incubation method were measured. The relationship between the diagnostic param-eters L"/L, C'/C derived from ST-ESR spectra and Mg~(2+) concentrations or temperatures was com-pared with that of the order parameter S derived from 5NS-ESR spectra under the same conditions. Obtain-ed results clearly showed that the increase of Mg~(2+) concentration or the decrease of temperature maycause the increase of the rotational correlation time of H~+-ATPase in proteoliposome. And the rota-tional diffusion rate of H~+-ATPase in membrane lipid is related to the activation energy of the sur-rounding lipid. The change of Mg~(2+) concentration in proteoliposome leads to a change of activarionenergy and influence in turn the slow motion of H~+-ATPase in 1ipid.     

PHOTO-INDUCED GRAFT POLYMERIZATION OF ACRYLAMIDE ON POLYPROPYLENE MEMBRANE SURFACE IN THE PRESENCE OF DIBENZYL TRITHIOCARBONATE

Ultraviolet （UV）-induced graft polymerization of acrylamide （AAm） on polypropylene substrates was successfully conducted using dibenzyl trithiocarbonate （DBTTC） as photoinitiator. It was confirmed by chemical analysis and surface morphology observation with attenuated total reflectance Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. A possible mechanism for this graft process was presented, which suggested that, under UV irradiation, the C： S bond in DBTTC could split and abstract a hydrogen from the polypropylene surface and a surface free radical was then formed, and initiated the graft polymerization of AAm.     

STUDY ON THE INTERACTION OF Se AND ERYTHROCYTE MEMBRANE——PROTECTIVE EFFECT OF Se ON THE ERYTHROCYTE MEMBRANES

During the ageing of erythrocyte membrane, the spectrin content, Na, K-ATPase activity as well as the lipid fluidity are obviously decreased. However, supplementation of a trace amount of Na_2SeO_3 in the medium could prevent the dissociation of spectrin from membrane and delay the changes of Na, K-ATPase activity and lipid fluidity. The effectiveness is proportional to Se concentration within the range of 0.1—1.0 ppm.Similar effect of supplementation of Se on the intact erythrocytes during ageing has been also observed.The protective action of Se on biomembranes is generally interpreted in terms of the activity of Se-containing glutathione peroxidase (GSHPx). However, GSHPx mainly distributes in the cytoplasma of erythrocytes, therefore it seems that the protective action of supplemented Se on the isolated erythrocyte membrane might not be related to the activity of GSHPx.     

THE EFFECTS OF MOLECULAR STRUCTURE ON PARAMETERS a, b AND c IN RETENTION EQUATION AND PREDICTION OF CAPACITY FACTORS IN RP-HPLC

In this paper, the effects of molecular structure on the parameters a, b and c in retention equation are investigated theoretically and experimentally. Parameter b in RP-HPLC approaches a small constant, because there is very weak displacement adsorption. Parameter c in RP-HPLC is mainly determined by the difference between solute-strong solvent and solute-weak solvent interaction and can be quantitatively correlated with the structural parameters of solute such as van der Waals volume (Vw), dipole moment (μA) and hydrogen bond energy (XAH). Parameter a has similar rules to parameter c. The prediction of k' value for non-polar, homologous compounds is studied. The linear relationship between k' and coverage of amount of the bonded chain in RP-HPLC is confirmed.     

STUDIES ON THE ESR CHARACTERISTICS OF FOUR PIPERIDINE NITROXYL RADICALS——CHARACTERISTICS IN THE SOLID STATE,CONCENTRATION EFFECTS AND SOLVENT EFFECTS IN SOLUTIONS

The ESR characteristics are studied for four piperidine nitroxyl radicals in the solidstate and in solutions. They all exhibited singlet ESR spectra in the solid state, but tripletspectra in solutions at a concentration lower than 1×10~(-2)M. The effects of the free radi-eal coneentration and the polarity trod the viscosity of solvents were observed and comparedon five ESR spectral parameters. Linear correlations could be found between the hyperfinesplitting constant A_N and the solvent polarity parameter, namely, Kosower Z value, Ex-perimental data showed also linear relations of the rotational correlation time τ of free rad-icals with the solvent viscosity, η. We have further found that the relative height of thehigh-field peak varied inversely with η. These ESR characteristics of nitroxyl radicals arediscussed.     

STUDIES ON THE ACTIVITY COEFFICIENTS OF NONELECTROLYTES IN AQUEOUS SALT SOLUTIONS——Ⅱ. THE EFFECTS OF SALTS OF FATTY ACIDS AND QUATERNARY AMMONIUM SALTS ON THE SOLUBILITIES OF NAPHTHALENE IN WATER

On the assumption that the salt effect (salting-out or salting-in) representsthe balance of the electrostatic effect between the ion and the water dipole andthe dispersion effect between ion and nonelectrolyte molecule, the solubilitiesof n-valeric acid in five cobaltammimes were studied and reported in article Ⅰof this series. In the present investigation the activity coefficients of naph-thalene in two series of salts are determined spectrophotometrically. The firstseries consists of seven sodium salts of fatty acids (sodium formate to sodiumn-heptylate), differing from one another only by the number of CH_2 groups inthe anions. The second series consists of ammonium bromide and three tetra-     

A STUDY ON THE INTERACTION BETWEEN CH_3OH AND H_2CO MOLECULES IN TERMS OF THE PROPERTIES OF CHARGE DENSITY DISTRIBUTIONS

Two possible complexes formed by the interaction of CH_3OH and H_2CO,one hydrogen-bonded(Ⅰ)and one donor-acceptor complex(Ⅱ),have been reported in the previous paper.Based on theab initio 6-31G basis set calculations,the properties of the charge density for the complexeshave beenanalyzed using the theory of atoms in molecules.The nature of the complex formation has beendiscussed in terms of the properties of the charge density distributions.     

THE EFFECTS OF PERFUSION OF LATERAL VENTRICLE WITH CaCl_2 ON THE FEBRILE RESPONSE AND cAMP CONTENT IN PLASMA AND CEREBROSPINAL FLUID DURING LP-INDUCED FEVER

Artificial cerebrospinal fluid (c.s.f.) containing 40 mmol/L excess calcium was perfus-ed through the lateral ventricles of New Zealand white rabbits in order to reduce the Na~+/Ca~(++) ratio in the brain and the effects on both the febrile response and adenosine cyclic mo-nophosphate (cAMP) concentration in plasma and c.s.f, during leucocytic pyrogen (LP)-induced fever were observed. The results showed that cAMP concentration in c.s.f, increas-ed significantly during LP-induced fever while the cAMP level in Plasma remained unchang-ed, and the perfusion of artificial c.s,f, containing 40 mmol/L excess calcium can signif-icantly inhibit not only the febrile response but also the increase in c.s.f, cAMP level,while there appears no effect on plasma cAMP concentration, thus demonstrating that theincrease of Na~+/Ca~(++) ratio causing the increase of cAMP content in the brain may be anessential link in the pathogenesis of LP-induced fever.     

EFFECTS OF RATE OF ADDITION AND TENIPERATURE ON THE ENANTIOSELECTIVITY IN BORANE REDUCTION OF KETONES CATALYZED BY CHIRAL OXAZABOROLIDINE

ＥＦＦＥＣＴＳＯＦＲＡＴＥＯＦＡＤＤＩＴＩＯＮＡＮＤＴＥＮＩＰＥＲＡＴＵＲＥＯＮＴＨＥＥＮＡＮＴＩＯＳＥＬＥＣＴＩＶＩＴＹＩＮＢＯＲＡＮＥＲＥＤＵＣＴＩＯＮＯＦＫＥＴＯＮＥＳＣＡＴＡＬＹＺＥＤＢＹＣＨＩＲＡＬＯＸＡＺＡＢＯＲＯＬＩＤＩＮＥＹａｏＺｈｏ...     

MICROENVIRONMENTAL EFFECTS OF THE HELICAL CONFORMATIONS OF AMYLOSE AND ITS DERIVATIVES——CATALYTIC EFFECTS OF SODIUM CARBOXYMETHYLAMYLOSE ON THE HYDROLYSIS OF VARIOUS ESTERS OF N-ALKYL-3-HYDROXYPYRIDINIUM IODIDE

Hydrolysis of various carboxylic esters of N-alkyl-3-hydroxypyridinium iodide(2—5) has been studied, both in the absence and in the presence of sodium carboxymethylamylose(NaCMA 1). In the absence of Na-CMA, the hydrolysis of all four substrates follows 2nd-order kinetics when HPO_4~- and CH_3CO_2~- ions are used as the attacking nucleophites. In the presence of 1, however, the course of the reaction depends on the structure of the substrates. For 2 and 3, the observed rate constants k_(obs) are independent of the eoncentration of 1 added, but for those with long hydrocarbon chains, i. e. 4 and 5, the hydrolysis follows MichaelisMenten kinetics. All other experimental results also indicate the formation of supramolecular(incluston) complexes between the Na-CMA host molecules in helical conformations and theesters 4 and 5. In comparison with the bimolecular processes in the bulk phase, the catalytic efficiencies(k_c/K_d) of these supramolecular systems are 3.7×10~4 and 1.7×10~4 times that of the aceta     

TIME-RESOLVED FLUORESCENCE STUDY OF TRIPLE EXCIPLEX FORMED IN THE SYSTEM OF POLY(2-VINYL) NAPHTHALENE AND TEREPHTHALIC DIMETHYLESTER

An intramolecular excimer of poly(2- vinyl) naphthalene was formed by non-adjacentchromophores interaction, then a triple exciplex was formed by interaction with the acceptormolecule further in dilute solution. The lifetime of the intramolecular excimer of poly(2-vinyl) naphthalene, τ_2 = 18.83 ns and the rate constant for the triple exciplex formation,k_7 = 4. 18× 10~9 (mol/L)~(-1)s~(-1), under diffusion-control were measured. An excimer or anexciplex could be an intermediate of the triple exciplex formation. A theoretical model ofthe triple exciplex formation is proposed.     

STUDY ON THE TREATMENT AND REUSE OF WASTEWATER FROM THE PRODUCTION OF 2—NAPHTHANOL

Systematic studies on the treatment and reuse of the acid industrial watewater containing sodium 2-Naphthylsulfonate(β-salt)from 2-Naphthanol production process by ND-910 resin (made by self) is reported in this paper.Under the operation conditions of initial β-salt concentration of 10000-25000mg/L and initial CODCr of 20000-40000mg/L,the removal rates of Sodium 2-Naphthylsulfonate and CODCr are over 95% and over 89%,respectively.The effluent can be discharged directly after biological degradation.The working sorption capacity of ND-910 Resin for β-salt is over 230g/kg.An alkali-water wash procedure isutilized to regenerate resin and the reclaiming rate of β-salt is over 98%.     

EFFECTS OF SOLVENT TREATMENT ON SURFACE MORPHOLOGY AND COMPOSITION OF POLY(METHYL METHACRYLATE)-g-POLY(ETHYLENE OXIDE)

Surface morphology and composition of solution-cast films of poly(methyl methacrylate)-g-poly(ethylene oxide)(PMMA-g-PEO) were investigated by using XPS, DSC, SEM and contact angle measurement. The microphase separatedstructure of the copolymers was studied by TEM. Generally, for the same graft copolymer, the surface content of PEO orhydrophilicity can be as follows: Surface treated with petroleum ether or cyclohexane>surface untreated with solvent>surface treated with water or ethyl alcohol. Graft copolymer having longer PEO side chains and higher PEO content shows aseparated PEO phase with even a certain degree of crystallinity on the surface. PEO crystallinity was destroyed by water orethyl alcohol treatment, however, surface treatment with petroleum ether or cyclohexane favors the growth of PEO crystal.TEM shows that graft copolymers with longer PEO side chains (M_n of PEO, 3200) may readily undergo microphase separation and the shape and size of domains depend on the copolymer's composition.     

APPLICATION OF XPS TO STUDYING DISPERSION AND SURFACE STATE FOR MoO_3 SUPPORTED ON THE SURFACE OF TiO_2, γ-Al_2O_3 AND SiO_2

In MoO_3/TiO_2, MoO_3/γ-Al 2O_3 and MoO_3/SiO_2 systems, the relationships between I_(Mo3d)/I_(Ti2p), I_(Mo3d)/I_(Al2p), I_(Mo3d)/I_(Si2p) and added amount of MoO_3(g/g carrier) were studied by XPS. Experiments showed that all the curves obtained had a turning point each, corresponding to the monolayer dispersion threshold by XRD in our previous paper. This means that both methods are successful for studying the maximum dispersion amount and surface state of supported metal oxides (or salts) catalysts. Although the two methods are not from the same principle, they are verifiable and complementary to cach other in studying dispersion problems.     

STUDIES ON THE MECHANISM OF INDIRUBIN ACTION IN THE TREATMENT OF CHRONIC GRANULOCYTIC LEUKEMIA——V.BINDING BETWEEN INDIRUBIN AND DNA AND IDENTIFICATION OF THE TYPE OF BINDING

The binding between indirubin and calf thymus DNA in vitro has been verified by meansof the isotope labelling method, spectrophotometric method and thermal denaturation meas-urements. The λ_max 207 nm of indirubin shifted toward longer wave length with decrease ofabsorbance after the incubation of indirubin with DNA. The escalation of Tm value of DNAinduced by indirubin was about 2.4°C and it was reproducible. The binding force between themwas rather weak, as indirubin molecules were easily released during the precipitation withalcohol or the gel filtration. The binding was not affected by sodium chloride even at high con-centration but greatly decreased (to 20-30% of the control) in the presence of 8 M urea.These results showed that the binding between indirubin and DNA might be of hydrogen bondrather than ionic. The amount of bound ~3H-indirubin was directly proportional to the con-centration of indirubin. However, it increased abruptly when the concentration of indirubinreached 1.5×10~(-4) M. This     

STUDIES ON THE STRUCTURE OF FORKED CONJUGATIVE SYSTEMS——THE CRYSTAL STRUCTURE AND CONFORMATION OF 2-BENZOYLTHIOPHENE

The crystal structure and the conformational properties of the title compound have been investigated by means of X-ray single diffraction and the PCILO methods. C_(11)H_8OS belongs to the orthorhombic system, the space group is P2_12_12_1, a=11.945(4), b 10.236(7), c=7.649(4), Z=4, D_c-1.37g/cm~3. The molecule is not planar structure because of steric hindrance. The thiophene ring and the phenyl ring make dihedral angles of 21°(θ_1) and 32°(θ_2) with the carbonyl frame plane, respectively. The lowestenergy conformation obtained by PCILO calculation is in agreement with the crystallinestatc conformation. In this paper, the molecular structure, the influence of steric hindrance and the groups' abilities to conjugate upon the conformation and the variations of the potential energy of the isolated molecule in the whole conformational space are discussed.     

THE COORDINATION ADSORPTION OF AMINES ON CARBOXYL RESIN IN Cu~(2+) FORM FROM NON-AQUEOUS MEDIUM AND DESORPTION WITH ANHYDROUS ELUANT

The adsorption of aniline, N-methylaniline and N,N-dimethylaniline onto carboxyl resin in Cu~(2+) form from water,ethanol and n-hexane have been studied. The results show that the adsorption affinities from n-hexane are higher than thatfrom water, and nearly zero from ethanol. The separation factors for the adsorption of these three amines from mixed solutionwere also examined. The results of continuous column operations show that the breakthrough capacity of aniline from n-hexane reaches 90 mg/g dry resin in Cu~(2+) form, and the amines adsorbed can be stripped with anhydrous ethanol effectively.Adsorption onto carboxyl resin in Cu~(2+) form from non-aqueous medium and desorption with anhydrous eluant can overcomethe run-off of Cu~(2+) from the resin, and would show potential advantages in the separation of some water-insoluble naturalproducts.     

MICROENVIRONMENTAL EFFECTS OF THE HELICAL CONFORMATIONS OF AMYLOSE AND ITS DERIVATIVES——THE FORMATION OF INCLUSION COMPLEXES WITH A SUBSTRATE BY AMYLOSE IN THE DMSO-H_2O MIXED-SOLVENT SYSTEM

The conformational behavior of amylose and the formation of helical inclusion complexesof amylose with a substrate, N-ethyl-4-hexadecyloxycarbonyl pyridinium iodide (1) -- asolvent-polarity probe, have been investigated in the DMSO--H_2O mixed-solvent system bymeans of surface tension, viscosity, UV, electrical conductance and ORD measurements. Thedecrease of the volume-fraction of DMSO, Φ_(DMSO) of the mixed-solvent system inducesconformational changes of the amylose from tight helices to loose and extended helicesinterrupted by short disordered regions. Such a transition is accompanied by abrupt changesof the viscosity and ORD curves. The mechanism of interaction between amylose and the substrate 1 also depends on thesolvent composition. When Φ_(DMSO) is larger than 0.70, the interaction of amylose with 1is apparently similar to those cases in which superhelices are formed between a macromo-lecule and some azo dyes; the latter are known to be bound exteriorly around the macro-molecular helices by oriented association. However, when Φ_(DMSO) begins to drop below0.70, the substrate molecules start to be bound in the helical cavities of the host and thussupramolecular inclusion complexes are formed. At Φ_(DMSO)<0.70, ORD shows a new nega-tive Cotton peak at a wavelength which coincides with the λ_(max) of 1 (276 nm). This implicatesinduced asymmetry for the achiral substrate 1 in a chiral microenvironment. Intrinsicdissociation constants (K_(d~*)) for the inclusion complexes can be obtained from the surface ten-sion- substrate concentration (σ-[1]) curves and the largest number of binding sites isfound to be below 30. The K_(d~*) values decrease with decreasing Φ_(DMSO), apparently inagreement with the results from conductance measurements. Presumably, the driving forcefor the transfer of the substrate molecules from the solvent-mixture bulk phase to the non-polar cavities of the host molecules comes from hydrophobic-lipophilic interactions.