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.     

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...     

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.     

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.     

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.     

EFFECTS OF La_2O_3 LOADING MANNER ON THE CHEMISORPTION AND HYDROGENATION OF CO ON La_2O_3-PROMOTED Pd/siO_2

The effects of La_2O_3 as a promoter of Pd/SiO_2 catalyst and its loading manner on thechemisorption and hydrogenation of CO have been investigated using in situ FTIR,TPSR,CO adsorp-tion,activity evaluation of methanation and TEM.The results show that the addition of La_2O_3 to thePd/SiO_2 can promote the dissociation and hydrogenation of CO,but causes a noticeable suppression inchemisorption of CO.This is probably due to partially reduced La_2O_3 moieties which decorate the sur-face of Pd particles.In addition,the effects of La_2O_3 promotion on the adsorptive and reactive propertiesof Pd/SiO_2 depend strongly on the loading manner of La_2O_3.It means that the method of preparationhas a significant effect on the degree of interaction between La_2O_3 and the surface of Pd particles.     

CONFORMATIONAL ANALYSIS ON ANTICHOLINERGIC DRUG (Ⅰ) MOLECULAR MECHANICS MMPM CALCULATION OF ATROPINE AND OTHER ALKALOIDS IN THE BELLADONNA PLANT

Alkaloids of balladonna plant were studied by molecular mechanics MMPM calculation. The results showed that the ideal conformation was quite different from the structure found in the crystals of the alkaloids in belladonna plant. The intramolecular hydrogen bond was present between the hydroxy group and carbonyl oxygen atom in the ideal conformation for these alkaloids. The origin of asymmetrical molecules in nature obeys the lowest energy principle. This may be a reason why only S-(-) not R-(+)-isomer, only hyoscyamine not pseudotropine were found to be present in natural belladonna plant, The model of four recognition sites between anticholinergic drug-receptor interaction in mydriasis was suggested, in which the hydroxy group with 8～9 A distanced from nitrogen atom is possibly necessary for maximum mydriasis activity.     

A PRELIMINARY STUDY ON THE IMMUNODIAGNOSIS OF PARAGONIMIASIS——THE PHYSICO-CHEMICAL AND IMMUNOLOGICAL CHARACTERISTICS OF THE CRUDE AND PARTIALLY PURIFIED ANTIGENS OF THE PARAGONIMUS WESTERMANI (LIAONING)

We have now succeeded in preparing a partially purified antigen (Fr. 1). The positive rates of the indirect ELISA were 100% both for sera of proved human cases and dogs infected with Paragonimus westermani when Fr. 1 was used, whereas the positive rates of the test were 71.4% and 75% on sera from patients and infected dogs respectively when crude antigen was used. Moreover, it is also better than the crude antigen in specificity, so a more reliable test in immunodiagnosis of paragonimiasis is available in our laboratory.     

PREPARATION AND THE CULTURE OF LO2 CELLS ON PVA—BASED MICROCARRIERS

Using polyvinyl alcohol(PVA) as raw material and vacuum pump oil as oil phase medium,PVA-based microcarriers were prepared by suspension method,The diameters of the beads were 100-180um,LO2 cells were cultured on PVA-based microcarriers and cytodexⅢ microcarriers.Morphology,attachment and growth rate of LO2 cells were studied.     

CATALYTIC ASYMMETRIC EPOXIDATION OF a－FURFURYLAMINE IN THE PRESENCE OF MOLECULAR SIEVE AND CaH_2

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EFFECT OF TRANSMEMBRANE Ca~(2+) GRADIENT ON CONFORMATION AND ENZYME ACTIVITY OF RECONSTITUTED ADENYLATE CYCLASE

Adenylate cyclase from bovine brain cortex was reconstituted into asolectin liposomes with (500-fold) or without transmembrane Ca~(2+) gradient. The enzyme activity of four types of proteoliposomes (the active center of enzyme exposing outside) was compared. The highest adenylate cyclase activity was observed in the vesicles with outside lower Ca~(2+)concentration (≈10~(-6) mol/L, similar to thephysiological condition). If the transmembrane Ca~(2+) gradient was in the inverse direction (i.e. outside higher Ca~(2+) concentration, 0.5 mmol/L), a lowest enzymatic activity would appear. The difference in enzymatic activity between the two types of proteoliposomes could be diminished following the addition of Ca~(2+) ionophore A23187. Proteoliposomes without transmembrane Ca~(2+) gradient exhibited intermediate activities.The conformation difference of adenylatecyclases in the above-mentioned proteoliposomes was also detected by measuring intrinsic fluorescence and fluorescence quenching with KI.     

APPLICATIONS OF DSCPCF MODEL IN RARE EARTH COMPLEXES (Ⅳ)——ANALYSIS OF ABSORPTION SPECTRA FOR Pr~(3+)- AND Tm~(3+)-2-THENOYLTRIFLUOROACETONE-PIPERIDINE COMPLEXES

The new complexes, RE(TTA)_4·HP(RE are Pr~(3+) and Tm~(3+)), have been prepared, and their UV-VIS-NIR absorption spectra measured. All the matrix element formulas of f~2 and f~(12) configurations in D_4 symmetry field have been derived with the Double Sphere Coordination Point Charge Field Model, and the influence of the symmetry change of the complex unit, REO_3, on the forbital levels of Pr~(3+) is discussed. And based on the theoretical calculations, the transition peaks in the absorption bands are assigned.