EMPLOYMENT OF SPIN TRAPPING TECHNIQUE TO THE STUDY OF PHOTOCATALYTIC DEHYDROGENATION MECHANISM OF ALCOHOL IN AQUEOUS SOLUTION

Spin trapping technique was employed to study the mechanism of photocatalyticdehydrogenation of alcohol during in situ irradiation of Rh_2O_3/CdS powder which is sus-pended in aqueous aicohol solution.Evidence for production of ·OH radical is presentedand the rate of·OH radical formation corresponds to the rate of H_2 evolution.On the ba-sis of the above results,it is suggested that water cleavage is an intermediate step in this reac-tion.     

THE ASSOCIATION OF VACCINIA VIRUS WITH INTERMEDIATE FILAMENT

The intermediate filament-lamina-nuclear matrix system (IF-lamina-Nm System) can be shown clearlyusing selective extraction, embedment-free electron microscopy and whole mount cell preparation. A del-icate intermediate filament network was demonstrated in vaccinia virus factory for the first time. It isa part of the cytoplasmic intermediate filament network. The components and substructures of vacciniavirus bind firmly to intermediate filaments. Both assembled and assembling vaccinia viruses are fixedin the intermediate filament network. Direct connections between viruses and intermediate filaments canbe observed. We propose that vaccinia virus assembly depends on intermediate filaments as support.     

SPECTROPHOTOMETRIC STUDIES OF THE IRON CATALYST SYSTEM USED FOR BUTADIENE POLYMERIZATION

Catalysts consistiug of different iron compounds, triisobutylaluminium and warious ligands containing nitrogen used for butadiene polymerization were investigated by UV-visible, infrared spectroscopy. Spectra obtained illustrate an exchange taking place between the acetylacetonyl group in Fe(acac)_3 and the isobutyl group in Al(i-Bu)_3. During the exchange iron was reduced to lower valence state and coordinated with dipyridine or phenanthroline forming an active intermediate complex. A correlation between the absorption strength of the active intermediate complex in the visible range and the activity of catalyst was established.     

THE KERATIN INTERMEDIATE FILAMENTLIKE SYSTEM IN THE PLANT MESOPHYLL CELLS

A delicate intermediate filament-like network of mesophyll cells was observed both in maize and tobacco, using selective extraction together with whole-mount cell preparation for electron microscopy. The filament of the network is about 10 nm in diameter. Further test using immuno-gold labeling with anti-keratin antibodies indicated that the component of the intermediate filament-like system was keratin-like protein. Such a keratin-like intermediate filament system existing in plant cells was demonstrated for the first time. Meanwhile, 3-nm size filaments and their connection with 10-nm filaments were also shown in maize and tobacco protoplasts.     

THE PHOSPHORYLATION SITE OF SNAKE MUSCLE FRUCTOSE 1,6-BISPHOSPHATASE AND ITS PHOSPHORYLATION CONDITIONS

From the tryptic digests of phosphorylated snake muscle FruP_(2ase), a phosphoryl peptide has beenisolated, its amino acid sequence was Gly-Ala-Gly-Ser-Arg and the phosphorylation site was consideredto be on the serine residue. Effectors of the enzyme such as FruP_2, F6P and AMP did not affect thephosphorylation. The effect of pH on phosphorylation was consistent with that on the activity of theenzyme. The activity of phosphorylated enzyme was slightly lower than that of the native enzyme, thisdifference in activities between the two forms of the enzyme increased with decreasing the substrateconcentration. Results further support that a phosphorylated intermediate is involved in the catalytic reac-tion of FruP_(2ase).     

A CONVENIENT SYNTHETIC ROUTE FOR THE SEX PHEROMONE OF THE ASIAN CORN BORER MOTH (Ostrinia furnaculis Guenée)

By hydroboration of 10-undecen-1-ol acetate, a new synthetic route for the sex phero-mone of the Asian corn-borer (Ostrinia furnacalis Guenee) was devised to shorten the origi-nal 5 steps to a 2 steps reaction. The E- and Z-12-tetradecen-1-ol acetates were obtainedseparately with a purity greater than 98%. The location of the double bond position was as-certained by capillary GC and GC-MS. The important intermediate 12-tetradecyn-1-ol was also obtained from 2-tridecyn-1-ol byusing a zipper reaction, then by methylation and aeetylation. The intermediate obtainedfrom 3 different routes were compared by GC and GC-MS spectra to be identical.     

THE ROUTE OF INCORPORATION OF NITROGEN ATOM INTO RIFAMYCIN DURING ITS BIOSYNTHESIS

In this paper, it was first shown that under various conditions of nitrogen supply therifamycin yield was positively correlated with the mycelial specific activity of glutaminesynthetase (GS), then the enhancing effect of glutamine, the product of GS, on rifamycin bio-synthesis was demonstrated with resting cell system. The stimulatory effect of glutaminewas more pronounced than that of glutamate, and not reduced by a GS specific inhibitor, DON.However, the increase in yield brought about by glutamate, and by asparagine was stronglyinhibited by this inhibitor. Glutamine-CO~(15)NH_2 and glutamato-α-~(15)NH_2 were synthesized andcompared for the incorporation of ~(15)N into rifamycin. It was found that the amide nitrogenwas incorporated to a much greater extent than the α-amino nitrogen, showing that glutaminewas a direct precursor of the nitrogen atom in rifamycin. In addition, synthesis of A-32(C_7N), an intermediate secreted by an inactive mutant rif 1, was also greatly stimulatedby glutamine, and the synthetic C_7N was found to be able to stimulate the biosynthesis ofrifamycin. Based upon the above results, the route of incorporation of nitrogen atom into rifamycinis summarized as follows:     

STUDY OF THE CATALYTIC TECHNOLOGY IN THE OXIDATIVE COUPLING OF METHANE

The temperature of the catalyst bed in the oxidative coupling ofmethane would rise and be higher than the wall temperature when the amountof catalyst, the space velocity and the ratio of oxygen to methane wereincreased. Various aspects of the catalytic technology including the thickness ofthe catalyst bed, the mode of catalyst charge, the ratio of CH_4 to O_2 and thespece velocity were studied. An optimum temperature of the catalyst bed forhigher methane conversion and C_2 selectivity was investigated. It was foundthat the burning of methane in the gas phase to form CO occurred at certaintemperatures with some ratios of oxygen to methane. Additionally, the effectof adding water to the reaction feed gas was studied.     

FREQUENCY DEPENDENCE OF THE DIELECTRIC RELAXATION OF 1,2-POLYBUTADIENES

The dielectric loss factor and permittivity of a series of 1, 2-polybutadienes with different contents of 1, 2-units and different contents of syndiotactie 1, 2-units were determined over a frequency range from 30Hz to 100KHz at different temperatures. The WLF equation was evaluated for various samples with T_θat 100KHz as a reference temperature and the master curves of various samples have been constructed, which are in accordance with those calculated by Havriliak-Negami equation. The frequency dependence of the dielectric relaxation of 1, 2-polybutadienes was investigated over a frequency range from 10~0 Hz to 10~(12) ZHz in terms of the experimental data and the master curves.     

PHOSPHORYLATED REACTION OF SNAKE MUSCLE FRUCTOSE 1,6-BISPHOSPHATASE IN ITS REVERSE REACTION

A phosphoryl enzyme intermediate was observed in the hydrolysis of FruP_2 catalyzed by snake muscleFruP_(2ase) based on the fact that the formation rate of F6P is faster than that of inorganic phosphatewhen the reaction mixture contains a phosphoryl acceptor other than water. A covalently bound phosphateon the enzyme was isolated from the reverse reaction. This intermediate may relate to the process of theforward catalytic reaction by the enzyme.     

DIRECT CONVERSION OF METHANE TO METHANOL——THE EFFECT OF SENSITIZERS ON THE YIELD OF METHANOL AND THE KINETIC STUDY

The partial oxidation of methane to methanol was studied. The effectof various homogeneous "sensitizers" on the oxidation of pure methane was e-valuated at 433℃ and under a pressure of 5.0MPa. It was found that CH_3NO_2was the best one among them. A kinetic study in the presence of CH_3NO_2 wascarried out and the reaction mechanism was discussed.     

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.     

THE PROTEIN SUBUNITS OF THE DOUBLESTRANDED RNA DEPENDENT RNA POLYMERASE AND METHYLTRANSFERASE OF THE CYTOPLASMIC POLYHEDROSIS VIRUS OF SILKWORM, Bombyx mori

The particles of CPV of silkworm contain double-stranded RNA polymerase and methyltransferase. It was reported in a previous paper that the genome-enzyme complex could be isolated. The genome-enzyme complex shows high enzyme activity of RNA polymerase and methyltransferase in spite of the fact that it consists of only 5 percent of the protein. In order to clarify the protein subunits of the RNA polymerase and methyltransferase, two methods were adopted. The SDS-polyacrylamide gel electrophoretogram showed that the ~(125)I-labeled genome-enzyme complex of CPV contained three protein components in molccular weight of 33 K, 67 K and 142 K daltons respectively and each protein component of them consisted of more than two protein subunits with different isoelectric points in 2-dimensional electrophoretogram. The antibody to the five protein components (P1, P2, P3, P4, P5) was prepared and used to inhibit the enzyme activities of RNA polymerase and mthyltransferase. It showed that the RNA polymerase was inhib     

PHOTOPHYSICS STUDIES OF ORCANIC COMPOUNDS (Ⅻ)——THE INVESTIGATION OF THE FLUORESCENCE SPECTRA OF N-SALICYLIDENE-p-(N,N-DIMETHYLAMINO)ANILINE

The fluorescence spectra of N--salicylidene-p-(N,N--dimethylamino)aniline have beeninvestigated in various solvents. Three kinds of fluorescence have been found in the solutionsof various concentrations. They are the excited intermediate (EI) which is formed when theproton transfer has occurred but essentially retains the geometry of the enol tautomer, theexciplex (EX) which consists of a ground monomer and an excited state intermediate and theexcited dimer (ED) which is caused by ground state aggregate. The fluorescence lifetimesof the fluorophores have been measured in tetrahydrofuran (THF). Luminescent mechanismhas been discussed based on the fluorescence spectra and the kinetic data of the compound.     

STUDY ON THE EFFECT OF POLYSTYRENE SULFONIC ACID MACROMOLECULES ON THE POLYMERIZATION OF ACRYLAMIDE

The effect of polystyrene sulfonic acid (PSSA) macromolecules on the polymerization of acrylamide (AM) has been studied. It was found that the rates of polymerization of AM were greatly increased in the presence of PSSA in the polymerization system.The maximum value of the rate of polymerization of AM was obtained when the ratio of [—SO_3H]: [AM] reached 3:1. When the insoluble crosslinked PSSA was used instead of the soluble one, this effect decreased considerably. The interaction between molecules of PSSA and AM was determined by infrared spectroscopy, elementary analysis and X-ray photoelectron spectroscopy. The combination form, —SO_3-NH_3~ CO—, formed between sulfonic group and amide group was found to be existed since the infrared absorption band of —NH_2 shifted from 3400cm~(-1) to 3150 cm~(-1), the binding energy of electron N_(18) changed from 399.7 eV to 401.3 eV, and the atomic ratio of N to S of the products was similar to the ratio of reagents. Based on these experimental results, the mechanism of AM polymerization in the presence of PSSA is proposed. The initial step is the combination of AM with sulfonic group to form —CONH_3~ , then followed by polymerization on the PSSA macromolecule. The role of PSSA on the polymerization of AM is discussed.     

FORMATION AND DYNAMIC CHANGE OF INTERMEDIATES DURING THE SYNTHESIS OF LOWER ALCOHOLS

By means of the in silu IR spectroscopy fast response technique for apulse of gas,the formation and dynamic change of the intermediates on the cat-alyst surface during the synthesis of lower alcohols from CO+H_2 have beenstudied.The intermediates,such as HCOM(1715cm~(-1)),(1670cm~(-1)),HCOOM(1590,1382cm~(-1)),CH_3COM(1730cm~(-1))andCH_3COOM(1563,1434cm~(-1))were detected by IR.It was found that HCOMis the initial intermediate and can be transformed into,the growthof carbon chain is realized by the reaction of HCOM or HCOwith theadsorbed CO and H.HCOOM and CH_3COOM are not the main intermediates inthis expermental conditions.     

ELECTROFUSION OF IBRS2 CELLS AND THE STUDY OF THEIR FUSION PROCESS

IBRS2 epithelial cells in monolayer culture fused at a very high frequency when exposed to high-voltage electric pulsing fields. Exposure to four repetitive electric pulses of about 1.7 kilovolts per centimeter with a duration of 100 microseconds caused more than 90 percent of the cells to become fused (multinucleate) when 1 millimolar magnesium was present in the pulsing medium. Magnesium and calcium ions in the pulsing medium had a very strong effect on the electrofusion of IBRS2 cells. Magnesium could increase not only the electrofusion yield but also the stability of the cells under the conditions of electrofusion. In contrast, calcium inhibited electrofusion and decreased the stability of the cells. Careful microscopic observation revealed the electrofusion of IBRS2 cells to be very complex, dynamic process undergoing many interesting changes. A possible explanation for the process and mechanism of electrofusion of IBRS2 cells was proposed in agreement with the experimental observation.     

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.     

CHEMICAL MODIFICATION OF THE SURFACE OF CALCIUM ALGINATE GEL BEADS

The chemical modification of the surface of calcium alginate gel beads (CAGB) via grafting copolymerization with vinyl acetate (VAc) was studied. The optimum reaction conditions with activation and graft copolymerization two steps were explored. First, 5 grams CAGB with 2.5 mm initial diameter was initiated with 0.0493 mol/L K2S208 at 51℃ for 30 min in 15 mL 1% PVA/H2O. Then 4.34 mol/L VAc was added dropwise and the reaction was allowed to proce at 48℃ for 3 h. The grafting efficiency could come up to 30%. It was found the stability of modified CAGB in the air and in electrolyte solutions was greatly improved.     

THE ANTISENSE C-HA-RAS OLIGODEOXY-NUCLEOTIDES INHIBIT THE PROLIFERATION OF THE GASTROCARCINOMA-DNA-TRANSFORMED RAT 3-3 CELLS AND REDUCE THE P21 EXPRESSION OF THE CELLS

The Rat 3-3 is a secondary transformant of the rat fibroblast cell line (Rat-1) transfectedwith total DNA of a gastrocarcinoma cell line BGC-823. The cells over-express the c-Ha-rasoncogene which contains point mutation at the 12th codon. In order to determine how theactivated c-Ha-ras oncogene expression governs the cell's transformation, two pendadecadeoxy-nucleotides AS-1 and AS-2 were synthesized. AS-1 was complementary to the single strandof the first three codons and the upstream sequence close to the ribosome binding site of c-Ha-ras mRNA. AS-2 was complementary to the 3' end of the first intron and the 5' end ofthe second exon of c-Ha-ras unripe RNA enclosed in the nucleus. The oligonucleotides couldblock either the translation of c-Ha-ras mRNA or the splicing of c-Ha-ras unripe RNA, thusinhibiting the expression of the activated c-Ha-ras oncogene and the proliferation of thetransformed cells Rat 3-3. The inhibitory effect increased with a growing concentration ofthe antisense oligodeoxynucleoti