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DIPHASIC TRANSfORMATIONS Of f-ACTIN - EffECTS Of UREA AND MGCL-2 ON f-ACTIN

BIOCHIMICA ET BIOPHYSICA ACTA 1976年第1期427卷 126-140页

作者： TANIGUCHI, M NAGOYA UNIV FAC SCIDEPT PHYSNAGOYA 464JAPAN

Asakura, Taniguchi and Oosawa [1] proposed that muscle actin polymer under sonic vibration is in a different state from that of the ordinary double stranded helical structure (f-actin), characterised by partially interrupted structures of f-actin, a state of “f-actin”. In order to confirm different states for actin polymers [1, 2], physicochemical studies were made by measurements of viscosity, flow birefringence, electric birefringence, fluorescence, electron microscopy, quasielastic light scattering and ATP splitting. The following results were obtained. 1. (1) f-actin polymers can undergo two processes of depolymerization upon treatment with urea and various salts as judged by measurements of flow birefringence and viscosity: one is a rapid process in a solution containing K 1 or Ca 2+ and urea; the other is a slow process following a brief rapid one in a solution containing Mg 2+ and urea. 2. (2) In the presence of Mg 2+ and a suitable concentration of urea, f-actin (f mu -actin) appeared to exhibit different properties than ordinary f-actin; it had lower viscosity and lower flow birefringence and it had on the whole a more flexible polymer structure, also judging from experiments of quasielastic light scattering, electric birefringence. The different structure was confirmed directly by electron microscopic observation. The aromatic side chains of f mu -actin were also more mobile than those of f-actin judging from fluorescence measurements. The transformation between f-actin and f mu -actin was reversible. 3. (3) The state of f mu -actin polymers was also characterized by ATP splitting; f mu -actin split about one mole of ATP into ADP and inorganic phosphate per mole of actin monomer at room temperature, where f-actin did not. A molar excess of Mg 2+ with respect to actin monomer is required for ATP splitting. f-actin in solutions containing K + or Ca 2+ and urea did not split ATP. f mu -actin activated on Mg•ATPase of myosin at nearly the same rate as that of

关键词： f mu -actin in a solvent of 60 mM KCl 10 mM Tris•HCl buffer (pH 8.3) 0.4 mM ATP 2–3 mM MgCl 2 and 2 M < urea concentration < 4 M

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INTERACTION Of NUCLEOTIDE-DEPLETED f1-ATPASE WITH ADP - CHARACTERIZATION Of A HIGH-AffINITY BINDING-SITE RESPONSIBLE fOR ADP-INDUCED INHIBITION

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BIOCHIMICA ET BIOPHYSICA ACTA 1989年第1期975卷 50-58页

作者： MILGROM, YM MURATALIEV, MB A.N. Belozersky Laboratory of Molecular Biology and Bioorganic Chemistry Moscow State University Moscow (U.S.S.R.)

The ADP-induced inhibition of nucleotide-depleted f1-ATPase (ndf1-ATPase) from bovine heart mitochondria has been shown to be the result of ADP binding at one site with a dissociation constant of 4-5 nM. ADP binding at this site is at least biphasic: the initially formed complex (ADP .cntdot. ndf1) dissociating with the rate of about 0.01 s-1 is transformed with a half-time of 2-3 min to another state (ADP .cntdot. ndf1*) with the ADP-release rate of about 4 .cntdot. 10-4 s-1. ATP and ADP were found to accelerate the dissociation of ADP from the inhibitory site;half-maximal effects were exerted by 170 .mu.M ATP and 120 .mu.M ADP. The ATP-dependent reactivation of the inactive complex of ndf1-ATPase and ADP is suggested to result from the ATP-induced shift of the equilibrium between the ADP .cntdot. ndf1 and ADP .cntdot. ndf1* complexes to the former one. The nature of the inhibitory ADP-binding site is finally discussed, and it is concluded that this ADP-binding site is clearly distinct from the catalytic sites participating in the normal turnover of the enzyme.

关键词： ATPase, f 1 - ADP binding, high affinity Inhibitory site Nucleotide binding (Bovine heart mitochondria) f 1 -ATPase a catalytic component of the proton-translocating ATPase complex from bovine heartmitochondria (EC 3.6.1.34) pyruvate kinase (EC 2.7.1.40) lactate dehydrogenase (EC 1.1.1.27) ndf 1 -ATPase, f 1 -ATPase depleted from tightly bound nucleotides BSA bovine serumalbumin P i inorganic phosphate

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Iron Modification of Biochar Developed from Tectona grandis Linn. f. for Adsorptive Removal of Tetracycline from Aqueous Solution

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ANALYTICAL CHEMISTRY LETTERS 2021年第3期11卷 360-375页

作者： Srivastava, Anushree Dave, Hemen Azad, Shivesh Kumar Kumari, Madhu Karwal, Sharad Karma, Pooja Tiwari, Prabhuti Prasad, Kumar Suranjit Gujarat Forens Sci Univ GFSU Inst Res & Dev Gandhi Gandhinagar Gujarat India BRA Bihar Univ Dept Bot Muzaffarpur Bihar India Consortium Sci Res UGC Dept Atom Energy Indore India Devi Ahilaya Vishwavidyalaya Sch Instrumentat Indore India Maharaja Sayajirao Univ Baroda Fac Sci Dept Geol Vadodara India Univ Allahabad Inst Interdisciplinary Studies Ctr Environm Sci Allahabad Uttar Pradesh India

Iron-modified biochar was prepared using woody biomass of Tectona grandis Linn f. for the removal of tetracycline from an aqueous solution. The prepared biochar was characterized by fourier transformed infra-red spectroscopy, Scanning electron microscope, and X-ray photoelectron spectroscopy. The fTIR results showed predominant peaks that confirm the alignment of iron oxide on the surface of the biochar. Similarly, the surface of the iron-modified biochar constitutes a graphite sheet-like structure with irregular projection and peaks fit by XPS further provided evidence for the successful establishment of iron on the surface. The adsorption experiment was subjected to different equilibrium models namely Langmuir freundlich and Temkin, where Langmuir was found to be best fitted for adsorption. The maximum adsorption capacity was found to be 62.5 mg g(-1) at optimal experimental conditions. Pseudo second order with a better correlation coefficient (R-2=0.985) and rate constant (k =0.021) supported the chemical sorption hypothesis of tetracycline on biochar. The adsorption mechanism is well explained by the results obtained which supports surface interaction between biochar and tetracycline (TC). The thermodynamic parameters revealed that the process of adsorption was spontaneous and feasible (& UDelta;G & DEG;<0) while the reaction was found to be endothermic (& UDelta;H & DEG;=152.2J mol(-1)) where randomness (& UDelta;S & DEG;=60.88J mol(-1)) increases at the solid-liquid interface.

关键词： Tectona grandis Linn f Tetracycline Antibiotics fTIR SEM EDAX XPS Adsorption Biochar

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Cytotoxic and larvicidal activities of Stemona alkaloids from the aerial parts and roots of Stemona curtisii Hook.f.

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NATURAL PRODUCT RESEARCH 2021年第22期35卷 4311-4316页

作者： Chalom, Sirinrat Panyakaew, Jukreera Phaya, Manlika Pyne, Stephen G. Mungkornasawakul, Pitchaya Chiang Mai Univ Fac Sci Environm Sci Res Ctr PhD Degree Program Environm Sci Chiang Mai Thailand Chiang Mai Univ Fac Sci Dept Chem Chiang Mai 50200 Thailand Univ Wollongong Sch Chem & Mol Biosci Wollongong NSW Australia Chiang Mai Univ Fac Sci Dept Chem Ctr Excellence Innovat Chem Chiang Mai Thailand Chiang Mai Univ Fac Sci Environm Sci Res Ctr Chiang Mai Thailand

A new Stemona alkaloid glycoside derivative, 6-hydroxy-5,6-seco-stemocurtisinoside (4), was isolated from the ethanolic extract of the aerial parts of Stemona curtisii Hook.f., together with stemocurtisine (1), (11Z)-1',2'-didehydrostemofoline (2) and 6-hydroxy-5,6-seco-stemocurtisine (3). Whereas, stemocurtisine (1), stemocurtisinol (5) and oxyprotostemonine (6) were isolated from the roots. Their structures were elucidated using 1D and 2D NMR spectroscopy as well as MS experiments. The extract and the pure isolated compounds were evaluated for their cytotoxicities and their larvicidal activities against the dengue vector, Aedes aegypti. The alkaloid 2 showed the strongest larvicidal activity with a LC50 value of 2.44 mu M. While the alkaloid 3 exhibited cytotoxicity against MCf-7 and KB cells (IC50 values of 62.52 and 18.82 mu M, respectively) and showed no significant cytotoxicity against Vero cells. Additionally, quantitative analysis of the most active compounds;2 and 3 in the crude extracts was also performed by HPLC.

关键词： Stemonaceae Stemona curtisii Hook f Stemona alkaloids Cytotoxicity Larvicidal activity MCf-7 cells KB cells

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ON THE INTERACTION BETWEEN CYTOCHROME-f AND PLASTOCYANIN

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BIOCHIMICA ET BIOPHYSICA ACTA 1989年第1期975卷 158-163页

作者： ADAM, Z MALKIN, R UNIV CALIF BERKELEY DIV MOLEC PLANT BIOL 313 HILGARD HALL BERKELEY CA 94720 USA

The interaction between cytochrome f and its electron acceptor plastocyanin (PC) was studied. To address the question of which specific regions and which of the positively charged residues of cytochrome f are important for the interaction with the negatively charged residues of PC we have used two different experimental approaches. Cytochrome f was proteolytically cleaved and fragments that could bind to a PC-affinity column were isolated. The smallest of these fragments was analysed to give information on the minimum structural requirement for binding to PC. By this procedure, we identified a peptide of approx. 11 kDa, containing the heme binding site, and having an N-terminal sequence identical to that of the mature cytochrome f. This finding suggests that the first 90 amino acids of cytochrome f contain at least some of the residues interacting with PC. The second approach involved modification of Arg residues of cytochrome f with the specific chemical modifier, hydroxyphenylglyoxal (HPG). Cytochrome f modification was performed in the absence of PC to enable identification of residues that are protected from modification when PC is bound to cytochrome f. Two peptides containing ARg residues which are modified in the absence of PC, but are not modified when PC is present, were isolated. Sequence analysis of these two peptides revealed that Arg residues no. 88 and 154 of cytochrome f are the residues that are protected from modification when cytochrome f is bound to PC, suggesting a role for these residues in the binding of cytochrome f to PC.

关键词： Cytochrome f Plastocyanin Electron transport Chemical modification HPG hydroxyphenylglyoxal PAGE polyacrylamide gel electrophoresis PC plastocyanin PS I Photosystem I SDS sodium dodecyl sulfate TfA trifluoroacetic acid

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Prostaglandin f₂ Synthase Activities of AldoKeto Reductase 1B1, 1B3 and 1B7

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JOURNAL Of BIOCHEMISTRY 2009年第2期145卷 161-168页

作者： Kabututu, Zakayi Manin, Michele Pointud, Jean-Christophe Maruyama, Toshihiko Nagata, Nanae Lambert, Sarah Lefrancois-Martinez, Anne-Marie Martinez, Antoine Urade, Yoshihiro Osaka Biosci Inst Dept Mol Behav Biol Osaka 5650874 Japan Univ Clermont CNRS UMR Genet Reprod & Dev 6247 F-63177 Aubiere France

Here, we show that three enzymes belonging to the 1B group of the aldoketo reductase (AKR) superfamily, i.e., human placental aldose reductase (AKR1B1), mouse kidney aldose reductase (AKR1B3) and mouse vas deferens protein (AKR1B7), catalyse the reduction of prostaglandin (PG) H-2, a common intermediate of various prostanoids, to form PGf(2) in the presence of NADPH. AKR1B1, AKR1B3 and AKR1B7 displayed higher affinities for PGH(2) (K-m 1.9, 9.3 and 3.8 M, respectively) and V-max values (26, 53 and 44 nmol/min/mg protein, respectively) than did the human lung PGf(2) synthase (AKR1C3;18 M and 4 nmol/min/mg protein, respectively). The PGf(2) synthase activity of AKR1B1 and AKR1B3 was efficiently inhibited by two AKR inhibitors, tolrestat (K-i 3.6 and 0.26 M, respectively) and sorbinil (K-i 21.7 and 0.89 M, respectively), in a non-competitive or mixed-type manner, whereas that of AKR1B7 was not sensitive to these inhibitors (K-i 9.2 and 18 mM, respectively). These data provide a molecular basis for investigating novel functional roles for AKR1B members and PGf(2) as mediators of physiological and pathological processes in mammalian organisms.

关键词： Prostaglandins f Activities Minute of time nmol f

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Effect of prostate volume on f/tPSA value: A cross-sectional study

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ANDROLOGIA 2021年第2期53卷 e13851-e13851页

作者： Xu, Xin-He Xu, Zhi-He Yuan, Ming-Zhen Guan, Yong Zhao, Sheng-Tian Shandong Univ Sch Clin Med Jinan Peoples R China Shandong Prov Hosp Dept Urol 324 Jingqiweiwu Rd Jinan 250021 Shandong Peoples R China Shandong Univ Dept Urol Hosp 2 Jinan Peoples R China

Previous studies have suggested that there is a positive correlation between prostate-specific antigen (PSA) levels and prostate volume (PV). A better understanding of the possible influence of PV on a ratio of free to total PSA (f/tPSA) may improve the diagnostic value of the prostate disease. The study group consisted of 342 men with lower urinary tract symptoms (LUTS). All patients underwent urinary tract ultrasonography and had tests carried out on PSA, serum glucose, total cholesterol, triglyceride, HDL, LDL and blood pressure. Univariate and multivariate analyses were used to assess the associations between prostate volume and f/tPSA value. We found no obvious relationship between prostate volume and f/tPSA value when PSA >10 ng/ml but did observe a positive correlation when 4 ng/ml < PSA >10 ng/ml (hazard ratio [HR]: 0.0012;95% confidence interval [CI]: 0.0009-0.0248). With increasing prostate volume, multivariate analysis showed an obvious increase in f/tPSA value (HR: 0.0011;95% CI: 0.0007-0.0015) (p <= .0001). We confirmed that prostate volume could affect the f/tPSA levels in serum. There was an obvious positive correlation between prostate volume and f/tPSA level when PSA levels were between 4 and 10ng/dl. There was no significant correlation between prostate volume and f/tPSA value when PSA >10 ng/ml.

关键词： f tPSA fPSA prostate cancer prostate volume tPSA

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CHARACTERIZATION Of A PHOTOSYNTHETIC MUTANT Of LEMNA LACKING THE CYTOCHROME-B6-f COMPLEX

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BIOCHIMICA ET BIOPHYSICA ACTA 1985年第1期810卷 106-109页

作者： LAM, E MALKIN, R UNIV CALIF BERKELEY DIV MOLEC PLANT BIOL 313 HILGARD HALL BERKELEY CA 94720 USA ROCKEFELLER UNIV PLANT MOLEC BIOL LAB NEW YORK NY 10021 USA

A photosynthetic mutant of Lemna perpusilla (no. 1073) has been examined by spectrophotometric and immunoblotting techniques in order to localize the site of defect. In contrast to previous conclusions (Shahak, Y., Posner, H.B. and Avron, M. (1976) Plant Physiol. 57, 577-679), neither cytochrome f nor cytochrome b6 could be detected spectrophotemetrically in the mutant. furthermore, immunoblotting using antibodies specific for each of the four constituent subunits of the cytochrome b6-f complex demonstrate that the entire complex is absent in the mutant. The light-harvesting chlorophyll-protein complex of Photosystem II is present in similar amounts in wild-type and mutant Lemna. However, the total amount of plastoquinone-9 is reduced by approx. 65% in the mutant strain, while the photoreducible plastoquinone-9 pool is comparable in wild-type and mutant Lemna.

关键词： Photosystem II Chlorophyll-protein complex Cytochrome b 6 - f complex Plastoquinone ( Lemna ) LHCP II light-harvesting chlorophyll-protein complex of Photosystem II Cyt cytochrome Chl chlorophyll

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STEADY-STATE KINETICS Of f1-ATPASE - MECHANISM Of ANION ACTIVATION

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fEBS LETTERS 1985年第1期192卷 123-127页

作者： ROVERI, OA CALCATERRA, NB NATL UNIV ROSARIO RA-2000 ROSARIOARGENTINA

The kinetic behaviour of the ATPase activity of beef heart f1 depends largely on the exposure of the enzyme to some anionic ligands such as sulphate and/or EDTA. f1 prepared in the presence of such anions exhibited a triphasic kinetic pattern whereas f1 from which those anions were removed by dialysis exhibited only two Km values for ATP. Conversely to what has been previously reported, bicarbonate did not linearize f1-ATPase kinetics. Moreover, anion activation cannot be simply explained by promotion of ADP release but mainly by an increase in affinity of the third catalytic site for ATP.

关键词： f 1 -ATPase Mitochondrial ATPase Anion activation Hysteretic enzyme Steady-state kinetics (Beef heart)

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REGULATION Of PROTEIN-SYNTHESIS IN RABBIT RETICULOCYTE LYSATES BY HEME-REGULATED PROTEIN-KINASE - INHIBITION Of INTERACTION Of MET-TRANSfER-RNA-f(MET) BINDING fACTOR WITH ANOTHER INITIATION-fACTOR IN fORMATION Of MET-TRANSfER-RNA-f(MET).40S RIBOSOMAL-SUBUNIT COMPLEXES

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PROCEEDINGS Of THE NATIONAL ACADEMY Of SCIENCES Of THE UNITED STATES Of AMERICA 1978年第2期75卷 745-749页

作者： RANU, RS LONDON, IM DAS, A DASGUPTA, A MAJUMDAR, A RALSTON, R ROY, R GUPTA, NK HARVARD UNIV MIT DIV HLTH SCI & TECHNOL CAMBRIDGE MA 02139 USA HARVARD UNIV SCH MED DEPT MED BOSTON MA 02115 USA UNIV NEBRASKA DEPT CHEM LINCOLN NE 68588 USA

Protein synthesis in reticulocytes and their lysates is regulated by heme. In heme deficiency a heme-regulated translational inhibitor (HRI) that blocks initiation of polypeptide chains is activated. HRI is a protein kinase (ATP: protein phosphotransferase, EC 2.7.1.37) that specifically phosphorylates the 38,000 dalton subunit of the Met-tRNAfMet binding factor (If), which forms a ternary complex with Met-tRNAfMet and GTP, a finding that suggests that the inhibition by HRI involves the phosphorylation of If. The effect of HRI in the partial reactions of protein chain initiation in which the If-promoted binding of Met-tRNAfMet to 40S ribosomal subunits is enhanced by another initiation factor [ternary complex dissociation factor (TDf)] and AUG was investigated HRI at very low concentrations markedly inhibits the bindings of Met-tRNAfMet to 40S subunits. The inhibitory effect of HRI requires ATP. Under these conditions HRI phosphorylates only the 38,000 dalton subunit of If The TDf preparations not only promote the binding of the ternary complex to 40S subunits but also promote the dissociation of the ternary complex in the presence of 5 mM Mg2+ at ***. C. The preincubation of purified If alone with low concentrations of HRI and ATP does not significantly affect its capacity to form the ternary complex;however, the TDf-promoted dissociation of the ternary complex is inhibited. The nonhydrolyzable analog adenosine 5''[.beta..gamma.-imido]triphosphate does not substitute for ATP. Phosphorylation apparently causes a conformational modification in If, which results in inhibition of the interaction between the ternary complex and TDf that is required for the binding of the ternary complex to 40S subunits.

关键词： phosphorylation of Met-tRNA f Met binding factor translational regulation inhibition of Met-tRNA f Met binding 40S ribosomal subunits protein—protein interaction

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