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The concentrations of n-butanol and tetracaine required for 50% inhibition of the ATPase activity of f1 particles isolated from bovine heart mitochondria were 160 mM and 1.1 mM, respectively. The physiological effects... 详细信息

关键词： f 1 -ATPase Anesthetic n -Butanol Tetracaine (Bovine heart mitochondria)

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PROPERTIES Of APOLIPOPROTEIN-B IN UREA AND IN AQUEOUS BUffERS - THE USE Of GLUTATHIONE AND NITROGEN IN ITS SOLUBILIZATION

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BIOCHIMICA ET BIOPHYSICA ACTA 1981年第1期666卷 133-146页

作者： LEE, DM VALENTE, AJ KUO, WH MAEDA, H UNIV OKLAHOMA DEPT BIOCHEM & MOLEC BIOL OKLAHOMA CITY OK 73104 USA

Based on the assumption that lipid peroxidation of low density lipoproteins (LDL) may be the main cause of the insolubility of the major protein moiety, apolipoprotein B, a procedure was developed which by minimizing possible oxidation conditions throughout the isolation, fractionation and delipidization of [human] LDL2 resulted in apolipoprotein B preparations totally soluble in 6 M urea and aqueous buffers. In addition to usual ***, antibiotics and protease *** procedure includes the use of antioxidant glutathione and N2. The LDL2 were delipidized wet with ethanol and diethyl ether, the latter being freed of peroxides before use. The LDL2 apolipoprotein obtained was solubilized totally in 6 M guanidine-HCl buffer containing the reducing agent dithiothreitol. After carboxymethylation the reduced and carboxymethylated (RCM) LDL2 apolipoprotein was purified by gel filtration to yield pure RCM apolipoprotein B. The latter was transferred to solution in 6 M urea by dialysis and further transferred to aqueous buffers, at lower protein concentrations. The solutions remained clear throughout. A possible key to the solubility of apolipoprotein B may lie in minimizing all potential sources of oxidation. RCM apolipoprotein B soluble in aqueous buffers was identical immunochemically and electrophoretically to the RCM apolipoprotein B soluble in 6 M urea. The RCM apolipoprotein B gave a single precipitin line at low protein concentrations (0.1-1 mg/ml) against specific antibodies and 2 precipitin lines at higher concentrations (2-4 mg/ml). The behavior of RCM apolipoprotein B on SDS-polyacrylamide gel electrophoresis was anomalous, the apparent MW varying inversely with the total acrylamide monomer concentration. On SDS-urea-polyacrylamide gel electrophoresis, it moved as a single band of constant Mr [relative MW], 260,000. On basic urea-polyacrylamide gel electrophoresis, RCM apolipoprotein B was apparently heterogeneous, displaying at least 2

关键词： Apolipoprotein B Antioxidant Nitrogen Aqueous buffer Glutathione LDL low density lipoproteins ( d 1.006-1.063 g / ml ) LDL 2 low density lipoproteins of d 1.032-1.043 g / ml , S f 6–7 for this study LP-B lipoprotein B family, consisting of only apolipoprotein B as its protein moiety HDL 3 high density lipoproteins of d 1.125-1.21 g/ml GdnHCl guanidine hydrochloride R reduced RCM reduced and carboxymethylated SDS sodium dodecyl sulfate CTC 2-carboxy-2, 5, 7, 8-tetramethylchroman-6-ol CETC 2-(3-carboxyethyl)2, 5, 7, 8-tetramethylchroman-6-ol DATD N , N ′-diallytartardiamide NEMA N -ethyl morpholine acetate anti-Cu 2+ -B anti-Cu 2+ -treated apolipoprotein B Cu 2+ -RCM-B Cu 2+ -treated reduced and carboxymethylated apolipoprotein B T total acrylamide monomer concentration C proportion of cross-linking agent of acrylamide BHA butylated hydroxyanisole BHT butylated hydroxytoluene

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PURIfICATION AND PROPERTIES Of fMET-TRANSfER RNAf DEACYLASE fROM ESCHERICHIA-COLI

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BIOCHIMICA ET BIOPHYSICA ACTA 1981年第2期656卷 240-245页

作者： IGARASHI, K MATSUNAKA, M KASHIWAGI, K MITSUI, K HIROSE, S CHIBA UNIV FAC PHARMACEUT SCI CHIBA 260 JAPAN

A formylmethionyl-tRNAf deacylase was purified .apprx. 330-fold from a crude initiation factor preparation (1 M NH4Cl ribosomal wash) from E. coli Q13. The enzyme was nearly homogeneous and had an apparent MW of 24,000. Rat liver methionyl-tRNAf and E. coli methionyl-tRNAm were not hydrolyzed significantly by the enzyme under standard conditions. Phage ***. RNA-directed and AUG(A)n-directed polypeptide synthesis was inhibited by the enzyme. The inhibition was at the level of initiation of polypeptide synthesis. The enzymatic activity was inhibited by various factors necessary for polypeptide synthesis. The activity was inhibited more by NH4Cl and spermidine than by Mg2+, GTP and ATP. The complex of formylmethionyl-tRNAf, initiation factor and GTP was resistant to enzymatic hydrolysis, and the resistance was enhanced by the addition of AUG and ribosomes to the above reaction mixture.

关键词： fMet-tRNA f deacylase Protein synthesis Initiation factor (E. coli) Hepes N-2- hydroxyethylpiperazine -N′-2- ethanesulfonic acid

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LIGHT-DEPENDENT QUENCHING Of CHLOROPHYLL fLUORESCENCE IN PEA-CHLOROPLASTS INDUCED BY ADENOSINE 5'-TRIPHOSPHATE

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BIOCHIMICA ET BIOPHYSICA ACTA 1981年第1期635卷 53-62页

作者： HORTON, P BLACK, MT UNIV SHEFFIELD DEPT BIOCHEM SHEFFIELD S10 2TN S YORKSHIRE ENGLAND UNIV SHEFFIELD ARC PHOTOSYNTH GRP SHEFFIELD S10 2TN S YORKSHIRE ENGLAND

Addition of ATP to chloroplasts causes a reversible 25-30% decrease in chlorophyll fluorescence. This quenching is light-dependent, uncoupler insensitive but inhibited by 3-(3,4-dichlorophenyl)-1,1-dimethyl urea (DCMU) and electron acceptors and has a half-time of 3 min. Electron donors to PS (photosystem) I cannot overcome the inhibitory effect of DCMU;apparently light activation depends on the reduced state of plastoquinone. fluorescence emission spectra recorded at -***. C indicate that ATP treatment increases the amount of excitation energy transferred to PS I. fluorescence induction curves indicate that ATP treatment decreases both the initial (f0) and variable (fv) fluorescence such that the ratio of fv to the maximum (fm) yield is unchanged. The initial sigmoidal phase of induction is slowed down by ATP treatment and is quenched 3-fold more than the exponential slow phase, the rate of which is unchanged. A plot of fv against area above the induction curve was identical plus or minus ATP. ATP treatment can alter quantal distribution between PS II and PS I without altering PS II-PS II interaction. The effect of ATP strongly resembles in its properties the phosphorylation of the light-harvesting complex by a light activated, ATP-dependent protein kinase found in chloroplast membranes and may be the basis of physiological mechanisms which contribute to slow fluorescence quenching in vivo and regulate excitation energy distribution between PS I and PS II. The sensor for this regulation may be the redox state of plastoquinone.

关键词： Chlorophyll fluorescence fluorescence quenching ATP effect Plastoquinone Exciton distribution PS II Photosystem II PS I Photosystem I f m maximum fluorescence level when all Photosystem II traps are closed f o minimum fluorescence level when all Photosystem II traps are open f v f m – f o DCMU 3-(3,4-dichlorophenyl)-1,1-dimethylurea Hepes N -2-hydroxyethylpiperazine- N ′-2-ethanesulfonic acid Tricine N -tris(hydroxymethyl)methylglycine LHC light-harvesting complex Q primary electron acceptor of Photosystem II

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INVOLVEMENT Of TETRAHYDROfOLATE COfACTORS IN DENOVO PURINE RIBONUCLEOTIDE SYNTHESIS BY ADULT BRUGIA-PAHANGI AND DIROfILARIA-IMMITIS

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MOLECULAR AND BIOCHEMICAL PARASITOLOGY 1981年第5-6期2卷 259-270页

作者： JAffE, JJ CHRIN, LR Department of Pharmacology College of Medicine University of Vermont Burlington VT 05405 U.S.A.

Adult B. pahangi in vitro, unlike mouse leukemia L1210 cells, converted 5-methyltetrahydrofolate (CH3fH4) directly to 5,10-methylenetetrahydrofolate and thence to other fH4 [tetrahydrofolate] cofactors. The excreted CO2 derived from CH3fH4 was due to the presence within the filariae of 10-formyltetrahydrofolate dehydrogenase (EC 1.5.1.6) which catalyzes the deformylation of 10-formyltetrahydrofolate. Adult B. pahangi and D. immitis, incubated in a purine-free medium containing [5-14C]CH3fH4 as the only form of folate, synthesized purine ribonucleotides radiolabeled at positions 2 and 8 of the purine ring. Presumably, 10-formyl[14C]fH4 donated Carbon 2 during the synthesis de novo of the purine ring and 5,10-methenyl[14C]fH4 donated Carbon 8.

关键词： Brugia pahangi Dirofilaria immitis folate metabolism Purine synthesis 5 10-Methyltetrahydrofolate oxidation fH 4 , tetrahydrofolic acid CH 3 fH 4 , 5-methyltetrahydrofolate TCA, trichloroacetic acid TLC, thin-layer chromatography f 10 fH 4 , 10-formyltetrahydrofolate HBSS, Hank's balanced salt solution

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THE PROLIfERATIVE STATE Of NORMAL HEMATOPOIETIC STEM-CELLS DURING PROGRESSION Of LEUKEMIA - STUDIES IN THE BN ACUTE MYELOCYTIC-LEUKEMIA (BNML)

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LEUKEMIA RESEARCH 1981年第2期5卷 141-148页

作者： HAGENBEEK, A MARTENS, ACM TNO INST RADIOBIOL POB 5815 2280 HV RIJSWIJK NETHERLANDS

The kinetics of proliferation of normal hemopoietic stem cells (HSC) were investigated during the course of leukemia in a rat model for human acute myelocytic leukemia (BNML). The fraction of stem cells in DNA synthesis phase was determined with the hydroxyurea suicide technique followed by modified spleen colony assays on bone marrow, blood and spleen cell suspensions. Besides a redistribution and an absolute numerical decrease in the total number of HSC (to 45% of the original number), the percentage of cycling HSC decreased significantly as the leukemia progressed. In the bone marrow the S-phase fraction of HSC decreased from 38% to almost zero. Proliferating stem cells are thought to emigrate from the blood and lodge at extramedullary sites. Proliferation of HSC is best preserved in the spleen (in the terminal stage: 32-53% in S-phase). Normal hemopoiesis is still insufficient and the rats die from the consequences of a lack of mature end cells. A possible mechanism underlying the changes and differences in kinetic behavior of HSC in the various organs studied is discussed.

关键词： AML acute myelocyte leukemia BN Brown Norway inbred rat strain BNML BN acute myelocytic leukemia CfU-c colony forming units-culture CfU-s colony forming units-spleen DNA deoxyribonucleic acid f the fraction of injected (L)CfU-S recovered from the spleen HSC pluripotent hemopoietic stem cell(s) 3 HTdR tritiated thymidine HU hydroxyurea i.p. intraperitoneal i.v. intravenous LCfU-s leukemic colony forming unit-spleen S-phase DNA synthesis phase of the cell cycle

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STUDIES Of THE KINETICS Of THE ISOLATED MITOCHONDRIAL ATPASE USING DINITROPHENOL AS A PROBE

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BIOCHIMICA ET BIOPHYSICA ACTA 1981年第2期635卷 412-428页

作者： HARRIS, DA DALLLARSEN, T KLUNGSOYR, L DEPT BIOCHEM N-5000 BERGEN NORWAY

Dinitrophenol and maleate anions increase VATP on the washed, isolated, mitochondrial ATPase. Hydrolyses of iso-GTP and 2''-deoxy ATP are also stimulated, while hydrolyses of other nucleoside triphosphates (ITP, GTP etc.) are not. Preincubation with ATP, iso-GTP or '' 2''-deoxy ATP results in a metastable enzyme form with a raised V and a reduced Km. Dinitrophenol stimulates both ATP and ITP hydrolyses by this form. The Arrhenius plot of ATP (but not ITP) hydrolysis by the isolated ATPase shows a break at about ***. C, apparently because the rate limiting step of hydrolysis changes as the temperature rises. Adenylyl .beta., .gamma.-imidodiphosphate (AdoPP[NH]P) inhibits ITP hydrolysis in a pseudofirst order reaction. Its binding is competitive with ITP. If the enzyme is preincubated with ATP, the rate of AdoPP[NH]P binding increases. AdoPP[NH]P probably inhibits by binding to the hydrolytic site of the enzyme. ATP hydrolysis is apparently limited by diphosphate release and ITP hydrolysis by bond splitting. Energy release during ATP hydrolysis is maximal at the ATP binding step, and during ITP hydrolysis at bond splitting.

关键词： f 1 -ATPase Dinitrophenol Nucleotide binding (Kinetics)

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SUBSTRATE-SPECIfICITY Of ALPHA-L-ARABINOfURANOSIDASE fROM PLANT SCOPOLIA-JAPONICA CALLUSES AND A SUGGESTION WITH REfERENCE TO THE STRUCTURE Of BEET ARABAN

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BIOCHIMICA ET BIOPHYSICA ACTA 1981年第2期658卷 377-386页

作者： TANAKA, M ABE, A UCHIDA, T MITSUBISHI KASEI INST LIFE SCI MACHIDA TOKYO 194 JAPAN

Substrate specificity of .alpha.-L-arabinofuranosidase from plant S. japonica was examined using 3 kinds of arabinodisaccharides prepared from natural sources or synthetically. This enzyme hydrolyzed arabinofuranosylarabinoses which had either on .alpha.-(1 .fwdarw. 3) or a .alpha.-(1 .fwdarw. 5) linkage but hydrolyzed arabinopyranosyl-arabinose having a .alpha.-(1 .fwdarw. 5) linkage to a lesser degree. .alpha.-L-Arabinofuranosidase (.alpha.-L-arabinofuranoside arabinofuranohydrolase, EC 3.2.1.55), which is an exo-enzyme, degraded beet araban incompletely. Arabinose oligomers and galactose-containing fragments, isolated following acid hydrolysis of araban, were incompletely degraded by the enzyme. The reasons for the incomplete degradation were explained by the novel finding of (1 .fwdarw. 2) linkages and arabinopyranosides and the inclusion of trace amounts of galactose into the carbohydrate chain of araban. This enzyme was practically non-reacting with the hydroxyprolyl-arabinose linkage of glycopeptides from plant cell walls.

关键词： α- l -Arabinofuranosidase Arabino-disaccharide Araban Substrate specificity Ara f (1 → 3)Ara α -arabinofuranosyl-(1 → 3)-arabinose Ara f (1 → 5)Ara α -arabinofuranosyl-(1 → 5)-arabinose Ara p (1 → 5)Ara α -arabinopyranosyl-(1 → 5)-arabinose

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