检索结果-内蒙古大学图书馆

DIffERENCES IN THE SERUM-PROTEIN BINDING Of PRAZOSIN IN MAN AND RAT

BIOCHEMICAL PHARMACOLOGY 1984年第11期33卷 1719-1724页

作者： DALE, O NILSEN, OG Department of Pharmacology and Toxicology University of Trondheim School of Medicine Regional Hospital 7000 Trondheim Norway

The serum protein binding of prazosin in man and rat has been studied in vitro by equilibrium dialysis. Prazosin was more extensively bound in human serum than in rat serum with binding ratios (B/f) of 14.3 +/- 3.4 and 4.4 +/- 0.2 (corresponding to 93.4 and 81.4% bound), respectively. This difference in binding between the species was partly due to qualitative differences between human and rat serum albumin, but also to the lower concentration of albumin in rat serum. Rat serum albumin (RSA) apparently showed two different classes of binding sites for prazosin, one with high (KD = 5.78 X 10(-6) M) and one with low (KD = 1.1 X 10(-4) M) affinity; the former is suggested as representing alpha 1-acid glycoprotein (alpha 1-AGP) with one binding site for prazosin per molecule, the latter as representing RSA with 0.28 binding sites per molecule. Human serum albumin (HSA) and human alpha 1-AGP both showed one class of binding sites with KD values of 2.7 X 10(-5) and 1.95 X 10(-6) M, respectively. HSA possessed 0.5 and human alpha 1-AGP 1 binding site for prazosin per molecule. The binding parameters obtained for the isolated serum proteins overestimated to some degree the total serum protein binding of prazosin in man. This was explained by a specific deviation from the law of mass action. HSA was the major binding protein in human serum at therapeutic concentrations, with ca. 60% of the total binding, the remaining 40% being bound to alpha 1-AGP. Anticipating that the high affinity binding site on the RSA preparation represents the binding of prazosin to alpha 1-AGP, then this protein accounts for 70% of the binding in rat serum, while rat serum albumin accounts for approximately 23%. The binding of prazosin to lipoproteins was insignificant in both species. The observed differences between man and rat in the serum protein binding of prazosin implicate differences in the two species with respect to prazosin pharmacokinetics and the pharmacological effect.

关键词： HSA, human serum albumin RSA, rat serum albumin α 1 -AGP, α 1 -acid glycoprotein K D dissociation constant n , number of binding sites B , molarconcentration of bound prazosin f , molar concentration of unbound prazosin P , molar concentration of protein

来源：评论

学校读者我要写书评

暂无评论

fLUORESCENCE QUENCHING BY IODIDE-IONS Of LOW-DENSITY LIPOPROTEINS fROM NORMOLIPIDEMIC AND HYPERCHOLESTEROLEMIC TYPE-IIA SUBJECTS - EffECT Of LOW-DENSITY LIPOPROTEIN-CHOLESTEROL AND LOW-DENSITY LIPOPROTEIN NON-APOLIPOPROTEIN-B

引用

CHEMISTRY AND PHYSICS Of LIPIDS 1984年第2期36卷 121-130页

作者： DANG, QQ DOUSTEBLAZY, P CAMARE, R GALY, D CHU PURPAN CARDIOL CLIN F-31059 TOULOUSE FRANCE

To evaluate the effect of hypercholesterolemia on the surface properties of low density lipoproteins (LDL), the quenching by I ions of the native fluorescence of human plasma LDL was studied on normolipidemic and hypercholesterolemic type IIa subjects. A significant difference (P < 0.001) was found between these 2 groups (20 patients with type IIa hyperlipoproteinemia, 18 normolipidemic subjects). The fluorescence quenching (f0-f1)/f0 (f0 and f1 fluorescence intensity, respectively, in the absence and in the presence of I ions is negatively correlated with the relative LDL-cholesterol level (LDL-cholesterol/LDL-apoprotein [apo]). This quenching is positively correlated with the relative LDL-non-apo-B level (LDL-non-apo-B/LDL apo). Apparently, the greater the LDL-cholesterol level, the more embedded are the tryptophyl residues in the hydrophobic core. The greater the LDL-non-apo-B level, the more exposed are the tryptophyl to the aqueous environment. Thus, a significant conformation change of the superficial apolipoproteins occurs, which could affect the immunological properties of the LDL and their affinity of the LDL receptors.

关键词： Low density lipoprotein hypercholesterolemia type II 3 tryptophyl fluorescence quenching LDL-cholesterol LDL-non-apo-B interactions lipid-protein and protein-protein HDL high-density lipoprotein LDL low density lipoprotein HC hypercholesterolemic patients NL normolipidemic patients c LDL-cholesterol (mmol/l) p LDL-apoproteins (g/l) f 0 fluorescence intensity in 0.2 M NaCl f 1 fluorescence intensity in 0.2 M KI Apo apolipoprotein non-apo-B non-apolipoprotein-B

来源：评论

学校读者我要写书评

暂无评论

KINETICS Of METHOTREXATE BINDING TO DIHYDROfOLATE-REDUCTASE fROM NEISSERIA-GONORRHOEAE

引用

BIOCHEMICAL PHARMACOLOGY 1984年第13期33卷 2101-2107页

作者： BACCANARI, DP TANSIK, RL WELLCOME RES LABS RES TRIANGLE PK NC 27709 USA

The kinetics of methotrexate inhibition of dihydrofolate reductase from N. gonorrhoeae were investigated. Methotrexate was shown to be a tight-binding inhibitor (Ki = 13 pM) competitive with dihydrofolate. Stoichiometric or pseudoirreversible inhibition could not be demonstrated. Progress curves of inhibited assays quickly attained steady state regardless of the order of substrate addition, indicating that methotrexate association and dissociation processes were rapid. Kinetic techniques were used to measure the rate of methotrexate dissociation from the enzyme-NADPH-methotrexate ternary complex. At ***. C, the 1st-order off-rate constant (koff) was calculated to be 0.56 min-1. This value is .apprx. 40-fold greater than the dissociation rate constant of methotrexate for Escherichia coli dihydrofolate reductase. At lower temperatures, progress curves of methotrexate-inhibited gonococcal enzyme assays displayed marked increases in both curvature and the time to reach steady state. At ***. C, the methotrexate dissociation rate was slow enough (koff = 0.04 min-1) so that initial velocities of the reaction could be measured, and under these conditions methotrexate inhibition was shown to be stoichiometric.

关键词： I t total inhibitor (free + bound) E t total enzyme (free + bound) E free enzyme S free substrate I free inhibitor P product k n first- or second-order rate constants where odd numbers denote forward rates and even numbers reverse rates k on the second-order association rate constant for binding to the ternary complex k off the first-order methotrexate dissociation rate constant for the ternary complex K i the methotrexate dissociation constant of the ternary complex K s Michaelis constant v 0 reaction velocity in the absence of inhibitor v i reaction velocity in the presence of inhibitor t 1 2 halftime R f relative mobility

来源：评论

学校读者我要写书评

暂无评论

ELECTRON-TRANSfER BETWEEN THE 2 PHOTOSYSTEMS .2. EQUILIBRIUM-CONSTANTS

引用

BIOCHIMICA ET BIOPHYSICA ACTA 1984年第2期765卷 219-226页

作者： JOLIOT, P JOLIOT, A Institut de Biologie Physico-Chimique 13 rue Pierre et Marie Curie 75005 Paris France

The equilibrium constants for the redox reactions occurring between Photosystem (PS) I donors were measured on chloroplasts [spinach] dark-adapted in the presence of sodium ascorbate and 3-(3'',4''-dichlorophenyl)-1,1-dimethylurea (DCMU), and then illuminated by d.c. light. The equilibrium constant for the electron transfer between plastocyanin and P-700 is close to 1, and the overall equilibrium constant between cytochrome f and P-700 is .apprx. 2.3. As these equilibrium constants do not depend upon the intensity of the d.c. beam, the low values measured cannot be due to kinetic limitations. The equilibrium constants were measured also in the absence of DCMU using chloroplasts in oxidizing conditions (ferricyanide or far red illumination) illuminated by a saturating flash. During the course of the reduction of PS I donors by plastoquinol molecules formed by the flash, the equilibrium constants are higher than in the preceding conditions;the value for plastocyanin to P-700 is close to 5, and that for cytochrome f to P-700 is .apprx. 25. The variations of these equilibrium constants are tentatively interpreted as being due to mutual electrostatic interactions between cytochrome b and f which are included in the same complex. This model implies that the perturbation of the redox properties of cytochrome f by a positive charge located on cytochrome b is identical to the perturbation of the redox properties of cytochrome b by a positive charge located on cytochrome f.

关键词： Cytochrome f Plastocyanin P−700 Electron transfer Photosynthesis (Spinach chloroplast) PS Photosystem cyt f cytochrome f cytochrome b cytochrome b -563 PC plastocyanin DCMU 3-(3,′,4′-dichlorophenyl)-1,1-dimethylurea

来源：评论

学校读者我要写书评

暂无评论

INDEPENDENT EffECTS Of MAGNESIUM-IONS ON ENERGY-TRANSfER PROCESSES IN CHLOROPLASTS

引用

BIOCHIMICA ET BIOPHYSICA ACTA 1984年第2期766卷 303-309页

作者： JENNINGS, RC Centro C.N.R. Biologia Cellulare e Molecolare delle Piante Dipartimento di Biologia Università di Milano Via Celoria 26 20133 Milano Italy

The effect of removal of Mg 2+ on the fluorescence properties of LHCP-PS-II has been examined by different methods: (a) by titration with the artificial quenchers of chlorophyll fluorescence, m -dinitrobenzene and DBMIB (2,5-dibromo-3-methyl-6-isopropyl- p -benzoquinone); (b) as a function of wavelengths absorbed preferentially by LHCP, compared with wavelengths relatively enriched in PS II absorbed light; (c) by measurement of the fluorescence induction parameters as a function of the Mg 2+ concentration or the excitation wavelength (i.e., light absorbed preferentially by LHCP or relatively enriched in PS II absorbed wavelengths). The following conclusions are drawn. (a) In the presence of magnesium ions, energy-transfer coupling between LHCP and PS II is tight, which argues against the idea of a weakly coupled population of LHCP molecules. (b) On lowering the Mg 2+ concentration of a chloroplast suspension: (1) the increased spillover of energy to PS-I involves virtually all LHCP-PS-II entities and not just a part, which is strongly quenched; (2) there is a decrease in LHCP-PS-II energy-transfer coupling and this occurs only at low Mg 2+ concentrations (below 0.5 mM). This process therefore seems distinct from the spillover interaction; (3) the rate constant for energy transfer to PS-II reaction centers decreases and this seems independent of the decreased LHCP-PS-II energy coupling.

关键词： fluoresence Energy transfer Photosystem II Light-harvesting complex Mg 2+ (Spinach chloroplast) LHCP light-harvesting chlorophyll a b protein PS II the Photosystem II core complex PS I Photosystem I f m maximum fluorescence (all traps closed) f 0 non-variable fluorescence (all traps open) f v variable fluorescence ( f m − f 0 ) DCMU 3-(3′,4′-dichlorophenyl)-1,1-dimethylurea DBMIB dibromothymoquinone

来源：评论

学校读者我要写书评

暂无评论

MEMBRANE PHOSPHORYLATION LEADS TO THE PARTIAL DETACHMENT Of THE CHLOROPHYLL-A/B PROTEIN fROM PHOTOSYSTEM-II

引用

BIOCHIMICA ET BIOPHYSICA ACTA 1984年第2期767卷 321-325页

作者： TORTI, f GEROLA, PD JENNINGS, RC UNIV MILANO DIPARTIMENTO BIOL CNR CTR BIOL CELLULARE & MOLEC PIANTE I-20133 MILANO ITALY

The hypothesis that the chlorophyll fluorescence decline due to membrane phosphorylation is caused principally by the detachment and removal of LHCP [light-harvesting chlorophyll a/b protein] from the LHCP-PS [photosystem] II matrix is examined [in spinach chloroplasts]. When membranes are phosphorylated in the dark the following developments are demonstrated: the fluorescence decline is greater when excited by light enriched in wavelengths absorbed mainly by LHCP (475 nm) than when excited by light absorbed to a large extent also by the PS II complex (435 nm);titration with different artificial quenchers of chlorophyll fluorescence is unchanged after the phosphorylation-induced fluorescence decline;and the fv/fm [variable fluorescence/maximum fluorescence] ratio does not change after the phosphorylation-induced fluorescence decline. It is indeed principally LHCP that interacts with the quencher (PS I presumably). This interaction involves a small fraction of the total PS II-coupled LHCP, which becomes functionally detached from the LHCP-PS II matrix.

关键词： Membrane phosphorylation Chlorophyll fluorescence quenching Photosystem II Light-harvesting complex (Spinach chloroplast) LHCP light-harvesting chlorophyll a / b protein PS II the Photosystem II core complex PS I Photosystem I f m maximum fluorescence (all traps closed) f 0 nonvariable fluorescence (all traps open) f v variable fluorescence ( f m − f 0 ) DCMU 3-(3′,4′-dichlorophenyl)-1,1-dimethylurea DBMIB dibromothymoquinone Tricine N -[2-hydroxy-1,1-bis(hydroxymethyl)ethyl]glycine

来源：评论

学校读者我要写书评

暂无评论

A METHOD fOR TESTING THE SPECIfICITY Of INfLUENZA-A VIRUS-REACTIVE MEMORY CYTO-TOXIC LYMPHOCYTE-T (CTL) CLONES IN LIMITING DILUTION CULTURES

引用

JOURNAL Of IMMUNOLOGICAL METHODS 1984年第2期69卷 215-227页

作者： KEES, U KYNAST, G WEBER, E KRAMMER, PH DEUTSCH KREBSFORSCHUNGSZENTRUM INST DOKUMENTAT INFORMAT & STAT BIOSTAT ABT D-6900 HEIDELBERG FED REP GER

A system for determining the frequency and fine specificity of influenza A virus-immune memory cytotoxic T cell (CTL) clones from limiting dilution (LD) microcultures is described. Such experiments can only be performed by analyzing the clonal response of CTL from wells of replica plates containing fractions of 1 original plate when it has been ascertained that splitting is possible at the clonal level, and that each fraction of a microculture well gives an identical response on target cells infected with the stimulating virus. With these requirements fulfilled it was found that short-term CTL clones from LD microcultures from influenza A virus (A/X-31)-immune mice (C57BL/6) occur at a frequency of f = 1:546 to f = 1:6303. The effector cells carry the Lyt-2.2 marker and are specific for target cells infected with the immunizing virus (influenza virus A/X-31). They do not lyse Newcastle disease virus or herpes simplex virus-infected or NK (YAC) target cells.

关键词： limiting dilution culture frequency analysis fine specificity of CTL influenza A virus CML cell-mediated lysis Con A concanavalin A CTL cytotoxic T lymphocyte CTL-p CTL precursor f CTL-p frequency fCS fetal calf serum HA hemmagglutinin HC high controls HSV herpes simplex virus LC low controls, LD, limiting dilution MC minimum chi square ML maximum likehood MOI multiplicity of infection N neuraminidase NDV Newcastle disease virus P probability PfU plaque forming units s standard deviation TCGf T cell growth factor

来源：评论

学校读者我要写书评

暂无评论

fLUORESCENCE PROBES IN METASTATIC B-16 MELANOMA MEMBRANES

引用

BIOCHIMICA ET BIOPHYSICA ACTA 1984年第2期776卷 299-312页

作者： SCHROEDER, f UNIV MISSOURI SCH MED DEPT PHARMACOL COLUMBIA MO 65212 USA

fluorescence probe molecules, trans-parinaric acid and 1,6-diphenylhexatriene, were utilized to characterize the structure of plasma membranes, microsomes and mitochondria from B16 melanoma cells. High metastatic B16-f10 and low metastatic B16-f1 melanoma cell lines had markedly different membrane structures. The fluorescence polarization, fluorescence lifetime and limiting anisotropy of trans-parinaric acid were significantly lower (P < 0.05) in all 3 membrane fractions of the B16-f1 cell line than in the corresponding membranes of the B16-f10 cell line. These data indicated less restriction to rotational motion in the solid lipid domains of B16-f1 cell membranes preferentially sensed by trans-parinaric acid. The limiting anisotropy of both trans-parinaric acid and 1,6-diphenylhexatriene was significantly lower in the outer monolayer than the inner monolayer of the plasma of B16-f1 cells but not in B16-f10 cells. A breakpoint in Arrhenius plots of fluorescence near ***.-***. C indicated that presence of a phase separation that was assigned to the inner monolayer of the plasma membrane. However, no differences in this breakpoint temperature were noted between the B16-f1 and B16-f10 melanoma membranes. Thus, more fluid solid membrane domains and a distinct transbilayer fluidity difference were characteristic of plasma membranes from low metastatic B16-f1 melanoma cells in contrast to high metastatic B16-f10 melanoma cells.

关键词： fluorescence polarization Membrane structure Rotational relaxation time Lipid asymmetry Metastasis Melanoma (Plasma membrane) A absorbance CO absorbance-corrected fluorescence τ lifetime P polarization f fractional fluorescence X mole fraction R rotational relaxation rate r ∞ limiting anisotropy r steady-state anisotropy r 0 anisotropy in the absence of rotational motion TNBS trinitrobenzenesulfonic acid

来源：评论

学校读者我要写书评

暂无评论

PURIfICATION Of A HIGH MOLECULAR-WEIGHT MEMBRANE-PROTEIN BY fAST PROTEIN LIQUID-CHROMATOGRAPHY - THE ATPASE COMPLEX Of A THERMOPHILIC CYANOBACTERIUM

引用

JOURNAL Of BIOCHEMICAL AND BIOPHYSICAL METHODS 1984年第2期9卷 163-169页

作者： VANWALRAVEN, HS GRAVESEN, M KRAAYENHOf, R PHARMACIA NEDERLAND BV 3442 AA WOERDENNETHERLANDS

fast protein liquid chromatography (fPLC) with a strong anion-exchange (Mono Q) column is applied to the purification of a high molecular weight membrane protein. The ATPase complex of the thermophilic cyanobacterium Synechococcus 6716, partially purified by ammonium sulfate precipitation, was fractionated in the presence of the detergent octylglucoside. The ATPase complex containing fractions were eluted by a linear NaCl gradient at about 0.4 M and within 10 min. The fPLC fractions were analyzed for protein and pigment contents and by polypeptide composition. The purest fraction is essentially free of pigments and has a high specific ATP hydrolysis activity (about 1.6 mumol ATP X min-1 X mg protein-1) which is sensitive to N,N'-dicyclohexylcarbodiimide.

关键词： fast protein liquid chromatography anion-exchange monobead column detergent octylglucoside ATPase complex thermophilic cyanobacterium fPLC fast protein liquid chromatography f 1 the hydrophilic part of the ATPase complex f 0 the hydrophobic part of the ATPase complex DCCD N , N ′-dicyclohexylcarbodiimide DTE dithioerythritol SDS sodium dodecyl sulffate

来源：评论

学校读者我要写书评

暂无评论

USE Of THE EXPERIMENTWISE ERROR RATE IN SIMULTANEOUS TESTS Of MAIN EffECTS IN 2-WAY DISPROPORTIONATE ANOVA WITHOUT INTERACTION

引用

JOURNAL Of STATISTICAL PLANNING AND INfERENCE 1984年第2期9卷 155-162页

作者： MCALLISTER, PR HOLLAND, BS TEMPLE UNIV DEPT STAT PHILADELPHIA PA 19122 USA

It is argued that the probability of committing at least one type I error should be reported when testing the main effects simultaneously in a two-way disproportionate ANOVA without interaction. The circumstances where the two f -statistics depart appreciably from statistical independence are characterized, and it is pointed out that procedures now exist for evaluating the bivariate f -probabilities when required. The augmented analysis is illustrated with a numerical example and an extension is offered for assymmetric BIBD's with random block effects.

关键词： 62J10 62H10 Balanced incomplete block design Canonical correlations Jensen's bivariate f -distribution

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：