The polar nature of 7-ketocholesterol determines its location within membrane domains and the kinetics of membrane microsolubilization by apolipoprotein A-I.


:7-Ketocholesterol is an oxidized derivative of cholesterol with numerous physiological effects. In model membranes, 7-ketocholesterol and cholesterol were compared by physical measures of bilayer order and polarity, formation of detergent resistant domains (DRM), phase separation, and membrane microsolubilization by apolipoprotein A-I. In binary mixtures of a saturated phosphatidylcholine (PC), dipalmitoyl-PC (DPPC), and cholesterol or 7-ketocholesterol, the sterols modulate bilayer order and polarity and induce DRM formation to a similar extent. Cholesterol induces formation of ordered lipid domains (rafts) in tertiary mixtures with dioleoyl-PC (DOPC) and DPPC, or DOPC and sphingomyelin (SM). In tertiary mixtures, cholesterol increased lipid order and reduces bilayer polarity more than 7-ketocholesterol. This effect was more pronounced when the mixtures were in a miscible liquid-disordered (L(d)) phase. Substitution of 7-ketocholesterol for cholesterol dramatically reduced the extent of DRM formation in DOPC/DPPC and DOPC/SM bilayers and ordered lipid phase separation in mixtures of a spin-labeled PC with DPPC and with SM. Compared to cholesterol, 7-ketocholesterol decreased the rate for the microsolubilization of dimyristoyl-PC multilamellar vesicles by apolipoprotein A-I. The membrane effects of 7-ketocholesterol were dependent on the phospholipid matrix. In L(d) phase phospholipids, a model for 7-ketocholesterol indicates that the proximity of the 7-keto and 3beta-OH groups puts both polar moieties at the lipid-water interface to tilt the sterol nucleus to the plane of the bilayer. 7-Ketocholesterol was less effective in forming ordered lipid domains, in decreasing the level of bilayer hydration, and in forming phase boundary bilayer defects. Compared to cholesterol, 7-ketocholesterol can differentially modulate membrane properties involved in protein-membrane association and function.






Massey JB,Pownall HJ




Has Abstract


2005-08-02 00:00:00












  • Crystal structure of substrate-free Pseudomonas putida cytochrome P-450.

    abstract::The crystal structure of Pseudomonas putida cytochrome P-450cam in the substrate-free form has been refined at 2.20-A resolution and compared to the substrate-bound form of the enzyme. In the absence of the substrate camphor, the P-450cam heme iron atom is hexacoordinate with the sulfur atom of Cys-357 providing one a...


    pub_type: 杂志文章


    authors: Poulos TL,Finzel BC,Howard AJ

    更新日期:1986-09-09 00:00:00

  • Phenylalanine hydroxylase: absolute configuration and source of oxygen of the 4a-hydroxytetrahydropterin species.

    abstract::The formation of tyrosine from phenylalanine catalyzed by rat liver phenylalanine hydroxylase is coupled to the generation of a 4a-hydroxy adduct from the requisite tetrahydropterin cofactor. As indicated by its circular dichroism (CD) spectrum, the optical activity of the adduct generated from racemic 6-methyltetrahy...


    pub_type: 杂志文章


    authors: Dix TA,Bollag GE,Domanico PL,Benkovic SJ

    更新日期:1985-06-04 00:00:00

  • Nucleotide specificity of stringent factor and the synthesis of analogs of guanosine 5'-diphosphate 3'-diphosphate and guanosine 5'-triphosphate 3'-diphosphate.

    abstract::The ribosome-dependent stringent factor reaction was found to be nonspecific with regard to the number of phosphate groups linked to the 5' position of guanosine nucleotides. Both GMP and guanosine 5'-tetraphosphate could accept a pyrophosphoryl group from ATP although at a much lower rate than GDP or GTP. Guanosine 5...


    pub_type: 杂志文章


    authors: Sy J

    更新日期:1975-03-11 00:00:00

  • Characterization of the phosphoserine of pepsinogen using 31P nuclear magnetic resonance: corroboration of X-ray crystallographic results.

    abstract::The endogenous phosphoserine residue in porcine pepsinogen has been titrated with use of phosphorus-31 nuclear magnetic resonance (31P NMR). It has an observed pKa2 of 6.7 and a narrow line width (congruent to 10 Hz). The phosphate can be readily removed by an acid phosphatase from potato; however, it is resistant to ...


    pub_type: 杂志文章


    authors: Williams SP,Bridger WA,James MN

    更新日期:1986-10-21 00:00:00

  • Distinct reactions catalyzed by bacterial and yeast trans-aconitate methyltransferases.

    abstract::The trans-aconitate methyltransferase from the bacterium Escherichia coli catalyzes the monomethyl esterification of trans-aconitate and related compounds. Using two-dimensional (1)H/(13)C nuclear magnetic resonance spectroscopy, we show that the methylation is specific to one of the three carboxyl groups and further ...


    pub_type: 杂志文章


    authors: Cai H,Strouse J,Dumlao D,Jung ME,Clarke S

    更新日期:2001-02-20 00:00:00

  • DNA ligase I from Saccharomyces cerevisiae: physical and biochemical characterization of the CDC9 gene product.

    abstract::Genetic studies have previously demonstrated that the Saccharomyces cerevisiae CDC9 gene product, which is functionally homologous to mammalian DNA ligase I, is required for DNA replication and is also involved in DNA repair and genetic recombination. In the present study we have purified the yeast enzyme. When measur...


    pub_type: 杂志文章


    authors: Tomkinson AE,Tappe NJ,Friedberg EC

    更新日期:1992-12-01 00:00:00

  • Cross-talk between protein kinase C-alpha (PKC-alpha) and -delta (PKC-delta): PKC-alpha elevates the PKC-delta protein level, altering its mRNA transcription and degradation.

    abstract::Studies utilizing the overexpression of individual isoforms indicated that both PKC-alpha and -delta promote a number of biological effects, including inhibition of DNA synthesis associated with rearrangements of the actin cytoskeleton in the murine B-cell lymphoma (Baf3), differentiation of the murine promyelocyte li...


    pub_type: 杂志文章


    authors: Romanova LY,Alexandrov IA,Nordan RP,Blagosklonny MV,Mushinski JF

    更新日期:1998-04-21 00:00:00

  • Phosphorylation of protein phosphatase 2Czeta by c-Jun NH2-terminal kinase at Ser92 attenuates its phosphatase activity.

    abstract::The protein phosphatase 2C (PP2C) family represents one of the four major protein Ser/Thr phosphatase activities in mammalian cells and contains at least 13 distinct gene products. Although PP2C family members regulate a variety of cellular functions, mechanisms of regulation of their activities are largely unknown. H...


    pub_type: 杂志文章


    authors: Awano K,Amano K,Nagaura Y,Kanno S,Echigo S,Tamura S,Kobayashi T

    更新日期:2008-07-08 00:00:00

  • Chloroperoxidase, a janus enzyme.

    abstract::Chloroperoxidase is a versatile fungal heme-thiolate protein that catalyzes a variety of one-electron and two-electron oxidations. We report here that the alkylation of an essential histidine residue showed no effect on the one-electron peroxidations but inhibited two-electron oxidations. The pH profiles of different ...


    pub_type: 杂志文章


    authors: Manoj KM,Hager LP

    更新日期:2008-03-04 00:00:00

  • Thermal, chemical, and enzymatic stability of the cyclotide kalata B1: the importance of the cyclic cystine knot.

    abstract::The cyclotides constitute a recently discovered family of plant-derived peptides that have the unusual features of a head-to-tail cyclized backbone and a cystine knot core. These features are thought to contribute to their exceptional stability, as qualitatively observed during experiments aimed at sequencing and char...


    pub_type: 杂志文章


    authors: Colgrave ML,Craik DJ

    更新日期:2004-05-25 00:00:00

  • Carbohydrate chains of human thyrotropin are differentially susceptible to endoglycosidase removal on combined and free polypeptide subunits.

    abstract::The accessibility of the asparagine-linked carbohydrate chains of human thyrotropin (hTSH) and free alpha and beta subunits was investigated by their susceptibility to endoglycosidases H and F as well as to peptide:N-glycosidase F. Iodinated hTSH or subunits were incubated with a commercial enzyme preparation containi...


    pub_type: 杂志文章


    authors: Ronin C,Papandreou MJ,Canonne C,Weintraub BD

    更新日期:1987-09-08 00:00:00

  • Relationship between Amphipathic β Structures in the β1 Domain of Apolipoprotein B and the Properties of the Secreted Lipoprotein Particles in McA-RH7777 Cells.

    abstract::Our previous studies demonstrated that the first 1000 amino acid residues (the βα1 domain) of human apolipoprotein (apo) B-100, termed apoB:1000, are required for the initiation of lipoprotein assembly and the formation of a monodisperse stable phospholipid (PL)-rich particle. The objectives of this study were (a) to ...


    pub_type: 杂志文章


    authors: Manchekar M,Kapil R,Sun Z,Segrest JP,Dashti N

    更新日期:2017-08-08 00:00:00

  • Mammalian glycinamide ribonucleotide transformylase: purification and some properties.

    abstract::Glycinamide ribonucleotide transformylase, the first of the two formyl group transferases of de novo purine biosynthesis requiring 10-formyltetrahydrofolate, has been purified 1500-fold, nearly to homogeneity, from the murine lymphoma cell line L5178Y. Purification of the enzyme was facilitated by the use of a gelatin...


    pub_type: 杂志文章


    authors: Caperelli CA

    更新日期:1985-03-12 00:00:00

  • Eukaryotic Catalase-Peroxidase: The Role of the Trp-Tyr-Met Adduct in Protein Stability, Substrate Accessibility, and Catalysis of Hydrogen Peroxide Dismutation.

    abstract::Recently, it was demonstrated that bifunctional catalase-peroxidases (KatGs) are found not only in archaea and bacteria but also in lower eukaryotes. Structural studies and preliminary biochemical data of the secreted KatG from the rice pathogen Magnaporthe grisea (MagKatG2) suggested both similar and novel features w...


    pub_type: 杂志文章


    authors: Gasselhuber B,Carpena X,Graf MM,Pirker KF,Nicolussi A,Sündermann A,Hofbauer S,Zamocky M,Furtmüller PG,Jakopitsch C,Oostenbrink C,Fita I,Obinger C

    更新日期:2015-09-08 00:00:00

  • Calorimetric study of the interaction of lysozyme with aqueous 1-propanol.

    abstract::The enthalpies of transfer of hen egg white lysozyme from water to aqueous solutions of 1-propanol were determined by isothermal flow calorimetry at 10, 17, 25, and 40 degrees C in 0.04 M, pH 2 glycine buffer. Alcohol concentrations up to 3.4 M were employed. Four regions in the dependence of the enthalpy of transfer ...


    pub_type: 杂志文章


    authors: Sturtevant JM,Velicelebi G

    更新日期:1981-05-26 00:00:00

  • 5'-Nucleotidase from rat heart.

    abstract::5'-Nucleotidase has been extracted from rat heart and purified to apparent homogeneity. The enzyme is a glycoprotein. Gel electrophoresis in the presence of sodium dodecyl sulfate indicates that the apparent molecular weight of the subunit is 74 000 at several different gel concentrations. Cross-linking of the native ...


    pub_type: 杂志文章


    authors: Naito Y,Lowenstein JM

    更新日期:1981-09-01 00:00:00

  • Structural and functional analysis of the HIV gp41 core containing an Ile573 to Thr substitution: implications for membrane fusion.

    abstract::The envelope glycoprotein of HIV-1 consists of the surface subunit gp120 and the transmembrane subunit gp41. Binding of gp120 to target cell receptors induces a conformational change in gp41, which then mediates the fusion of viral and cellular membranes. A buried isoleucine (Ile573) in a central trimeric coiled coil ...


    pub_type: 杂志文章


    authors: Liu J,Shu W,Fagan MB,Nunberg JH,Lu M

    更新日期:2001-03-06 00:00:00

  • Site-directed mutagenesis of tyrosine-71 to phenylalanine in Citrobacter freundii tyrosine phenol-lyase: evidence for dual roles of tyrosine-71 as a general acid catalyst in the reaction mechanism and in cofactor binding.

    abstract::Tyr71 is an invariant residue in all known sequences of tyrosine phenol-lyase (TPL). The substitution of Tyr71 in TPL by phenylalanine results in a mutant Y71F TPL with no detectable activity (greater than 3 x 10(5)-fold reduction) for beta-elimination of L-tyrosine. Y71F TPL can react with S-alkylcysteines, but these...


    pub_type: 杂志文章


    authors: Chen HY,Demidkina TV,Phillips RS

    更新日期:1995-09-26 00:00:00

  • Design, Synthesis, and Potency of Pyruvate Dehydrogenase Complex E1 Inhibitors against Cyanobacteria.

    abstract::Safe and effective algaecides are needed to control agriculturally and environmentally significant algal species. Four series (6, 10, 17, and 21) of 29 novel 4-aminopyrimidine derivatives were rationally designed and synthesized. A part of 10, 17, and 21 displayed potent inhibition of Escherichia coli pyruvate dehydro...


    pub_type: 杂志文章


    authors: Zhou Y,Feng J,He H,Hou L,Jiang W,Xie D,Feng L,Cai M,Peng H

    更新日期:2017-12-12 00:00:00

  • Structural analysis of calmodulin binding by nNOS inhibitory amphibian peptides.

    abstract::Calmodulin (CaM) is a ubiquitous protein in nature and plays a regulatory role in numerous biological processes, including the upregulation of nitric oxide (NO) synthesis in vivo. Several peptides that prevent NO production by interacting with CaM have been isolated in the cutaneous secretions of Australian amphibians...


    pub_type: 杂志文章


    authors: Calabrese AN,Bowie JH,Pukala TL

    更新日期:2015-01-20 00:00:00

  • Conversion of a cosubstrate to an inhibitor: phosphorylation mutants of nicotinic acid phosphoribosyltransferase.

    abstract::Nicotinic acid phosphoribosyltransferase (NAPRTase; EC forms nicotinic acid mononucleotide (NAMN) and PPi from 5-phosphoribosyl 1-pyrophosphate (PRPP) and nicotinic acid (NA). The Vmax NAMN synthesis activity of the Salmonella typhimurium enzyme is stimulated about 10-fold by ATP, which, when present, is hyd...


    pub_type: 杂志文章


    authors: Rajavel M,Lalo D,Gross JW,Grubmeyer C

    更新日期:1998-03-24 00:00:00

  • Effect of ADP on binding of skeletal S1 to F-actin.

    abstract::The proximity of skeletal myosin subfragment-1 (S1) to actin, and its orientation with respect to thin filaments of single muscle fibers, were compared in the presence and in the absence of ADP. The proximity was assessed by the efficiency of carbodiimide-induced cross-linking and the orientation by polarization of fl...


    pub_type: 杂志文章


    authors: Andreev OA,Ushakov DS,Borejdo J

    更新日期:1998-12-22 00:00:00

  • Determination of the rate-limiting steps and chemical mechanism of fructokinase by isotope exchange, isotope partitioning, and pH studies.

    abstract::Isotope exchange studies show that beef liver fructokinase has a random kinetic mechanism in which release of fructose from the enzyme is slower than that catalytic reaction. The stickiness of fructose in the presence of MgATP is confirmed by isotope partition studies, which show it to be released 0.53 times as fast a...


    pub_type: 杂志文章


    authors: Raushel FM,Cleland WW

    更新日期:1977-05-17 00:00:00

  • Aluminum exchange between citrate and human serum transferrin and interaction with transferrin receptor 1.

    abstract::The kinetics and thermodynamics of Al(III) exchange between aluminum citrate (AlL) and human serum transferrin were investigated in the 7.2-8.9 pH range. The C-site of human serum apotransferrin in interaction with bicarbonate removes Al(III) from Al citrate with an exchange equilibrium constant K1 = (2.0 +/- 0.6) x 1...


    pub_type: 杂志文章


    authors: Hémadi M,Miquel G,Kahn PH,El Hage Chahine JM

    更新日期:2003-03-18 00:00:00

  • Calcium and magnesium binding to human centrin 3 and interaction with target peptides.

    abstract::There are four isoforms of centrin in mammals, with variable sequence, tissue expression, and functional properties. We have recently characterized a number of structural, ion, and target binding properties of human centrin isoform HsCen2. This paper reports a similar characterization of HsCen3, overexpressed in Esche...


    pub_type: 杂志文章


    authors: Cox JA,Tirone F,Durussel I,Firanescu C,Blouquit Y,Duchambon P,Craescu CT

    更新日期:2005-01-25 00:00:00

  • Structural analysis of inositol monophosphatase complexes with substrates.

    abstract::The structures of ternary complexes of human inositol monophosphatase with inhibitory Gd3+ and either D- or L-myo-inositol 1-phosphate have been determined to 2.2-2.3 A resolution using X-ray crystallography. Substrate and metal are bound identically in each active site of the phosphatase dimer. The substrate is prese...


    pub_type: 杂志文章


    authors: Bone R,Frank L,Springer JP,Pollack SJ,Osborne SA,Atack JR,Knowles MR,McAllister G,Ragan CI,Broughton HB

    更新日期:1994-08-16 00:00:00

  • Nucleotide sequence of the gene for the gamma chain of human fibrinogen.

    abstract::A human genomic DNA library was screened for the gene coding for the gamma chain of fibrinogen by using a human cDNA for the gamma chain as a hybridization probe. The gene was identified in three overlapping recombinant lambda bacteriophage, and its sequence, including the immediate 5' and 3' flanking regions, was det...


    pub_type: 杂志文章


    authors: Rixon MW,Chung DW,Davie EW

    更新日期:1985-04-09 00:00:00

  • Generation of autonomous activity of Ca(2+)/calmodulin-dependent protein kinase kinase β by autophosphorylation.

    abstract::Ca(2+)/calmodulin-dependent protein kinase kinases (CaMKKs) phosphorylate and activate specific downstream protein kinases, including CaMKI, CaMKIV, and 5'-AMP-activated protein kinase, which mediates a variety of Ca(2+) signaling cascades. CaMKKs have been shown to undergo autophosphorylation, although their role in ...


    pub_type: 杂志文章


    authors: Tokumitsu H,Hatano N,Fujimoto T,Yurimoto S,Kobayashi R

    更新日期:2011-09-27 00:00:00

  • Isolation and structure of a cross-linked tripeptide from calf bone collagen.

    abstract::A cross-linked tripeptide has been isolated from alkaline hydrolysates of NaB3H4-reduced calf bone collagen. The peptide contains dihydroxylysinonorleucine, the most abundant cross-link in bone collagen, and it has a single N-terminal proline and a single C-terminal valine. These amino acids are in peptide linkage wit...


    pub_type: 杂志文章


    authors: Fujii K,Corcoran D,Tanzer ML

    更新日期:1975-10-07 00:00:00

  • Time-dependent inhibition of Bacillus stearothermophilus alanine racemase by (1-aminoethyl)phosphonate isomers by isomerization to noncovalent slowly dissociating enzyme-(1-aminoethyl)phosphonate complexes.

    abstract::An alanine racemase encoded by a gene from the thermophilic Gram-positive bacterium Bacillus stearothermophilus is overproduced to 0.3% of the soluble protein when carried on plasmid pICR4 in Escherichia coli [Inagaki, K., Tanizawa, K., Badet, B., Walsh, C. T., Tanaka, H., & Soda, K. (1986) Biochemistry (third paper o...


    pub_type: 杂志文章


    authors: Badet B,Inagaki K,Soda K,Walsh CT

    更新日期:1986-06-03 00:00:00