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B de Kruijff

Publications and source records attributed to B de Kruijff.

At least 199 records · Page 11Linked to original sources
PubMed1986

Gramicidin-induced hexagonal HII phase formation in negatively charged phospholipids and the effect of N- and C-terminal modification of gramicidin on its interaction with zwitterionic phospholipids.

The effect of gramicidin on macroscopic structure of the negatively charged membrane phospholipids cardiolipin, dioleoylphosphatidylglycerol and dioleoylphosphatidylserine in aqueous dispersions was investigated and compared with the effect of gramicidin on dioleoylphosphatidylcholine. It was shown by small-angle X-ray diffraction, 31P nuclear magnetic resonance and freeze-fracture electron microscopy that in all these lipid systems gramicidin is able to induce the formation of a hexagonal HII phase. 31P-NMR measurements indicated that the extent of HII phase formation in the various lipids ranged from about 40% to 60% upon gramicidin incorporation in a molar ratio of peptide to lipid of 1 : 10. Next, the following charged analogues of gramicidin were prepared: desformylgramicidin, N-succinylgramicidin and O-succinylgramicidin. The synthesis was verified with 13C-NMR and the effect of these analogues on lipid structure was investigated. It was shown that, as with gramicidin itself, the analogues induce HII phase formation in dioleoylphosphatidylcholine, lower and broaden the bilayer-to-HII phase transition in dielaidoylphosphatidylethanolamine and form lamellar structures upon codispersion with palmitoyllysophosphatidylcholine. Differential scanning calorimetry measurements indicated that, again like gramicidin, in phosphatidylethanolamine the energy content of the gel-to-liquid-crystalline phase transition is not affected by incorporation of the analogues, whereas in phosphatidylcholine a reduction of the transition enthalpy is found. These observations were explained in terms of a similar tendency to self-associate for gramicidin and its charged analogues. The results are discussed in the light of the various factors which have been suggested to be of importance for the modulation of lipid structure by gramicidin.

Calorimetry, Differential Scanning↗
PubMed1986

Studies on the lipid dependency and mechanism of the translocation of the mitochondrial precursor protein apocytochrome c across model membranes.

The lipid dependency of apocytochrome c binding to model membranes and of the translocation of the precursor protein across these membranes was studied by using large unilamellar, trypsin-containing vesicles. These vesicles were improved with respect to those used in a previous article (Rietveld, A., and de Kruijff, B. (1984) J. Biol. Chem. 259, 6704-6706), in the sense that a lower amount of trypsin was enclosed. In mixed egg phosphatidylcholine/bovine brain phosphatidylserine vesicles, both the Kd of apocytochrome c binding (about 20 microM) and the number of phosphatidylserine molecules interacting with the protein was found to be constant. When the phosphatidylserine fraction in the vesicles is more than 15-30% apocytochrome c addition results in the exposure of (a part of) the protein to the internal, trypsin-containing vesicle medium, which process we conceive as a translocation event. Also the interaction of apocytochrome c with vesicles composed of phosphatidylcholine and another acidic phospholipid in a 1:1 ratio, leads to the translocation of the protein across the model membrane. The affinity of this binding was found to be in the order cardiolipin greater than phosphatidylglycerol greater than phosphatidylinositol greater than phosphatidylserine. By varying the lipid composition of the vesicles, it could be demonstrated that the translocation requires a fluid bilayer. In addition, protein specificity was shown for the translocation process. Although apocytochrome c-lipid interaction causes vesicle aggregation, fusion by lipid mixing could not be detected. Due to the apocytochrome c-lipid interaction also, protein aggregates and oligomers have been formed. These results will be discussed in the light of a model for translocation of a precursor protein across a model membrane. The relevance for the mitochondrial system will also be discussed.

Animals↗
PubMed1986

Comparative 2H- and 31P-NMR study on the properties of palmitoyllysophosphatidylcholine in bilayers with gramicidin, cholesterol and dipalmitoylphosphatidylcholine.

The stoichiometric palmitoyllysophosphatidylcholine (lysoPC)/gramicidin (4:1, mol/mol) lamellar complex (Killian, J.A., De Kruijff, B., Van Echteld, C.J.A., Verkleij, A.J., Leunissen-Bijvelt, J. and De Gier, J. (1983) Biochim. Biophys. Acta 728, 141-144) is a useful model system to investigate the various aspects of lipid protein interactions. To study the effect of gramicidin on local order and motion of 1-palmitoyl-sn-glycero-3-phosphocholine (lysoPC) we employed 31P and 2H nuclear magnetic resonance (NMR) using selectively deuterated lysoPC's and we compared the results to those obtained for lysoPC in bilayers with cholesterol (1:1, mol/mol) and dipalmitoylphosphatidylcholine (DPPC) (1:4, mol/mol). 2H-NMR experiments on acyl chain deuterated lysoPC showed similar quadrupole splittings in the liquid crystalline state for the lysoPC/DPPC and the lysoPC/gramicidin samples. In the lysoPC/cholesterol sample an increase of the quadrupole splitting was found. T1 measurements showed that gramicidin decreases the lysoPC acyl chain motion, especially at the C12 position. In the lysoPC/cholesterol sample an increase of motion was observed as compared to lysoPC in fluid bilayers of DPPC. 31P-NMR and 2-H-NMR measurements of lysoPC, deuterated at the alpha- and beta-position of the choline moiety, indicated an increase in headgroup flexibility in all samples as compared to the parent compound DPPC. In addition, a change in headgroup conformation was observed. The alpha- and beta-segments in all samples exhibited concerted motion. It was found that also in the polar headgroup gramicidin induces a decrease of the rate of motion.

Cholesterol↗
PubMed1985

Thermodynamic, motional, and structural aspects of gramicidin-induced hexagonal HII phase formation in phosphatidylethanolamine.

The effect of gramicidin incorporation on the thermodynamic properties of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) dispersions was investigated by differential scanning calorimetry. The results show that incorporation of gramicidin in PC systems results in a decrease of the energy content of the gel to liquid-crystalline phase transition. When incorporated in PE systems, however, the peptide does not affect the properties of the gel to liquid-crystalline phase transition with the exception that at high gramicidin concentrations the onset of the melting process is shifted to a slightly lower temperature. We therefore assume that in the lamellar gel state of PE aggregation of the peptide occurs. To get more insight into the nature of the gramicidin-PE interaction, we studied the motional and structural details of HII phase formation in gramicidin/PE systems with the use of 31P and 13C nuclear magnetic resonance (NMR) and small-angle X-ray diffraction. In agreement with earlier results [Van Echteld, C. J. A., Van Stigt, R., de Kruijff, B., Leunissen-Bijvelt, J., Verkleij, A. J., & De Gier, J. (1981) Biochim. Biophys. Acta 648, 287-291] it was shown that gramicidin incorporation lowers and broadens the bilayer to hexagonal HII phase transition in PE systems. 31P NMR chemical shift anisotropy (CSA) measurements indicated that a phase separation occurs between a gramicidin-poor lamellar phase and a gramicidin-rich HII phase. From combined CSA and spin-lattice relaxation time (T1) measurements it was suggested that in the HII phase gramicidin decreases the molecular order and increases the rate of motion of the phosphate moiety of PE. In addition, 13C NMR line width measurements indicated that the acyl chains are more disordered in the HII phase than in the lamellar phase and that a similar disorder occurs in the HII phase of the pure PE as in the gramicidin-rich HII phase. This interpretation was supported by the X-ray diffraction data, which show similar first-order repeat distances in both types of HII phase. From saturation-transfer NMR experiments in PE and gramicidin-PE mixtures it was shown that no exchange occurs between the lamellar and the HII phases in the time scale of 1-2 s, suggesting a macroscopic phase separation. Finally, we discussed the gramicidin-lipid interaction and in particular the HII phase formation by gramicidin in PE and in PC systems. It is proposed that aggregation of the peptide plays a crucial role in HII phase formation.

Calorimetry, Differential Scanning↗
PubMed1985

Importance of hydration for gramicidin-induced hexagonal HII phase formation in dioleoylphosphatidylcholine model membranes.

The macroscopic organization, lipid head group conformation, and structural and dynamic properties of 2H2O were investigated in dioleoylphosphatidylcholine (DOPC) model systems of varying gramicidin and 2H2O (or H2O) content by means of small-angle X-ray diffraction and 31P and 2H NMR. At low stages of hydration, N less than 6 (N = 2H2O/DOPC molar ratio), a single lamellar phase is observed in which the gramicidin molecules become preferentially hydrated upon increasing N. For 6 less than N less than 12 phase separation occurs between a gramicidin-poor and a gramicidin-rich lamellar phase. This latter phase is characterized by a smaller repeat distance and decreased DOPC head group order. For N greater than 12, the gramicidin-rich lamellar phase converts to a hexagonal HII phase. Thus, hydration of gramicidin is a prerequisite for HII phase formation in the DOPC/gramicidin system. The HII phase is very rich in gramicidin and 2H2O (gramicidin:DOPC:H2O = 1:1.1:0.9 w/w/w). A model is proposed in which self-assembly of hydrated gramicidin molecules into domains of a specific structure plays a determinant role in the formation of the HII phase by gramicidin.

Gramicidin↗
PubMed1985

Penetration of a cardiotoxin into cardiolipin model membranes and its implications on lipid organization.

The interaction of cardiotoxin II of Naja mossambica mossambica with cardiolipin model membranes was investigated by binding, fluorescence, resonance energy transfer, fluorescence quenching, 31P NMR, freeze-fracture, and small-angle X-ray experiments. An initially electrostatic binding appeared to be accompanied by a deep penetration, most likely into the acyl chain region of the phospholipids, indicating a hydrophobic contribution to the strong interaction (KD congruent to 5 X 10(-8) M). This binding results in a fusion of unilamellar vesicles as indicated by a fluorescence-based fusion assay, freeze-fracture, and X-ray diffraction. In these fused structures freeze-fracture electron microscopy reveals the appearance of particles, which is accompanied by the induction of an isotropic component in 31P NMR. The well-defined particles are interpreted as inverted micelles, and the localization of the cardiotoxin molecule in these structures is discussed.

Animals↗
PubMed1985

Molecular aspects of the bilayer stabilization induced by poly(L-lysines) of varying size in cardiolipin liposomes.

The interaction between poly(L-lysines) of varying size with cardiolipin was investigated via binding assays, X-ray diffraction, freeze-fracture electron microscopy, and 31P- and 13C-NMR. Binding of polylysines to the lipid only occurred when three or more lysine residues were present per molecule. The strength of the binding was highly dependent on the polymerization degree, suggesting a cooperative interaction of the lysines within the polymer. Upon binding, a structural reorganization of the lipids takes place, resulting in a closely packed multilamellar system in which the polylysines are sandwiched in between subsequent bilayers. Acyl chain motion is reduced in these liquid-crystalline peptide-lipid complexes. From competition experiments with Ca2+ it could be concluded that when the affinity of the polylysine for cardiolipin was much larger than that of Ca2+, a lamellar polylysine-lipid complex was formed, irrespective of whether an excess of Ca2+ was added prior to or after the polypeptide. When the affinity of the polylysine for cardiolipin was less or of the same order as that of Ca2+, the lipid was organized in the hexagonal HII phase in the presence of Ca2+. These results are discussed in the light of the peptide specificity of bilayer (de)stabilization in cardiolipin model membranes.

Calcium↗
PubMed1985

Influence of glycophorin incorporation on Ca2+-induced fusion of phosphatidylserine vesicles.

The effect of incorporation of glycophorin, the major integral sialoglycoprotein of the erythrocyte membrane, into bovine brain phosphatidylserine (PS) vesicles on the Ca2+-induced fusion of these vesicles has been investigated. Fusion was monitored by the terbium-dipicolinic acid fluorescence assay for the mixing of aqueous contents of the vesicles and by a resonance energy transfer assay that follows the intermixing of membrane lipids. The Ca2+-induced fusion of PS vesicles is completely prevented by incorporation of glycophorin (molar ratio of PS/glycophorin = 400-500:1) for Ca2+ concentrations up to 50 mM. The ability to fuse is partially restored after treating the glycophorin-containing vesicles with neuraminidase, which removes the negatively charged sialic acid residues of glycophorin. Fusion is further facilitated by trypsin treatment, removing the entire extravesicular glycosylated head group of glycophorin. However, Ca2+-induced fusion of enzyme-treated glycophorin-PS vesicles proceeds at a slower rate and to a smaller extent than fusion of protein-free PS vesicles. The influence of the aggregation state of the glycophorin molecules on fusion has been investigated in experiments using wheat germ agglutinin (WGA). Addition of WGA to the glycophorin-PS vesicles does not induce fusion. However, upon subsequent addition of Ca2+, distinct fusion occurs concomitantly with release of vesicle contents. The inhibition of Ca2+-induced fusion of PS vesicles by incorporation of glycophorin is explained by a combination of steric hindrance and electrostatic repulsion between the vesicles by the glycosylated head group of glycophorin and a direct bilayer stabilization by the intramembranous hydrophobic part of the glycophorin molecule.

Animals↗
PubMed1985

Effects of adriamycin on lipid polymorphism in cardiolipin-containing model and mitochondrial membranes.

The effects of the anti-tumor drug adriamycin on lipid polymorphism in cardiolipin-containing model membranes and in isolated inner mitochondrial membranes has been examined by 31P-NMR. Adriamycin binding does not affect the macroscopic structure or local order in the phosphate region of cardiolipin liposomes. In cardiolipin liposomes and in cardiolipin-phosphatidylcholine (1:1) liposomes, the drug inhibits the ability of Ca2+ to induce the hexagonal HII phase. Adriamycin interaction with both dioleoylphosphatidylethanolamine-cardiolipin (2:1) and dioleoylphosphatidylethanolamine-phosphatidylserine (1:1) liposomes results in structural phase separation into a liquid-crystalline hexagonal HII phase for the phosphatidylethanolamine and a liquid-crystalline lamellar phase for the negatively charged phospholipid. Combined high-resolution 31P-NMR, electron microscopy and light scattering studies reveal the prominent fusion capacity of adriamycin towards cardiolipin-phosphatidylcholine small unilamellar vesicles. Addition of Ca2+ to total rat liver inner mitochondrial membrane lipids, dispersed in excess buffer, results in hexagonal HII formation for part of the phospholipids. By contrast, the original bilayer structure is completely conserved when the above experiment is performed in the presence of adriamycin. 31P-NMR spectra of isolated inner mitochondrial membranes are indicative of a bilayer organization for the majority of the phospholipids. Approximately 15% of the signal intensity originates from phospholipids which experience isotropic motion. Adriamycin addition almost completely eliminates the latter spectral component. In the absence of adriamycin, Ca2+ addition greatly increases the percentage of the phospholipids giving rise to an isotropic signal possibly indicating the formation of non-lamellar lipid structures. Adriamycin which specifically binds to cardiolipin (K. Nicolay et al. (1984) Biochim. Biophys. Acta 778, 359-371) completely blocks the Ca2+-induced structural reorganization of the lipids in this membrane.

Calcium↗
PubMed1985

Investigations on the insertion of the mitochondrial precursor protein apocytochrome c into model membranes.

Different aspects of the interaction of apocytochrome c and model membranes composed of negatively charged lipids, were studied in order to get insight into the nature of this interaction. The effect of the protein on the lipid packing properties are revealed by DSC, ESR and monolayer techniques. These experiments clearly demonstrate that upon electrostatic interaction with the negatively charged phospholipids, apocytochrome c is able to penetrate into the hydrophobic region of the model membrane. In the case of 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol, this results in a perturbation of 160 lipid molecules per apocytochrome c molecule. Most likely, apocytochrome c disrupts the formation of the gel phase and restricts the lipid chain motion above the gel to liquid-crystalline phase transition. Tryptophan fluorescence measurements confirm that at least a part of the protein penetrates into the bilayer, and suggest that after this penetration, the tryptophan (residue no. 59) is located in the glycerol backbone region of the phospholipids. Although the secondary structure of apocytochrome c is predicted to contain about 35% of alpha-helical structure, the CD pattern of an aqueous solution of the protein is featureless. However, negatively charged lipids are able to express this alpha-helical potency in the apocytochrome c, which might be important for the insertion of the protein into lipid membranes.

Animals↗
PubMed1985

Essential adaptation of the calcium influx assay into liposomes with entrapped arsenazo III for studies on the possible calcium translocating properties of acidic phospholipids.

An adapted version of the Ca2+-influx assay of Weissmann et al. (Weissmann, G., Anderson, P., Serhan, C., Samuelson, E. and Goodman, E. (1980) Proc. Natl. Acad. Sci. USA 77, 1506-1510) is presented for studies on the possible ionophoretic properties of acidic phospholipids. This method is based on the use of the metallochromic dye arsenazo III enclosed in liposomal vesicles, to indicate the Ca2+ influx. An essential control is introduced to discriminate between Ca2+-arsenazo III complex formation inside the vesicles, as a consequence of Ca2+ influx, and outside the vesicles, as a consequence of arsenazo III leakage from the vesicles. Furthermore, some minor improvements are added, like the use of large unilamellar vesicles instead of multilamellar vesicles, and the use of dual wavelength spectrophotometry. Using this method, it was found that dioleoylphosphatidylcholine vesicles, containing 20 mol% dioleoylphosphatidylglycerol, were impermeable to Ca2+. In this system a selective Ca2+ permeability could be induced by the addition of the fungal Ca2+ ionophore A23187. In contrast, dioleoylphosphatidylcholine vesicles, containing 20 mol% dioleoylphosphatidic acid, incubated in the presence of Ca2+ were permeable to both Ca2+ and arsenazo III.

Arsenazo III↗
PubMed1985

The influence of dolichol, dolichol esters, and dolichyl phosphate on phospholipid polymorphism and fluidity in model membranes.

The effect of dolichols, polyprenols, dolichol esterified with fatty acids, and dolichyl phosphate on the structure and fluidity of model membranes was studied using 31P NMR, small-angle x-ray scattering, differential scanning calorimetry, and freeze-fracture electron microscopy. These studies suggest that dolichol and dolichol derivatives destabilize unsaturated phosphatidylethanolamine containing bilayer structures and promote hexagonal II phase formation; high concentrations of dolichol induce lipid structures characterized by "isotropic" 31P NMR and particulate fracture faces; dolichol, contrary to cholesterol, has no effect on the thermotropic behavior of membranes consisting of phosphatidylcholine, while dolichyl-P incorporation abolishes the transition from the gel to liquid crystalline phase in 1,2-dimyristoyl-sn-glycero-3-phosphocholine; both dolichol and dolichyl-P increase the fatty acid fluidity in phosphatidylethanolamine mixtures; the effect of dolichol on bilayer structure and fluidity is more pronounced with increasing number of isoprene residues; dolichol esters are only soluble to a limited extent in the bilayer and segregates into domains at low concentrations; the results are consistent with a localization of dolichyl-P in which the phosphate group is oriented to the water interphase. The induction of hexagonal II phase by dolichyl-P may elicit the transmembrane movement of glycosylated lipid intermediate.

Calorimetry, Differential Scanning↗
PubMed1985

The influence of lipid composition and lectin-glycophorin interaction on the rotational diffusion of glycophorin in vesicles, as measured by time-resolved phosphorescence depolarization.

The rotational mobility of glycophorin in various lipid vesicles was studied, using time-resolved measurements of the depolarization of laser flash excited phosphorescence of glycophorin labelled with the triplet probe erythrosin. With the exception of dimyristoylphosphatidylcholine at the phase transition no phosphorescence depolarization decays were observed in the 1-300 microseconds time interval following the laser flash. Instead, a constant anisotropy level was observed, with two distinct values depending on the experimental system. In liquid-crystalline bilayers of dioleoylphosphatidylcholine, bovine brain phosphatidylserine and dimyristolyphosphatidylcholine, the anisotropy was 0.01. This was increased to 0.03 upon addition of wheat germ agglutinin which aggregates glycophorin. In the case of gel state dimyristoylphosphatidylcholine and liquid-crystalline dioleoylphosphatidylethanolamine the anisotropy also amounted to 0.03. Experiments with glycerol to vary the viscosity of the medium, and theoretical considerations, exclude the possibility that these different anisotropy levels are related to differences in motional properties of the entire protein/lipid vesicles. These results strongly suggest that the anisotropy level of 0.03 corresponds to slowly rotating glycophorin (rotational relaxation time greater than 0.3 ms) while the anisotropy level of 0.01 corresponds to fast rotating glycophorin (rotational correlation time less than 1 microseconds). The difference in glycophorin mobility is discussed in terms of aggregation state of the protein, lipid composition of the vesicle bilayer and membrane viscosity. The observed differences in rotational mobility of glycophorin in glycophorin/dioleoylphosphatidylcholine vesicles, glycophorin/bovine heart phosphatidylserine vesicles as compared to glycophorin/dioleoylphosphatidylethanolamine vesicles are not in quantitative agreement with the relative size of the intramembrane particles in these systems as revealed by freeze-fracture electron microscopy.

Animals↗
PubMed1985

Isolation and purification of cardiolipin from beef heart.

A simple and efficient procedure is described for the preparation of cardiolipin sodium salt from beef heart. A crude phospholipid fraction is isolated by chloroform-methanol extraction of the homogenized tissue, followed by acetone precipitation and reprecipitation in 4% aqueous CaCl2-methanol. Cardiolipin is separated from the calcium salts of the acidic phospholipids by partition column chromatography on silica gel (Polygosil 60-63100) using 2-propanol-cyclohexane-water 50:43:7 (v/v/v) as eluent. Further purification of the cardiolipin is achieved by high performance liquid chromatography of the calcium salt on silica gel (Lichrosorb Si 60-5) with a neutral eluent (2-propanol-cyclohexane-water 45:50:5 (v/v/v], followed by quantitative conversion to the sodium salt. The yield of this procedure is 1.5-2.1 g of pure 99% sodium salt of cardiolipin per kg of moist ventricular tissue.

Animals↗
PubMed1984

Influence of phospholipid peroxidation on the phase behavior of phosphatidylcholine and phosphatidylethanolamine in aqueous dispersions.

The influence of oxygen-induced phospholipid peroxidation on the phase behavior of aqueous dispersions of both egg phosphatidylcholine (egg-PC) and egg phosphatidylethanolamine (egg-PE) has been investigated. Phospholipid peroxidation was followed via malondialdehyde formation and analyses of acyl chain compositions. 13C nuclear magnetic resonance spectroscopy (NMR) and the amino-indicating probe trinitrobenzenesulfonic acid were used to study the effect of peroxidation on the chemical structure of hydrated egg-PE. The macroscopic organization of the phospholipids was monitored by 31P NMR and small-angle X-ray diffraction. Differential scanning calorimetry was employed to study the influence of peroxidation on the thermotropic behavior of egg-PE. The results show that egg-PE is more sensitive to the effects of peroxidation than egg-PC. In the latter, no changes in the macromolecular organization were observed. However, peroxidation strongly influenced the polymorphic phase behavior of PE. Initial peroxidation stabilized hydrated egg-PE in a lamellar system up to 70 degrees C, presumably by modification of the head group. Such modifications were confirmed by 13C NMR experiments, which indicated the formation of Schiff bases between PE head groups and aldehydes. Furthermore, quantitative analyses of trinitrobenzenesulfonic acid reactable egg-PE and the corresponding fatty acid compositions revealed the presence of cross-links between the ethanolamine head groups, likely involving the bifunctional malondialdehyde. Prolonged peroxidation of egg-PE resulted in a loss of order in the system, possibly by the formation of intermediate nonbilayer structures.

Animals↗