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PubMed1985

Promotion and inhibition of vesicle fusion by polylysine.

Polylysine induced rapid aggregation of large unilamellar vesicles composed of phosphatidylcholine-cardiolipin (1:1 molar ratio) but not their fusion. Application of the terbium-dipicolinic acid fusion assay showed that addition of polylysine at nanomolar concentrations enabled a significant lowering of the Ca2+ threshold concentration for vesicle fusion from 9 to 1 mM. Analysis of the kinetics of fusion with a mass-action kinetic model showed that polylysine enhanced significantly the rate of aggregation but affected only slightly the rate of fusion per se. Maximal enhancement of overall fusion rates occurred at a charge ratio (polylysine/cardiolipin) of about 0.5. At larger polylysine concentrations, e.g., at charge ratios greater than 3, polylysine inhibited vesicle fusion.

Calcium Chloride↗

PubMed2005

Esterified whey proteins can protect Lactococcus lactis against bacteriophage infection. Comparison with the effect of native basic proteins and L-polylysines.

Inhibitory action of basic esterified milk whey proteins [methylated (Met) or ethylated (Et) beta-lactoglobulin (BLG) and alpha-lactalbumin (ALA)], basic native proteins (chicken egg white lysozyme and calf thymus histone), and basic protein-like substances (L-polylysines) against the activity and replication of lactococcal bacteriophages (bIL66, bIL67, and bIL170) was tested. Chemical interactions of these proteins with phage DNA were determined as well as their protective effect on the growth of a laboratory plasmid-cured Lactococcus lactis subjected to an infection by the bacteriophages. All the proteins studied showed inhibitory activity against the three bacteriophages as tested by marked reduction of their lytic activities and decreasing the replication of studied phages. Histone and Met-BLG were more active toward bIL66 and bIL67, respectively, while both proteins were highly and equally active toward bIL170. Lysozyme showed lower antiviral activity. Antiviral activity of Et-BLG was a little bit lower than that observed in the case of the Met derivative. Esterified ALA also showed considerable but slightly lower antiviral activity as compared to other proteins. L-polylysines also showed an antiviral effect against the three bacteriophages studied, their influence being highly dependent on their molecular size. The best effective size of L-polylysines was in the range 15-70 kDa. Replication of bIL67 was inhibited by the presence of esterified ALA or BLG and native basic proteins. Complete inhibition of replication of bIL67 occurred when using polylysines with molecular masses in the ranges 4-15, 15-30, and 30-70 kDa, while protein-like substrates with lower molecular masses had only a slight effect. The presence of histone and Met-BLG at a concentration of 0.13 mg/mL in the incubation medium protected L. lactis against lysis when it was subjected to an infection by bIL67 (10(5) pfu/mL). The same action was achieved by l-polylysine (15-30 kDa) used at a concentration of 0.03 mg/mL in the incubation medium.

Bacteriophages↗

PubMed1994

Inhibition of leukaemia cell proliferation by folic acid-polylysine-mediated introduction of c-myb antisense oligodeoxynucleotides into HL-60 cells.

The inhibitory effect of c-myb antisense oligodeoxynucleotides (ODNs) conjugated to folic acid (FA) on HL-60 cell proliferation was examined. Folic acid was covalently linked to a polylysine chain and purified by gel chromatography. Sterile FA-polylysine was complexed with c-myb sense and antisense. Exposure of HL-60 cells to the FA-polylysine-c-myb antisense ODN complex resulted in a down-regulation of c-myb expression and a greater inhibition of proliferation than that obtained using free ODNs. Moreover, FA-polylysine conjugate alone or complexed to c-myb sense ODN was not toxic to cells. The antigenic properties and uptake of the vitamin were not affected by the polylysine chain. These data suggest that this strategy is potentially useful for the selective delivery of anti-oncogene-targeted ODNs into cancer cells.

Base Sequence↗

PubMed1975

Adhesion of cells to surfaces coated with polylysine. Applications to electron microscopy.

Cells of many kinds adhere firmly to glass or plastic surfaces which have been pretreated with polylysine. The attachment takes place as soon as the cells make contact with the surfaces, and the flattening of the cells against the surfaces is quite rapid. Cells which do not normally adhere to solid surfaces, such as sea urchin eggs, attach as well as cells which normally do so, such as amebas or mammalian cells in culture. The adhesion is interpreted simply as the interaction between the polyanionic cell surfaces and the polycationic layer of adsorbed polylysine. The attachment of cells to the polylysine-treated surfaces can be exploited for a variety of experimental manipulations. In the preparation of samples for scanning or transmission electron microscopy, the living material may first be attached to a polylysine-coated plate or grid, subjected to some experimental treatment (fertilization of an egg, for example), then transferred rapidly to fixative and further passed through processing for observation; each step involves only the transfer of the plate or grid from one container to the next. The cells are not detached. The adhesion of the cell may be so firm that the body of the cell may be sheared away, leaving attached a patch of cell surface, face up, for observation of its inner aspect. For example, one may observe secretory vesicles on the inner face of the surface (3) or may study the association of filaments with the inner surface (Fig. 1). Subcellular structures may attach to the polylysine-coated surfaces. So far, we have found this to be the case for nuclei isolated from sea urchin embryos and for the microtubules of flagella, which are well displayed after the membrane has been disrupted by Triton X-100 (Fig. 2).

Animals↗

PubMed1991

In vivo and in vitro evaluation of Gd-DTPA-polylysine as a macromolecular contrast agent for magnetic resonance imaging.

Polylysine covalently linked to moieties of gadopentetate (Gd-DTPA), for use as a macromolecular blood pool marker for contrast material-enhanced magnetic resonance imaging (MRI), was characterized by means of physicochemical measurements and pharmacokinetics in rats and rabbits and compared with Gd-DTPA. Gd-DTPA-polylysine was composed of a series of polymers of different molecular sizes that on average were labeled with 60 to 70 Gd-DTPA moieties (average molecular weight, 48,700 daltons [D]). For the macromolecular compound Gd-DTPA-polylysine, relaxivity was three times higher than that of Gd-DTPA. The LD50 value of 17 mmol/kg reflects a fairly high acute intravenous tolerance of the macromolecular compound in mice. Even though the volume of distribution of Gd-DTPA-polylysine in rabbits approached the extracellular fluid space (indicating that the macromolecular compound was also leaking slowly into the interstitial space), the half-life of distribution of the macromolecular compound in the extracellular fluid space was significantly prolonged, thus making the compound suitable as a blood pool marker for MRI. In rats the elimination of Gd-DTPA-polylysine occurred predominantly via the renal route. High-pressure liquid chromatography-size-exclusion chromatography of the fractionated urine samples revealed that the renal clearance must be the integral sum of the separate clearances of each molecular weight species. No biodegradation of the polypeptide was observed, and biodistribution studies revealed only minimal retention of Gd in the body of the rat.

Animals↗

PubMed1981

Vesicle surface charge and polylysine modification of ultraviolet absorption by the olefinic bonds in charged lipid.

The results of electrical conductivity and ultraviolet absorption studies on bilayer vesicles, composed of various mixtures of saturated dipalmitoylphosphatidylcholine (DPPC)and unsaturated bovine brain phoaphatidylserine (PS), in the presence and absence of polylysine indicate the following. (i) The two kinds of lipid maintain a strong transbilayer segregation over a wide range of proportions. The charged lipid (PS) preferentially locates in the inner, at PS proportions of 33% or less, and in the outer layer of the membranes when its proportion is increased to 50%. (ii) At PS proportions of 33% of less, where DPPC is the major component of the outer layer, the ability of polylysine to modify ultraviolet absorption by the olefinic bonds in the PS depends on the fluidity of the phosphatidylcholine. At higher PS proportions, where PS preferentially locates in the outer layer, modification of the ultraviolet absorption spectrum of the lipid by polylysine occurs only when the surface charge of the vesicles is diminished by the addition of bivalent metal ions. (iii) The polylysine-induced change in the ultraviolet absorption spectrum of the olefinic bonds in the vesicles was found to be very similar to that induced by dispersing unsaturated fatty acids in water rather than dissolving them in a nonpolar solvent. This suggests that polylysine modification of the vesicles spectrum may be the result of deep hydrophobic penetration by the polypeptide causing hydration and(or) parallel alignment of the dipole moments of the absorbing chromophores.

Chemical Phenomena↗

PubMedDate not supplied

Glioblastoma multiforme: MR imaging at 1.5 and 9.4 T after injection of polylysine-DTPA-Gd in rats.

Polylysine-DTPA-Gd, a new MR contrast agent, was injected into the aorta of rats 7 days after C6 glioblastoma was implanted in their brains; MR imaging was performed 3 days later. The imaging was done at two field strengths: (1) 1.5 T with a 3-mm slice thickness and in-plane resolutions of 600 microns and (2) 9.4 T with a 125- or 500-microns slice thickness and in-plane resolutions of 95 microns. In animals injected with polylysine-DTPA-Gd (1 microgram or more per rat), the T1-weighted images and mixed T1, T2 images of the C6 glioblastoma revealed a higher signal intensity at the marginal region between tumor and normal brain than that seen in surrounding normal brain. The central tumor region had a low signal intensity. The concentration of Gd in the C6 glioblastoma, after injection of 1 microgram polylysine-DTPA-Gd per rat, was calculated to be 0.14 mumol/l. The central tumor region also had a low signal intensity in animals that were not injected with the contrast agent, but the margin between tumor and normal brain was resolved poorly, if at all. The polylysine-DTPA-Gd revealed the microvasculature of the C6 glioblastoma in the 125-micron-thick slices obtained at 9.4 T. This is the first study to reveal the utility of the 9.4-T MR imager for examination of glioblastomas in situ and to demonstrate the utility of polylysine-DTPA-Gd as a contrast agent for the definition of the margin between glioblastoma and normal brain tissue.

Animals↗

PubMed1999

An in Situ Infrared Spectroscopic Investigation of Lysine Peptide and Polylysine Adsorption to TiO(2) from Aqueous Solutions.

An in situ infrared spectroscopic study of the adsorption of lysine peptides with n = 2-5 lysine units and polylysine (n = 169) on hydrous TiO(2) particle films is reported. Using attenuated total reflection infrared spectroscopy, it was found that dilysine adsorption to negatively charged TiO(2) from aqueous solutions pH 7.4 arose from electrostatic interactions. Increasing the number of lysine units to n = 3-5 resulted in infrared spectra which were changed, compared to solution species, upon adsorption to TiO(2). This indicated that the carboxylate group was involved in the peptide/TiO(2) interaction. Binding constants (K) for lysine peptide adsorption to TiO(2) were calculated by applying the Langmuir isotherm model. The K values obtained supported the onset of a stronger peptide-TiO(2) interaction going from dilysine to trilysine. Polylysine also adsorbed to TiO(2) from aqueous pH 7.4 solutions. Prolonged exposure of polylysine to TiO(2) (16.5 h) resulted in changed infrared spectra, implying that the secondary structure of polylysine was affected by adsorption. In contrast, the lysine peptides and polylysine did not adsorb to the hydrophobic ZnSe surface or positively charged chromium(III) oxide-hydroxide films, under the same experimental conditions. This indicates that electrostatic interactions of the lysine peptides with the adsorbent are of main importance to adsorption. Copyright 1999 Academic Press.

Journal Article↗

PubMed1997

Polylysine induces changes in membrane electrical properties of K562 cells.

The ionic environment of the cell membrane is of extreme importance in maintaining cell integrity and the numerous functions necessary for cell growth, differentiation, etc., as well as in cell-biomaterial interactions. In this study, the effects of polylysine (a basic poly-amino acid with a net positive charge which is often used to coat biomaterials surfaces) on the erythroleukemic K562 cell membrane were investigated. In particular, the effects of this polycation were evaluated using dielectric relaxation studies in the radiofrequency range with which it is possible to measure both active ionic transport across the cell membrane (membrane conductivity) and the static charge distribution present on the cell surface due to the structural components of the cell membrane (membrane permittivity). The conductivity of the cytosol can also be determined. The results demonstrate that while the conductivity of the cytosol is not significantly altered, both the conductivity and permittivity of the K562 cell membrane are varied by exposure of these cells to polylysine. These observations indicate that both active ionic transport and the type, quantity, or distribution of membrane components such as lipids, proteins, and polysaccharides may also be altered. Although the precise mechanisms by which these variations in K562 cells occur are unknown, it can be hypothesized that changes in the growth characteristics of these cells may be in part responsible. In particular, as demonstrated by light microscopic examination of K562 cells directly in the culture flasks, the cells in polylysine-coated flasks do not grow in suspension as do the controls, but rather show anchorage-dependent-like behavior. It is this important change from suspension to monolayer growth induced by polylysine that may be responsible for the changes in membrane electrical parameters.

Cell Division↗

PubMed2004

Hydration dependence of backbone and side chain polylysine dynamics: a 13C solid-state NMR and IR spectroscopy study.

The molecular dynamics of solid poly-L-lysine has been studied by the following natural abundance (13)C-NMR relaxation methods: measurements of the relaxation times T(1) at two resonance frequencies, off-resonance T(1rho) at two spin-lock frequencies, and proton-decoupled T(1rho). Experiments were performed at different temperatures and hydration levels (up to 17% H(2)O by weight). The natural abundance (13)C-CPMAS spectrum of polylysine provides spectral resolution of all types of backbone and side chain carbons and thus, dynamic parameters could be determined separately for each of them. At the same time, the conformational properties of polylysine were investigated by Fourier transform infrared spectroscopy. The data obtained from the different NMR experiments were simultaneously analyzed using the correlation function formalism and model-free approach. The results indicate that in dry polylysine both backbone and side chains take part in two low amplitude motions with correlation times of the order of 10(-4) s and 10(-9) s. Upon hydration, the dynamic parameters of the backbone remain almost constant except for the amplitude of the slower process that increases moderately. The side chain dynamics reveals a much stronger hydration response: the amplitudes of both slow and fast motions increase significantly and the correlation time of the slow motion shortens by about five orders of magnitude, and at hydration levels of more than 10% H(2)O fast and slow side chain motions are experimentally indistinguishable. These changes in the molecular dynamics cannot be ascribed to any hydration-dependent conformational transitions of polylysine because IR spectra reveal almost no hydration dependence in either backbone or side chain absorption domains. The physical nature of the fast and slow motions, their correlation time distributions, and hydration dependence of microdynamic parameters are discussed.

Magnetic Resonance Spectroscopy↗

PubMed1995

Polylysine cross-links axoplasmic neurofilaments into tight bundles.

We have used axoplasm from the squid giant axon to investigate the effects of anionic and cationic polypeptides on the mobility and organization of axonal neurofilaments (NFs). Intact cylinders of axoplasm were extruded from squid giant axons into an excess volume of artificial axoplasm solution. In a previous study on the mobility of NFs in extruded axoplasm, we showed that these polymers disperse freely and diffusively into the surrounding solution, thereby expanding the axoplasmic cross-sectional area [Brown and Lasek, 1993: Cell Motil. Cytoskeleton 26:313-324]. In the present study, we found that 83nm-long ("long-chain") polylysine, a synthetic multivalent cationic protein, inhibited the radial expansion of isolated axoplasm and condensed the axoplasm, thereby reducing the cross-sectional area. Equivalent concentrations of a 7nm-long ("short-chain") polylysine did not inhibit the expansion of axoplasm by long-chain polylysine was dependent on the polylysine concentration; condensation of axoplasm was observed at concentrations of 0.01 mg/ml (0.27 microM) or greater. Electron microscopy of the condensed axoplasm showed that the NFs were aligned side-by-side and in parallel in closely-packed bundles. Equivalent concentrations of 91 nm-long ("long-chain") polyglutamate, a synthetic multivalent anionic protein, partially inhibited the expansion of axoplasm but did not cause the NFs to bundle and did not cause the axoplasm to condense. These studies indicate that cationic proteins bind tightly to the highly charged anionic surfaces of NFs and can link them together into compact bundles in a charge-dependent and length-dependent manner. The tightly packed organization of these cross-linked NFs differs from the normal loose organization of NFs in healthy axons. However, tightly bundled NFs are sometimes found in certain neuropathologies, such as giant axonal neuropathy.

Animals↗

PubMed2005

Three-dimensional chemical structures by protein functionalized micron-sized beads bound to polylysine-coated silicone surfaces.

A novel method is described here that allows three-dimensional (3D) control of both chemistry and morphology by a series of wet chemical steps: the attachment of protein functionalized micron-sized beads onto a flat silicone surface that has been functionalized with a distinct chemical modification. Bovine serum albumin (BSA), laminin, or polylysine is covalently bound to 6.5-microm-diameter spherical beads. A chemical method is then used to bind these beads to a flat silicone surface that is subsequently functionalized with polylysine. This process leads to a nonspecific cell adhesive background on the flat surface (polylysine) with the option of differing chemistry on the third-dimension due to the protein BSA or laminin on the bead protruding from the surface. The beads do not detach during cyclic stretching in vitro. Neo-natal rat cardiac fibroblasts are cultured on the beaded surfaces and compared with fibroblasts cultured on nonbeaded, flat polylysine surfaces. Fibroblast plating density, integrin, and physical responses are examined as a function of varying the ligands on the beads.

Animals↗

PubMedDate not supplied

Acute occlusive ischemia of the rat intestine: early detection by MR imaging with polylysine-Gd-DTPA enhancement.

The purpose of this study was to assess the potential role of MR imaging with polylysine-Gd-DTPA enhancement in the early detection of acute occlusive intestinal ischemia in a rat model. After devascularization of the distal ileum in 12 rats, T2-weighted fast spin-echo MR images were acquired, followed by T1-weighted images before and after IV administration of 0.1 mmol/kg polylysine-Gd-DTPA. The signal intensity of the ischemic intestine did not differ significantly from that of the normal intestine before the administration of the contrast material. No mucosal or submucosal edema or hemorrhage was found in the ischemic intestine at histologic examination. After the administration of polylysine-Gd-DTPA, the ischemic intestine lacked enhancement and its signal intensity was significantly lower than that of the normal intestine. MR imaging with polylysine-Gd-DTPA enhancement can detect acute occlusive ischemia of the rat intestine at an early stage.

Acute Disease↗

PubMed1984

Colorimetric determination of microgram quantities of polylysine by trypan blue precipitation.

A simple and sensitive method for the determination of polylysine in solution is described. Polylysine is quantitatively precipitated with trypan blue. The absorbance of unbound dye in the supernatant is inversely proportional to the concentration of this polyamino acid. The precipitation is identical for all sizes of polylysine of molecular weight 13,000 or higher, and is prevented by the addition of either polyanions or serum. The measurable range of polylysine hydrobromide is between 1 and 10 micrograms/ml, which is about 10-fold lower than that by the published methyl orange precipitation method.

Azo Compounds↗

PubMed1986

Polylysine induces pH-dependent fusion of acidic phospholipid vesicles: a model for polycation-induced fusion.

Polylysine induced aggregation and fusion of negatively charged small unilamellar phosphatidylcholine vesicles containing at least 10% anionic lipid. Aggregation was followed by absorbance changes and fusion was assayed both by electron microscopy and by fluorescence energy transfer between lipid probes. A method for preparing asymmetric vesicles, where the fluorescent probes were present only in the inner monolayer of the vesicle membrane, was developed. These vesicles were used to distinguish the inner and outer monolayer when measuring lipid mixing between vesicles. Since polylysine induced lipid mixing of both monolayers equally, fusion of these vesicles did occur. The extent of fusion was dependent on the charge ratio between bound polylysine and phosphatidylserine (PS) in the outer monolayer and was optimal at a ratio of about 1:1. Excess polylysine inhibited fusion. At a given concentration of polypeptide, fusion increased as the pH was lowered toward 3 with an apparent pKa near 4. Since this value is close to the pKa of the PS-carboxyl groups and far from the pKa of the lysine epsilon-amino groups, the pH dependence observed for fusion resides in the lipids rather than in the peptide. Fusion was dependent on the available lysine and not the size or molarity of the polypeptide. The data indicate that there must be sufficient sites on the vesicles and sufficient polypeptide to achieve effective aggregation. For fusion to occur after aggregation, charges on the vesicles must be neutralized either by polypeptide-PS interaction or by protonation of the PS carboxyl groups. Optimal conditions for fusion occur when charge neutralization is possible without completely covering the vesicles with polypeptide. The results are consistent with the notion that the polypeptide is necessary for fusion because of requirements for crosslinking, but limits fusion by steric inhibition.

Cations, Divalent↗

PubMed1984

Dissipation of membrane potential of Escherichia coli cells induced by macromolecular polylysine.

Macromolecular polylysine caused a rapid and drastic decrease in the membrane potential of Escherichia coli cells, monitored with the uptake of the lipophilic cation, tetraphenylphosphonium cation (TPP+). Respiration of cells was not affected to a significant extent by polylysine. Polylysine treatment induced the efflux of K+ from cells, suggesting that an increase in permeability of cytoplasmic membrane may be responsible for the decrease in the membrane potential. The action of polylysine is discussed in comparison with that of colicin E1 which is known to dissipate the membrane potential of E. coli cells.

Cell Membrane Permeability↗

PubMed1991

Polylysine activates membrane-bound adenylyl cyclase from Xenopus laevis oocytes through the Gs transducing protein.

1. The activity of the adenylyl cyclase found in the membranes of Xenopus laevis can be affected by polylysine and other polycations. 2. The activity of the catalytic subunit measured with forskolin is inhibited by polylysine and polyarginine at concentrations above 10 microM and by spermine above 3 mM. 3. The adenylyl cyclase activity stimulated by GTP-gamma-S or F- through the stimulatory G protein (Gs) can be increased by polylysine, polyornithine and spermine but not by polyarginine. 4. Polylysine stimulation of Gs dependent activity is due to the increase in the apparent affinity for GTP-gamma-S and to a lowering of the requirement for Mg2+ concentration.

Adenylyl Cyclases↗

PubMed1997

The reduction of the positive charges of polylysine by partial gluconoylation increases the transfection efficiency of polylysine/DNA complexes.

A polylysine partially substituted with polyhydroxyalkanoyl residues and specially with gluconoyl residues was developed in order to increase the transfection efficiency by decreasing the strength of the electrostatic interactions between the DNA and the cationic polymer. Partially gluconoylated polylysine/DNA complexes were more easily dissociated in solution and their transfection efficiency in the presence of chloroquine, evaluated with HepG2 cells, a human hepatocarcinoma line, was higher when 43 +/- 4% of the epsilon-amino groups of polylysine were blocked with gluconoyl residues. Partially gluconoylated polylysine/plasmid complexes were efficient in transfecting different adherent as well as non-adherent cell lines. Partially gluconoylated polylysine formed highly soluble (above 100 micrograms/ml in DNA) complexes with DNA plasmids. In addition, partially gluconoylated polylysine bearing few lactosyl residues increased the transfection efficiency of HepG2 cells which express a galactose-specific membrane lectin.

Acylation↗