Biomedical subjects

S Nir

Publications and source records attributed to S Nir.

At least 19 recordsLinked to original sources

PubMed2003

Kinetics of influenza virus fusion with the endosomal and plasma membranes of cultured cells. Effect of temperature.

We performed a detailed kinetic analysis of influenza virus fusion with the endosomal and plasma membranes of Madin Darby canine kidney (MDCK) cells and provided a comparison of the kinetic parameters obtained for both cases at 20 degrees C and 37 degrees C. Using our mass action kinetic model, we determined that the fusion rate constant, f, for influenza virus with the endosomal membrane was 0.02 s(-1) at 37 degrees C and 0.0035 s(-1) at 20 degrees C. The analysis of the fusion kinetics of influenza virus with the plasma membrane yielded that the fusion rate constants were close to those deduced with the endosomal membrane. The systematic kinetic analysis performed in this study provides for the first time a biophysical support for studies on influenza virus-cell fusion where the acidic endosomal internal environment is simulated artificially by lowering the pH of the medium.

Animals↗

PubMed2001

Kinetic analysis of the initial steps involved in lipoplex--cell interactions: effect of various factors that influence transfection activity.

We investigated the mode of interaction of lipoplexes (DOTAP:DOPE/DNA) with HeLa cells, focusing on the analysis of the initial steps involved in the process of gene delivery. We evaluated the effect of different factors, namely the stoichiometry of cationic lipids and DNA, the presence of serum in the cell culture medium, and the incorporation of the ligand transferrin into the lipoplexes, on the extent of binding, association and fusion (lipid mixing) of the lipoplexes with the cells. Parallel experiments were performed upon cell treatment with inhibitors of endocytosis. Our results indicate that a decrease of the net charge of the complexes (upon addition of DNA) generally leads to a decrease in the extent of binding, cell association and fusion, except for the neutral complexes. Association of transferrin to the lipoplexes resulted in a significant enhancement of the interaction processes referred to above, which correlates well with the promotion of transfection observed under the same conditions. Besides triggering internalization of the complexes, transferrin was also shown to mediate fusion with the endosomal membrane. The extent of fusion of this type of complexes was reduced upon their incubation with cells in the presence of serum, suggesting that serum components limit the transferrin fusogenic properties. Results were analyzed by using a theoretical model which allowed to estimate the kinetic parameters involved in lipoplex--cell interactions. The deduced fusion and endocytosis rate constants are discussed and compared with those obtained for other biological systems. From the kinetic studies we found a twofold enhancement of the fusion rate constant (f) for the ternary lipoplexes. We also concluded that HeLa cells yield a relatively low rate of endocytosis. Overall, our results estimate the relative contribution of fusion of lipoplexes with the plasma membrane, endocytosis and fusion with the endosomal membrane to their interactions with cells, this information being of crucial importance for the development of gene therapy strategies.

Blood↗

PubMed2001

A model for proto-tRNA loading.

A kinetic model for loading of proto-tRNA is presented. The kinetic parameters were first estimated from the results of Francklyn & Schimmel (1989;Nature337, 478--481), who studied the aminoacylation of both tRNA and its minihelix. Then these parameters were reduced several-fold, as is more appropriate for the prebiotic world. The simulations revealed a very slow time course of the loading reaction. We also consider a possibility for the proto-tRNA loading without a catalyst and discuss the feasibility of such processes. Analytical approximations are presented for the kinetics of proto-tRNA loading with and without enzyme. An estimate is given for the time required for the development of template- and sequence-directed systems.

Animals↗

PubMed2001

Simulation of non-enzymatic template-directed synthesis of oligonucleotides and peptides.

A simulation model is proposed for the template- and sequence-directed (TSD) condensation of two trideoxyribonucleotide 3'-phosphate molecules into a hexameric template with palindromic sequence studied experimentally by von Kiedrowski (1986;Angew. Int. Ed. Engl.25, 932--935). The model simulates reasonably well the kinetics of synthesis of both the template, and the pyrophosphate product which is not directly involved in the autocatalytic reaction. It offers quantitative approximation of the different rate constants of the processes involved in the reaction. The model simulates and gives predictions for the influence of factors such as the initial concentrations of the trimers and the template, and gives predictions for the effect of temperature on the dynamics of the autocatalytic reaction. The model also simulates well the production rate of a different self-replicating system (coiled coil peptide) used in the experiments of Lee et al. (1997;Nature390, 591--594). Comparing the different rate constants, it seems that chain elongation occurs at higher rates in the peptide system (at 23 degrees C) than in the nucleotide one (at 0 degrees C), but that the relative contribution of template-directed synthesis is significantly larger with the nucleotides.

Animals↗

PubMed2001

The emergence of life on Earth.

Combined top-down and bottom-up research strategies and the principle of biological continuity were employed in an attempt to reconstruct a comprehensive origin of life theory, which is an extension of the coevolution theory (Lahav and Nir, Origins of Life Evol. Biosphere (1997) 27, 377-395). The resulting theory of emergence of templated-information and functionality (ETIF) addresses the emergence of living entities from inanimate matter, and that of the central mechanisms of their further evolution. It proposes the emergence of short organic catalysts (peptides and proto-ribozymes) and feedback-loop systems, plus their template-and-sequence-directed (TSD) reactions, encompassing catalyzed replication and translation of populations of molecules organized as chemical-informational feedback loop entities, in a fluctuating (wetting-drying) environment, functioning as simplified extant molecular-biological systems. The feedback loops with their TSD systems are chemically and functionally continuous with extant living organisms and their emergence in an inanimate environment may be defined as the beginning of life. The ETIF theory considers the emergence of bio-homochirality, a primordial genetic code, information and the incorporation of primordial metabolic cycles and compartmentation into the emerging living entities. This theory helps to establish a novel measure of biological information, which focuses on its physical effects rather than on the structure of the message, and makes it possible to estimate the time needed for the transition from the inanimate state to the closure of the first feedback-loop systems. Moreover, it forms the basis for novel laboratory experiments and computer modeling, encompassing catalytic activity of short peptides and proto-RNAs and the emergence of bio-homochirality and feedback-loop systems.

Biological Evolution↗

PubMed2001

Organo-clay formulation of acetochlor for reduced movement in soil.

This study aimed to design ecologically acceptable formulations of acetochlor by adsorbing it on montmorillonite exchanged by a small organic cation, phenyltrimethylammonium (PTMA). Adsorption of acetochlor on the clay mineral exchanged with different organic cations and its release from these complexes were determined by GC and modeled by Langmuir equation. Interactions between acetochlor molecules and the exchanged organic cation on the clay surface were studied by Fourier transform infrared spectroscopy. Leaching of acetochlor in soil was determined by a bioassay using a column technique and Setaria viridis as a test plant. The adsorbed amounts of acetochlor on montmorillonite exchanged by PTMA at a loading of 0.5 mmol/g of clay were higher than at a loading up to the cation-exchange capacity, i.e., 0.8 mmol/g, and were higher than obtained by using a clay mineral exchanged by other organic cations. Preloading montmorillonite by PTMA at 0.5 mmol/g yielded maximal shifts of the infrared peaks of the herbicide. The above formulation of acetochlor yielded slow release in water and showed improved weed control in field and greenhouse experiments in comparison with the commercial formulation. The PTMA-clay formulation of acetochlor maintained herbicidal activity in the topsoil and yielded the most significant reduction in herbicide leaching and persistence under field conditions. The application of this formulation can minimize the risk to groundwater and can reduce the applied rates.

Adsorption↗

PubMed2000

The pre-transmembrane region of the human immunodeficiency virus type-1 glycoprotein: a novel fusogenic sequence.

We have investigated membrane interactions and perturbations induced by NH(2)-DKWASLWNWFNITNWLWYIK-COOH (HIV(c)), representing the membrane interface-partitioning region that precedes the transmembrane anchor of the human immunodeficiency virus type-1 gp41 fusion protein. The HIV(c) peptide bound with high affinity to electrically neutral vesicles composed of dioleoylphosphatidylcholine, dioleoylphosphatidylethanolamine and cholesterol (molar ratio, 1:1:1), and induced vesicle leakage and lipid mixing. Infrared spectra suggest that these effects were promoted by membrane-associated peptides adopting an alpha-helical conformation. A sequence representing a defective gp41 phenotype unable to mediate both cell-cell fusion and virus entry, was equally unable to induce vesicle fusion, and adopted a non-helical conformation in the membrane. We conclude that membrane perturbation and adoption of the alpha-helical conformation by this gp41 region might be functionally meaningful.

Amino Acid Sequence↗

PubMed2000

Interaction of TAFII105 with selected p65/RelA dimers is associated with activation of subset of NF-kappa B genes.

TAF(II)105, a substoichiometric coactivator subunit of TFIID, is important for activation of anti-apoptotic genes by NF-kappaB in response to the cytokine tumor necrosis factor (TNF)-alpha. In the present study we have analyzed the mechanism of TAF(II)105 function with respect to its regulation of p65/RelA, a component of NF-kappaB. We found two independent p65/RelA-binding domains within the N terminus of TAF(II)105. One of these domains appears to be crucial for TAF(II)105-mediated anti-apoptotic gene activation in response to TNF-alpha. Analysis of the interaction between TAF(II)105 and different NF-kappaB complexes has revealed substantial differences in the affinity of TAF(II)105 toward different p65/RelA-containing dimers. We have identified the TNF-alpha induced anti-apoptotic A20 gene as a target gene of TAF(II)105. A20 has a differential protective effect on cell death induced by TNF-alpha in the presence of either the dominant negative mutant of TAF(II)105 (TAF(II)105DeltaC) or the superdominant IkappaBalpha. The results suggest that the inhibitory effect of TAF(II)105DeltaC on NF-kappaB-dependent genes is restricted to a subset of anti-apoptotic genes while the effect of IkappaBalpha is more general. Thus, an interaction between NF-kappaB and a specific coactivator is important for specifying target gene activation.

Animals↗

PubMed2000

Adsorption and Interactions of Methyl Green with Montmorillonite and Sepiolite.

The divalent organic cation, methyl green (MG), undergoes a slow transformation (6 h) to a monovalent cation, carbinol (MGOH(+)) upon dilution of its solution (10 mM), or in a buffer at neutral pH. Adsorption isotherms of MG on montmorillonite were determined by two procedures, both of which yield a final pH of suspensions between 7 to 7.4. When the amounts of MG in suspension were lower than the cation-exchange capacity (CEC) of the clay (0.8 mol(c)/kg clay), no measurable amount of MG remained in solution. The maximal amounts of MGOH(+) adsorbed were larger than those of MG(2+), being 1.15 and 0.75 mol MG/kg clay, respectively, corresponding to 140% of the CEC in the first case. On a charge basis the adsorption of added MG(2+) amounts to 185% of the CEC, which raises the possibility that a certain fraction of MG(2+) transformed into the monovalent form during the incubation period, since other divalent organic cations previously studied only adsorbed up to the CEC (paraquat), or slightly above it (diquat). Adsorption of MG on sepiolite (CEC=0.15 mol(c)/kg) further emphasizes the two patterns of its adsorption. The maximal adsorbed amounts of MG(2+) and MGOH(+) were 0.09 and 0.30 mol/kg clay, respectively. X-ray diffraction measurements gave lower values for the basal spacings for montmorillonite-MG(+) than for MGOH(+), suggesting that MG(2+) binds two clay platelets together, as in the case of other divalent cations. A competition for adsorption between MG and the monovalent organic cation, acriflavin (AF), gave lower adsorbed amounts of AF when competing with MG(+), which is interpreted to be due to the smaller basal spacing in this case, which partially inhibits the entry of AF molecules into the interlammelar space. Spectra of montmorillonite-MG particles in the visible range exhibited significant differences between clay-MG and clay-carbinol. Copyright 2000 Academic Press.

Journal Article↗

PubMed2000

Effect of phospholipid composition on an amphipathic peptide-mediated pore formation in bilayer vesicles.

To better understand the influence of phospholipid acyl-chain composition on the formation of pores by cytotoxic amphipathic helices in biological membranes, the leakage of aqueous contents induced by the synthetic peptide GALA (WEAALAEALAE ALAEHLAEALAEALEALAA) from large unilamellar phospholipid vesicles of various compositions has been studied. Peptide-mediated leakage was examined at pH 5.0 from vesicles made of phosphatidylcholine (PC) and phosphatidylglycerol (PG) with the following acyl-chain compositions: 1-palmitoyl-2-oleoyl (PO), 1,2-dioleoyl (DO), 1, 2-dielaidoyl (DE), and 1,2-dipetroselinoyl (DPe). A mathematical model predicts and simulates the final extents of GALA-mediated leakage of 1-aminonaphthalene-3,6,8-trisulfonic acid (ANTS) and p-xylene-bis-pyridinium bromide (DPX) from 1-palmitoyl-2-oleoyl-phosphatidylcholine/1-palmitoyl-2-oleoyl-phospha tidylglycerol (POPC/POPG) and 1, 2-dielaidoyl-sn-glycero-3-phosphocholine/1, 2-dielaidoyl-phosphatidylglycerol (DEPC/DEPG) liposomes at pH 5.0 as a function of peptide concentration in the bilayer, by considering that GALA pores responsible for this leakage have a minimum size of 10 +/- 2 monomers and are formed by quasiirreversible aggregation of the peptide. With the phospholipid acyl-chain compositions tested, GALA-induced ANTS/DPX leakage follows the rank order POPC/POPG approximately DEPC/DEPG > DPePC/DPePG > DOPC/DOPG. Results from binding experiments reveal that this reduced leakage from DOPC/DOPG vesicles cannot be explained by a reduced binding affinity of the peptide to these membranes. As shown by monitoring the leakage of a fluorescent dextran, an increase in the minimum pore size also does not explain the reduction in ANTS/DPX leakage. The data suggest that surface-associated GALA monomers or aggregates are stabilized in bilayers composed of phospholipids containing a cis unsaturation per acyl chain (DO and DPe), while transbilayer peptide insertion is reduced. GALA-induced ANTS/DPX leakage is also decreased when the vesicles contain phosphatidylethanolamine (PE). This lends further support to the suggestion that factors stabilizing the surface state of the peptide reduce its insertion and subsequent pore formation in the bilayer.

4-Chloro-7-nitrobenzofurazan↗

PubMed2000

Interactions of peptides with liposomes: pore formation and fusion.

Leakage from liposomes induced by several peptides is reviewed and a pore model is described. According to this model peptide molecules become incorporated into the vesicle bilayer and aggregate reversibly or irreversibly within the surface. When a peptide aggregate reaches a critical size, peptide translocation can occur and a pore is formed. With the peptide GALA the pores are stable and persist for at least 10 minutes. The model predicts that for a given lipid/peptide ratio, the extent of leakage should decrease as the vesicle diameter decreases, and for a given amount of peptide bound per vesicle less leakage would be observed at higher temperatures due to the increase in reversibility of surface aggregates of the peptide. Effect of membrane composition on pore formation is reviewed. When cholesterol was included in the liposomes the efficiency of inducation of leakage by the peptide GALA was reduced due to reduced binding and increased reversibility of surface aggregation of the peptide. Phospholipids which contain less ordered acyl-chains and have a slightly wedge-like shape, can better accommodate peptide surface aggregates, and consequently insertion and translocation of the peptide may be less favored. Demonstrations of antagonism between pore formation and fusion are presented. The choice of factors which promote vesicle aggregation, e.g., larger peptides, increased vesicle and peptide concentration results in enhanced vesicle fusion at the expense of formation of intravesicular pores. FTIR studies with HIV-1 fusion peptides indicate that in systems where extensive vesicle fusion occurred the beta conformation of the peptides was predominant, whereas the alpha conformation was exhibited in cases where leakage was the main outcome. Antagonism between leakage and fusion was exhibited by 1-palmitoyl-2-oleoylphosphatidylglycerol vesicles, where the order of addition of peptide (HIV(arg)) or Ca(2+)dictated whether pore formation or vesicle fusion would occur. The current study emphasizes that the addition of Ca(2+), which promotes vesicle aggregation can also reduce peptide translocation in isolated vesicles.

Coated Vesicles↗

PubMed2000

Montmorillonite-phenyltrimethylammonium yields environmentally improved formulations of hydrophobic herbicides.

This study aimed to design formulations of hydrophobic herbicides, alachlor and metolachlor, by adsorbing them on the clay mineral montmorillonite preadsorbed by the small organic cation phenyltrimethylammonium (PTMA). An adsorption model that considers electrostatics and specific binding and the possibility of cation adsorption above the cation exchange capacity (CEC) could explain and yield predictions for PTMA adsorption in the presence of NaCl concentrations from 0 to 500 mM. Adsorption of alachlor and metolachlor from aqueous solution on a clay mineral preadsorbed by PTMA was determined by GC and modeled by Langmuir equation. Herbicide interactions with the organoclay were studied by Fourier transform infrared spectroscopy. Leaching of herbicides was determined by a bioassay using a column technique and Setaria viridis as a test plant. The adsorbed amounts of alachlor and metolachlor on montmorillonite preadsorbed by PTMA at a loading of 0. 5 mol/kg (Mont-PTMA0.5) were higher than at a loading up to the CEC, that is, 0.8 mol/kg, and were higher than those obtained by using several other organic cations. Herbicide formulations based on Mont-PTMA0.5 yielded the largest shifts of the infrared peaks of the herbicides. These formulations based on Mont-PTMA0.5 gave slower release and showed improved weed control in comparison with formulations based on other organoclays. These formulations maintained herbicidal activity in the topsoil and yielded the most significant reduction in herbicide leaching.

Adsorption↗

PubMed2000

Organo-clay formulations of the hydrophobic herbicide norflurazon yield reduced leaching.

The study aimed to reduce leaching of the hydrophobic herbicide norflurazon (4-chloro-5-methylamino-2-(alpha,alpha, alpha)-trifluoro-m-tolylpyridazin-3-(2H)-one) by adsorbing it on clays or organo-clays. The surface of the clay mineral montmorillonite was modified from hydrophilic to hydrophobic by preadsorbing it with organic cations, of which thioflavin-T (TFT) at a loading corresponding to (5)/(8) of the cation-exchange capacity of the clay mineral yielded the highest affinity of adsorption of norflurazon. Pillared clay (PC) used without organic cations exhibited enhanced affinity for norflurazon adsorption, much higher than that of montmorillonite or sepiolite. Fourier transform infrared (FTIR) results showed interactions between aromatic moieties of preadsorbed TFT and the herbicide. Stronger interaction of the herbicide with a clay mineral or organo-clay corresponded to its slower release. Formulations prepared on the basis of montmorillonite-TFT and PC were more effective in reducing herbicide leaching in soil columns in comparison to the commercial formulation, whereas the herbicidal efficiencies were comparable.

Aluminum Silicates↗

PubMed2000

Photostabilization of the herbicide norflurazon by using organoclays.

Photostable formulations of the herbicide norflurazon [4-chloro-5-(methylamino)-2-(alpha,alpha, alpha-trifluoro-m-tolyl)pyridazin-3-(2H)-one] were achieved by adsorbing it on pillared clay or on montmorillonite preadsorbed with the organic cation thioflavin T (TFT). Diffuse reflectance Fourier transform infrared spectra showed the existence of strong interactions between the aromatic moieties of preadsorbed TFT and the herbicide, particularly after irradiation. The photostabilization of norflurazon obtained with TFT-clay was mainly due to energy transfer from the herbicide to the organic cation via pi-pi interactions. An additional mechanism is the lower production of radicals from the clay when the clay mineral surface is covered with the organic cation. These radicals are responsible for the enhanced photodegradation observed when norflurazon was irradiated in the presence of untreated montmorillonite.

Aluminum Silicates↗

PubMed2000

Rapid entry of bitter and sweet tastants into liposomes and taste cells: implications for signal transduction.

Some amphipathic bitter tastants and non-sugar sweeteners are direct activators of G proteins and stimulate transduction pathways in cells not related to taste. We demonstrate that the amphipathic bitter tastants quinine and cyclo(Leu-Trp) and the non-sugar sweetener saccharin translocate rapidly through multilamellar liposomes. Furthermore, when rat circumvallate (CV) taste buds were incubated with the above tastants for 30 s, their intracellular concentrations increased by 3.5- to 7-fold relative to their extracellular concentrations. The time course of this dramatic accumulation was also monitored in situ in rat single CV taste buds under a confocal laser-scanning microscope. Tastants were clearly localized to the taste cell cytosol. It is proposed that, due to their rapid permeation into taste cells, these amphipathic tastants may be available for activation of signal transduction components (e. g., G proteins) directly within the time course of taste sensation. Such activation may occur in addition to the action of these tastants on putative G protein-coupled receptors. This phenomenon may be related to the slow taste onset and lingering aftertaste typically produced by many bitter tastants and non-sugar sweeteners.

Animals↗

PubMed2000

Induction of aggregation and fusion of cholesterol-containing membrane vesicles by an anti-cholesterol monoclonal antibody.

A monoclonal IgM antibody that reacts with cholesterol was able to aggregate small and large unilamellar lipid vesicles. Vesicles aggregated by the antibody could be dispersed by trypsin digestion. Inclusion of unsaturated phosphatidylethanolamine in the vesicle formulation lowered the relative amount of cholesterol necessary for aggregation, and prevented disaggregation by trypsin treatment. Fluorimetric assays indicated that membrane mixing occurred in aggregates resistant to trypsinization, but the vesicles did not mix or leak their aqueous contents. Analysis of the kinetics of lipid-mixing showed an increase in the aggregation and fusion rate constants with increasing antibody concentrations, indicating that the antibody reaction promotes both processes. An apparent inactivation process whose rate increased with antibody dose has been considered. We conclude that the simultaneous binding of antibodies to more than one vesicle at densities that allow the contact of membrane surfaces, induces first aggregation followed by hemifusion, and with excess of antibody also results in inactivation of the latter process.

Antibodies, Monoclonal↗

PubMed1999

Mechanisms and kinetics of liposome-cell interactions.

Although the possibility of targeting drugs to specific tissues and cells, as well as facilitating their uptake and cytoplasmic delivery has rendered liposomes a versatile drug carrier system with numerous potential applications in medicine, the molecular mechanisms of liposome-cell interactions are not understood well. Here we have reviewed the early and current concepts of liposome-cell interactions, including possible liposome receptors. Uptake of liposomes by cells can be modified by the lipid composition, particularly by the inclusion of steric stabilizers such as PEG-conjugated lipids. Such modifications also alter the circulation time and biodistribution of liposomes, which can thus be tailored for particular applications. The intracellular fate of encapsulated molecules can be modified by the use of pH-sensitive liposomes which can also be sterically stabilized. Cationic liposomes that can undergo lipid mixing with cellular membranes can deliver complexed DNA to cells, but most likely via an endocytotic process. Kinetic analysis of liposome-cell interactions can elucidate the numbers of liposome receptors of several types and the corresponding binding constants. It is likely that liposomes bind to different cell surface receptors on different cells, and that they utilize more than one type of receptor on a particular cell. The kinetic analysis also provides the rate constants of endocytosis and the percentages of liposomes that are bound or endocytosed.

Journal Article↗

PubMed1999

Interaction of cationic liposomes and their DNA complexes with monocytic leukemia cells.

Cationic liposomes complexed with DNA have been used extensively as non-viral vectors for the intracellular delivery of reporter or therapeutic genes in culture and in vivo. We examined the relationship between the characteristics of the lipoplexes, their mode of interaction with monocytic THP-1 cells and their ability to transfect these cells. We determined the size and zeta potential of cationic liposomes (composed of 1,2-dioleoyl-3-(trimethylammonium) propane (DOTAP) and its mixtures with neutral lipids), and lipoplexes at different (+/-) charge ratios. As the (+/-) charge ratio of the lipoplexes decreased to (1/1), a significant reduction in zeta potential and an increase in size was observed. The increase in size resulted from fusion between liposomes promoted by DNA, as demonstrated by a lipid mixing assay, and from aggregation of the complexes. Interaction of liposomes and lipoplexes with THP-1 cells was assessed by monitoring lipid mixing ('fusion') as well as binding and cell association. While no lipid mixing was observed with the 1/2 (+/-) lipid/DNA complexes, lipoplexes with higher (+/-) charge ratios underwent significant fusion in conjunction with extensive cell binding. Liposome binding to cells was dependent on the positive charge of the liposomes, and their fusion could be modulated by the co-lipid. DOTAP/phosphatidylethanolamine (1:1) liposomes fused with THP-1 cells, unlike DOTAP/phosphatidylcholine (1:1) liposomes, although both liposome types bound to the cells to a similar extent. The use of inhibitors of endocytosis indicated that fusion of the cationic liposomes with cells occurred mainly at the plasma membrane level. The presence of serum increased the size of the cationic liposomes, but not that of the lipoplexes. Low concentrations of serum (3%) completely inhibited the fusion of cationic liposomes with cells, while inhibiting binding by only 20%. Our results suggest that binding of cationic liposomes and lipoplexes to cells is governed primarily by electrostatic interactions, whereas their fusion is regulated by the lipid composition and sterically favorable interactions with cell surface molecules. In addition our results indicate no correlation between fusion of the lipoplexes with the plasma membrane and the levels of transfection.

Binding, Competitive↗