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PubMed2005

Electrostatically driven spatial patterns in lipid membrane composition.

To explore the physical mechanisms that can guide spatial organization at biological membranes, we have constructed simple, cell-free intermembrane junctions. We find that the mechanically driven patterning of proteins uncovered in our earlier work can electrostatically generate spatial patterns in the distribution of charged membrane lipids. Tuning the magnitude of the interaction as a function of composition and ionic strength, and analyzing the interplay between thermodynamics and electrostatics via a Poisson-Boltzmann approach, we are able to determine the charge density and surface potential of the junction components. Surprisingly, the electrostatic potential of the proteins is a minor factor in the lipid reorganization; the protein size and its modulation of the junction topography play the dominant role in driving the electrostatic patterns.

Lipid Bilayers↗
PubMed1992

Electrostatic properties of 1-methyluracil from diffraction data.

1-Methyluracil (1-methyl-2,4-dioxopyrimidine), C5H6-N2O2, M(r) = 126.12, orthorhombic, Ibam, a = 13.188 (6), b = 13.175 (5), c = 6.214 (3) A, V = 1079.7 (8) A3, Z = 8, Dx = 1.552 g cm-3, lambda (Mo K alpha) = 0.7107 A, mu = 1.317 cm-1, F(000) = 528, T = 123 K, R(F2) = 0.068 for 2996 reflections with sin theta/lambda less than 1.08 A-1. The electronic charge-density distribution has been analyzed in terms of Stewart's rigid pseudoatom model, using restricted Slater radial functions and angular multipole terms extending to octapoles for C, N and O, and quadrupoles for H pseudoatoms. Three different structure refinements have been carried out based on two X-ray diffraction data sets from different crystals collected at temperatures differing by about 20 K. The molecular dipole moment is 6.4 (27) D. Maps of the electrostatic potential for a molecule isolated from the crystal show that atoms O2 and O4 confer overall electro-negativity on one side of the molecule while the CH groups and the C1 methyl group confer electropositivity on the other. For the centrosymmetric hydrogen-bonded dimer (N3-H3...O4'; H...O distances 1.77 A) the electrostatic potential shows electropositive bridges between the molecules. These features are lacking for the C-H...O interactions (distances H6...O2, 2.37; H11...O4, 2.34 A). The electron density and its Laplacian have been determined at the intramolecular bond-critical points and also for the intermolecular H...O interactions. Values for the former are characteristic of covalent bonds. Values of the electron density and Laplacian for the C-H...O interactions are very small and have little or no significance in terms of their e.s.d.'s. The electrostatic energy of interaction for the N-H...O hydrogen-bonded dimer is -10 (12) kJ mol-1. The attractive electrostatic energy increases to -67 (33) kJ mol-1 for a centrosymmetric planar tetramer in which the C-H...O interactions are also formed.

Calorimetry↗
PubMed2006

Simple electrostatic model improves designed protein sequences.

Electrostatic interactions are important for both protein stability and function, including binding and catalysis. As protein design moves into these areas, an accurate description of electrostatic energy becomes necessary. Here, we show that a simple distance-dependent Coulombic function parameterized by a comparison to Poisson-Boltzmann calculations is able to capture some of these electrostatic interactions. Specifically, all three helix N-capping interactions in the engrailed homeodomain fold are recovered using the newly parameterized model. The stability of this designed protein is similar to a protein forced by sequence restriction to have beneficial electrostatic interactions.

Amino Acid Sequence↗
PubMed1988

Electrostatic potential of macromolecules measured by pKa shift of a fluorophore. 2. Transfer RNA.

The procedures developed earlier (Friedrich and Woolley, preceding paper in this journal) for probing electrostatic potential with the fluorescein label were applied to transfer RNA. By using tRNA species that contain chemically reactive bases we were able to label these bases with fluorescein derivatives and thus to 'map' the electrostatic potential around the molecule. Both the electrostatic potential and the fluorescence emission anisotropy data that were obtained at the same time could be understood in terms of the well-known, paradigmatic crystal structure of tRNA(Phe). However, within the distribution of the various tRNA species, tRNA(Met)f appeared to occupy an extreme position, which suggests a relation between the conformation in solution and the initiation function of this molecule. Comparison with theoretical predictions by others of the electrostatic potential map of tRNA showed agreement in respect of trends, but the values of the potentials measured were orders of magnitude lower than predicted. This we attribute primarily to solvation.

Electrochemistry↗
PubMed2005

The effects of intervention with local electrostatic air cleaners on airborne dust and the health of office employees.

UNLABELLED: The aim of this intervention study was to identify any health improvements in the upper and lower airways of office workers after the installation of local electrostatic air cleaners. Eighty persons with airways symptoms were recruited and randomly assigned to an intervention or control group. Half of the air cleaners had a non-functioning electrostatic unit. Both participants and field researchers were blinded to the group status. Subjective symptoms were recorded using a questionnaire, and indexes calculated for general, irritation and skin symptoms. Objective respiratory health indicators were recorded, with acoustic rhinometry and peak expiratory flow (PEF) meters. In the intervention group there was a decrease in mean dust concentration from 65 to 35 microg/m(3), and a reduction from 57 to 47 microg/m(3) in the control group (P < 0.05 for difference in decline). The reduction was observed for all particles sizes. The irritation and general symptom indices decreased in both groups, but there was no improvement in the intervention group, compared with the control group. Median PEF increased 3 ml/s in the intervention group, and decreased 4 ml/s in the control group. The adjusted odds ratio for an increase above the 70th percentile was 5.7 (95% CI 1.0-32). PRACTICAL IMPLICATIONS: Electrostatic air cleaners can reduce the dust concentration effectively in the office environment. Small, medium and large sized particles can be reduced by approximately 50%, relatively most effectively for the respirable particles. However, the air cleaners tested in this study produced an annoying fan noise. Cleaning efficiency and noise data should be given consideration before installation. This experimental field study suggests that office workers with airways symptoms may benefit from installation of local electrostatic air cleaners.

Adult↗
PubMed1995

A molecular model of proteoglycan-associated electrostatic forces in cartilage mechanics.

Measured values of the swelling pressure of charged proteoglycans (PG) in solution (Williams RPW, and Comper WD; Biophysical Chemistry 36:223, 1990) and the ionic strength dependence of the equilibrium modulus of PG-rich articular cartilage (Eisenberg SR, and Grodzinsky AJ; J Orthop Res 3: 148, 1985) are compared to the predictions of two models. Each model is a representation of electrostatic forces arising from charge present on spatially fixed macromolecules and spatially mobile micro-ions. The first is a macroscopic continuum model based on Donnan equilibrium that includes no molecular-level structure and assumes that the electrical potential is spatially invariant within the polyelectrolyte medium (i.e. zero electric field). The second model is based on a microstructural, molecular-level solution of the Poisson-Boltzmann (PB) equation within a unit cell containing a charged glycosaminoglycan (GAG) molecule and its surrounding atmosphere of mobile ions. This latter approach accounts for the space-varying electrical potential and electrical field between the GAG constituents of the PG. In computations involving no adjustable parameters, the PB-cell model agrees with the measured pressure of PG solutions to within experimental error (10%), whereas the ideal Donnan model overestimates the pressure by up to 3-fold. In computations involving one adjustable parameter for each model, the PB-cell model predicts the ionic strength dependence of the equilibrium modulus of articular cartilage. Near physiological ionic strength, the Donnan model overpredicts the modulus data by 2-fold, but the two models coincide for low ionic strengths (C0 < 0.025M) where the spatially invariant Donnan potential is a closer approximation to the PB potential distribution. The PB-cell model result indicates that electrostatic forces between adjacent GAGs predominate in determining the swelling pressure of PG in the concentration range found in articular cartilage (20-80 mg/ml). The PB-cell model is also consistent with data (Eisenberg and Grodzinsky, 1985, Lai WM, Hou JS, and Mow VC; J Biomech Eng 113: 245, 1991) showing that these electrostatic forces account for approximately 1/2 (290kPa) the equilibrium modulus of cartilage at physiological ionic strength while absolute swelling pressures may be as low as approximately 25-100kPa. This important property of electrostatic repulsion between GAGs that are highly charged but spaced a few Debye lengths apart allows cartilage to resist compression (high modulus) without generating excessive intratissue swelling pressures.

Animals↗
PubMed1999

The cavity and pore helices in the KcsA K+ channel: electrostatic stabilization of monovalent cations.

The electrostatic influence of the central cavity and pore alpha helices in the potassium ion channel from Streptomyces lividans (KcsA K+ channel) was analyzed by solving the finite difference Poisson equation. The cavity and helices overcome the destabilizing influence of the membrane and stabilize a cation at the membrane center. The electrostatic effect of the pore helices is large compared to that described for water-soluble proteins because of the low dielectric membrane environment. The combined contributions of the ion self-energy and the helix electrostatic field give rise to selectivity for monovalent cations in the water-filled cavity. Thus, the K+ channel uses simple electrostatic principles to solve the fundamental problem of ion destabilization by the cell membrane lipid bilayer.

Bacterial Proteins↗
PubMed1995

Classical electrostatics in biology and chemistry.

A major revival in the use of classical electrostatics as an approach to the study of charged and polar molecules in aqueous solution has been made possible through the development of fast numerical and computational methods to solve the Poisson-Boltzmann equation for solute molecules that have complex shapes and charge distributions. Graphical visualization of the calculated electrostatic potentials generated by proteins and nucleic acids has revealed insights into the role of electrostatic interactions in a wide range of biological phenomena. Classical electrostatics has also proved to be successful quantitative tool yielding accurate descriptions of electrical potentials, diffusion limited processes, pH-dependent properties of proteins, ionic strength-dependent phenomena, and the solvation free energies of organic molecules.

Biochemistry↗
PubMed1996

Effect of electrostatic charge, flow, delay and multiple actuations on the in vitro delivery of salbutamol from different small volume spacers for infants.

BACKGROUND: A study was undertaken to determine the influences of electrostatic charge, flow, delay, and multiple actuations on the in vitro delivery of salbutamol generated by a pressurised metered dose inhaler (pMDI) from small volume spacers used in infants. METHODS: Ten actuations from a salbutamol pMDI were drawn at different flow rates after either single or multiple actuations, with or without delay, through either static or reduced static spacers. An ionic detergent was used to reduce the charge of plastic spacers (Babyhaler, Babyspacer, Aerochamber, Nebuhaler). Electrostatic charge was measured using an electrometer. A multistage liquid impinger was used to determine the particle size distribution of the output of the pMDI through the spacers. RESULTS: Electrostatic charge on the surface of plastic spacers had the greatest influence on delivery, causing a decrease in drug delivery. Reducing charge by coating the surface with ionic detergent resulted in an increase of 46.5-71.1% (p < 0.001) in small (< 6.8 microns) particle delivery from small volume plastic spacers. Lower flow, delay, and multiple actuations resulted in decreased delivery from static spacers. Lower flow resulted in a decrease of 15% in small (< 9.6 microns) particle delivery. Delay and multiple actuations resulted in a decrease of 40.7% and 76.0%, respectively, in small (< 6.8 microns) particle delivery. The influences of lower flow, delay, and multiple actuations were greatly reduced or even eliminated by reducing charge. However, multiple actuations still resulted in a significant decreased delivery (p < 0.05). The reduced static Nebuhaler had a higher delivery than all small volume spacers. CONCLUSIONS: Electrostatic charge has a major influence on the delivery of salbutamol from small volume spacers. Using a metal spacer or ionic detergent coating of plastic spacers resulted in no or reduced charge and hence in improved delivery. Lower flow, delay, and multiple actuations played a major part only in static spacers.

Albuterol↗
PubMed1999

Investigation of the phenomenon of electrostatic compromise of a plastic fiber heat exchanger.

The use of a new generation of blood oxygenator design using plastic fibers for the heat exchange material is growing. The benefits of a plastic heat exchange material are improved biocompatibility and performance over some of the traditional metals used. During the initial period of clinical use of one of these new oxygenators, there were reports of four blood-to-water leaks. No patient complications were associated with these leaks, but the product was withdrawn from the market. After a thorough evaluation, the cause of the leaks was found to be an electrostatic discharge that occurred within the heat exchanger during priming of the extracorporeal circuit. It was found that an electrostatic potential between the blood path and the water path of the heat exchanger is generated as the prime solution is recirculated by a roller pump with polyvinyl chloride (PVC) pumphead tubing. The magnitude of the potential generated was found to vary with the make and model of the roller pump. If this voltage exceeds the dielectric strength of the fiber, a discharge through the wall of a single heat exchange fiber will occur and produce a hole. Several solutions to this problem of roller pumps generating an electrostatic charge when used with PVC pumphead tubing were identified. Centrifugal blood pumps and roller pumps using silicone rubber pumphead tubing were found to generate no significant electrostatic potential between the blood path and the water path. Another solution, a charge equalization line (CEL), was designed to provide a conductive path for the charge to equilibrate across the fiber wall. The CEL can be either external or internal to the oxygenator. Each of these solutions was validated and the product has been reintroduced for clinical use.

Equipment Design↗
PubMed1999

Study on causes and prevention of electrostatic charge build-up during extracorporeal circulation.

For many years it has been known that roller pumps interfere regularly with the electrocardiogram (ECG) signal. This electrical activity is also considered responsible for the electrostatic charge build-up in some oxygenators with a plastic heat exchanger. During use of such an oxygenator, an electrical shock can be felt when touching the device. In the absence of a provoked discharge, a spontaneous discharge may occur. The construction of the heat exchanger and the use of nonconductive materials enable some devices to function as a capacitor. If the voltage difference across the fibre wall is too high, an electrostatic discharge may occur. In 1997, four blood-to-water leaks in Maxima Forté oxygenators were reported on a worldwide basis. After thorough research by Medtronic Cardiac Surgery (Cardiopulmonary Division), the cause of the leaks was found to be an electrothermal event across the fibre wall of one single fibre. No patient injuries were reported in any of the events. Medtronic patented a number of US Food and Drug Administration-approved and patient-safe solutions to prevent this electrostatic charge build-up. We studied the electrostatic phenomenon in order to clarify the clinical aspects. The in vitro part of the study is related to the behaviour of the Medtronic Biopump and the Stockert Shiley roller pump--in combination with the use of a PVC or silicone pumpheader. Subsequently, we have investigated the influence of the rotation or flow of both types of blood pumps and occlusion settings on the roller pump. Furthermore, we tried to capture the electrical charge generated by the roller pumps in a capacitor and in some oxygenators with different types of heat exchanger. Finally, we tested the external CEL (Charge Equalization Line) and the internal 'Gold Wire' charge equalization systems, both patented by Medtronic. In the in vivo part of the study, 15 patients were divided into three groups of five patients each. In the first group a roller pump with a PVC pumpheader was evaluated and, in the second group, a roller pump with a silicone pumpheader. The third group consisted of the Medtronic Biopump. In all the groups, a Maxima Forté oxygenator with the external CEL protection was used. Owing to the fact that, at the time, the Maxima Forté 'Gold Wire' oxygenator was not available for clinical use, only the external CEL could be evaluated.

Electric Injuries↗
PubMed2006

Electrostatic design of protein-protein association rates.

De novo design and redesign of proteins and protein complexes have made promising progress in recent years. Here, we give an overview of how to use available computer-based tools to design proteins to bind faster and tighter to their protein-complex partner by electrostatic optimization between the two proteins. Electrostatic optimization is possible because of the simple relation between the Debye-Huckel energy of interaction between a pair of proteins and their rate of association. This can be used for rapid, structure-based calculations of the electrostatic attraction between the two proteins in the complex. Using these principles, we developed two computer programs that predict the change in k(on), and as such the affinity, on introducing charged mutations. The two programs have a web interface that is available at www.weizmann.ac.il/home/bcges/PARE.html and http://bip.weizmann.ac.il/hypare . When mutations leading to charge optimization are introduced outside the physical binding site, the rate of dissociation is unchanged and therefore the change in k(on) parallels that of the affinity. This design method was evaluated on a number of different protein complexes resulting in binding rates and affinities of hundreds of fold faster and tighter compared to wild type. In this chapter, we demonstrate the procedure and go step by step over the methodology of using these programs for protein-association design. Finally, the way to easily implement the principle of electrostatic design for any protein complex of choice is shown.

Binding Sites↗
PubMed2006

Electrostatic steering at acetylcholine binding sites.

The electrostatic environments near the acetylcholine binding sites on the nicotinic acetylcholine receptor (nAChR) and acetylcholinesterase were measured by diffusion-enhanced fluorescence energy transfer (DEFET) to determine the influence of long-range electrostatic interactions on ligand binding kinetics and net binding energy. Changes in DEFET from variously charged Tb3+ -chelates revealed net potentials of -20 mV at the nAChR agonist sites and -14 mV at the entrance to the AChE active site, in physiological ionic strength conditions. The potential at the alphadelta-binding site of the nAChR was determined independently in the presence of d-tubocurarine to be -14 mV; the calculated potential at the alphagamma-site was approximately threefold stronger than at the alphadelta-site. By determining the local potential in increasing ionic strength, Debye-Hückel theory predicted that the potentials near the nAChR agonist binding sites are constituted by one to three charges in close proximity to the binding site. Examination of the binding kinetics of the fluorescent acetylcholine analog dansyl-C6-choline at ionic strengths from 12.5 to 400 mM revealed a twofold decrease in association rate. Debye-Hückel analysis of the kinetics revealed a similar charge distribution as seen by changes in the potentials. To determine whether the experimentally determined potentials are reflected by continuum electrostatics calculations, solutions to the nonlinear Poisson-Boltzmann equation were used to compute the potentials expected from DEFET measurements from high-resolution models of the nAChR and AChE. These calculations are in good agreement with the DEFET measurements for AChE and for the alphagamma-site of the nAChR. We conclude that long-range electrostatic interactions contribute -0.3 and -1 kcal/mol to the binding energy at the nAChR alphadelta- and alphagamma-sites due to an increase in association rates.

Acetylcholine↗
PubMed2006

Quantitative membrane electrostatics with the atomic force microscope.

The atomic force microscope (AFM) is sensitive to electric double layer interactions in electrolyte solutions, but provides only a qualitative view of interfacial electrostatics. We have fully characterized silicon nitride probe tips and other experimental parameters to allow a quantitative electrostatic analysis by AFM, and we have tested the validity of a simple analytical force expression through numerical simulations. As a test sample, we have measured the effective surface charge density of supported zwitterionic dioleoylphosphatidylcholine membranes with a variable fraction of anionic dioleoylphosphatidylserine. The resulting surface charge density and surface potential values are in quantitative agreement with those predicted by the Gouy-Chapman-Stern model of membrane charge regulation, but only when the numerical analysis is employed. In addition, we demonstrate that the AFM can detect double layer forces at a separation of several screening lengths, and that the probe only perturbs the membrane surface potential by <2%. Finally, we demonstrate 50-nm resolution electrostatic mapping on heterogeneous model membranes with the AFM. This novel combination of capabilities demonstrates that the AFM is a unique and powerful probe of membrane electrostatics.

Algorithms↗
PubMed2006

Recognition of ribonuclease A by 3'-5'-pyrophosphate-linked dinucleotide inhibitors: a molecular dynamics/continuum electrostatics analysis.

The proteins of the pancreatic ribonuclease A (RNase A) family catalyze the cleavage of the RNA polymer chain. The development of RNase inhibitors is of significant interest, as some of these compounds may have a therapeutic effect in pathological conditions associated with these proteins. The most potent low molecular weight inhibitor of RNase reported to date is the compound 5'-phospho-2'-deoxyuridine-3-pyrophosphate (P-->5)-adenosine-3-phosphate (pdUppA-3'-p). The 3',5'-pyrophosphate group of this compound increases its affinity and introduces structural features which seem to be unique in pyrophosphate-containing ligands bound to RNase A, such as the adoption of a syn conformation by the adenosine base at RNase subsite B(2) and the placement of the 5'-beta-phosphate of the adenylate (instead of the alpha-phosphate) at subsite P(1) where the phosphodiester bond cleavage occurs. In this work, we study by multi-ns molecular dynamics simulations the structural properties of RNase A complexes with the ligand pdUppA-3'-p and the related weaker inhibitor dUppA, which lacks the 3' and 5' terminal phosphate groups of pdUppA-3'-p. The simulations show that the adenylate 5'-beta-phosphate binding position and the adenosine syn orientation constitute robust structural features in both complexes, stabilized by persistent interactions with specific active-site residues of subsites P(1) and B(2). The simulation structures are used in conjunction with a continuum-electrostatics (Poisson-Boltzmann) model, to evaluate the relative binding affinity of the two complexes. The computed relative affinity of pdUppA-3'-p varies between -7.9 kcal/mol and -2.8 kcal/mol for a range of protein/ligand dielectric constants (epsilon(p)) 2-20, in good agreement with the experimental value (-3.6 kcal/mol); the agreement becomes exact with epsilon(p) = 8. The success of the continuum-electrostatics model suggests that the differences in affinity of the two ligands originate mainly from electrostatic interactions. A residue decomposition of the electrostatic free energies shows that the terminal phosphate groups of pdUppA-3'-p make increased interactions with residues Lys(7) and Lys(66) of the more remote sites P(2) and P(0), and His(119) of site P(1).

Adenosine Monophosphate↗
PubMedDate not supplied

Detection of airborne Salmonella enteritidis in the environment of experimentally infected laying hens by an electrostatic sampling device.

Bacteriologic culturing of environmental samples taken from sources such as manure pits and egg belts has been the principal screening tool in programs for identifying commercial laying flocks that have been exposed to Salmonella enteritidis and are thus at risk to produce contaminated eggs. Because airborne dust and aerosols can carry bacteria, air sampling offers a potentially efficient and inexpensive alternative for detecting S. enteritidis in poultry house environments. In the present study, an electrostatic air sampling device was applied to detect S. enteritidis in a room containing experimentally infected, caged laying hens. After oral inoculation of hens with a phage type 13a S. enteritidis strain, air samples were collected onto agar plates with the electrostatic sampling device, an impaction air sampler, and by passive exposure to the settling of aerosols and dust. Even though the floor of the room was cleaned once per week (removing most manure, dust, and feathers), air samples were positive for S. enteritidis for up to 4 wk postinoculation. On the basis of both the number of S. enteritidis colonies observed on incubated agar plates and the frequency of positive results, the efficiency of the electrostatic device was significantly greater than that of the passive exposure plates (especially at short collection intervals) and was similar to that of the far more expensive impaction sampler. The electrostatic device, used for a 3-hr sampling interval, detected airborne S. enteritidis on 75% of agar plates over the 4 wk of the study.

Air Microbiology↗
PubMed2002

Role of electrostatic and hydrophobic interactions in Ca(2+)-dependent phospholipid binding by the C(2)A-domain from synaptotagmin I.

Most C(2)-domains bind to phospholipid bilayers as a function of Ca(2+). Although phospholipid binding is central for the normal functions of C(2)-domain proteins, the precise mechanism of phospholipid binding is unclear. One of the key questions is whether phospholipid binding by C(2)-domains is primarily governed by electrostatic or hydrophobic interactions. We have now examined this question for the C(2)A-domain of synaptotagmin I, a membrane protein of secretory vesicles with an essential function in Ca(2+)-triggered exocytosis. Our results confirm previous data showing that Ca(2+)-dependent phospholipid binding by the synaptotagmin C(2)A-domain is exquisitely sensitive to ionic strength, suggesting an essential role for electrostatic interactions. However, we find that hydrophobic interactions mediated by exposed residues in the Ca(2+)-binding loops of the C(2)A-domain, in particular methionine 173, are also essential for tight phospholipid binding. Furthermore, we demonstrate that the apparent Ca(2+) affinity of the C(2)A-domain is determined not only by electrostatic interactions as shown previously, but also by hydrophobic interactions. Together these data indicate that phospholipid binding by the C(2)A-domain, although triggered by an electrostatic Ca(2+)-dependent switch, is stabilized by a hydrophobic mechanism. As a result, Ca(2+)-dependent phospholipid binding proceeds by a multimodal mechanism that mirrors the amphipathic nature of the phospholipid bilayer. The complex phospholipid binding mode of synaptotagmins may be important for its role in regulated exocytosis of secretory granules and synaptic vesicles.

Amino Acid Sequence↗
PubMed1984

Electrostatic fixed charge distribution in the RBC-glycocalyx and their influence upon the total free interaction energy.

On the basis of a recently developed biophysical model of cell-cell interaction, including electrostatic, electrodynamic, steric and bonding/bridging interaction energies the influence of different fixed charge (dissociated groups of the glycocalyx) density distributions in red blood cell (RBC) glycocalyces on the total free interaction energy was investigated. An analytical equation of electrostatic free energy on the basis of the linear Poisson-Boltzmann approach taking into account arbitrary distributions of fixed glycocalyx charges was obtained and corresponding free electrostatic energies of three example distributions were calculated. The electrodynamic, steric and bonding/bridging energies were computed as usual. It was shown that the free energy as a function of interaction distances strongly depends on the charge distribution and, correspondingly, the "weight" of this energy term in the total free interaction energy balance equation. Generally, it can be stated that as more charges are assumed to be fixed in the outer layer of RBC glycocalyx as more important becomes the electrostatic energy in contrast to the remaining three terms.

Electricity↗