Role Of Positive Charge Research Articles

DNA interaction, anti-proliferative effect of copper oxide nanocolloids prepared from metallosurfactant based microemulsions acting as precursor, template and reducing agent

In the present study, we have synthesized mixed cuprous/copper oxide nanosuspensions by metallosurfactant based microemulsion technique. Three metallosurfactants were synthesized which includes two non-ionic double chained metallosurfactants with C12, C16 chains with coordinated copper i.e. Cudda and Cuhexa, respectively. Another cationic double chained metallosurfactant with loosely bound metal (Cuctac) was also prepared. The prepared metallocomplexes were characterized using FTIR, elemental analysis, and NMR. The effect of the position of metallosurfactant in microemulsion on the fabrication and properties of nanosuspensions was elucidated. In this method, no external reducing agent and capping agent were added and tween 80 acted both as reducing and stabilizing agent for the nanoparticles. The synthesized nanoparticles were characterized and it was observed that mixed copper and cuprous oxide particles are present in colloidal suspension for all the three studied metallosurfactants. The kinetics of formation of mixed copper/cuprous oxide nanosuspensions (Ns) and their stability was estimated using Uv-visible spectroscopy. Further, the binding and interactions of copper nanosuspensions with calf Thymus DNA (CT-DNA) were assessed using Uv–vis spectroscopy, circular dichroism and gel electrophoresis. Additionally, the antioxidant activity of the Cu Ns was checked using DPPH assay. The role of positive charge on nanoparticles as evaluated from Zeta potential was responsible for DNA affinity. The DNA conformational changes in the presence of nanosuspensions and relevant scavengers were investigated. Further, the anti-proliferative activity of copper Ns was assessed using HeLa cells and Cuhexa derived Ns were proved to be active with highest activity at a low concentration and were nontoxic towards normal cell lines. In summary, this work demonstrates a softer approach for the synthesis of copper nanosuspensions with a size range of 2–5 nm and evaluated the role of type and structure of metallosurfactant on size, stability of particles and anti-proliferative activity.

Electrical conduction in polyethylene: The role of positive charge and the formation of positive packets

A model for positive hole transport in polyethylene is developed which takes particular account of the crystalline-amorphous morphology of the polymer. The significant feature is the employment of super-exchange quantum mechanical tunneling to explain hole transport through the amorphous phase. The consequence is that the hole mobility exhibits a maximum as a function of the electric field, a manifestation of the inverse Marcus effect. It is shown that this feature accounts for the majority of the reported high-field hole transport effects in polyethylene, including packet formation.

Role of positive charge of lysine residue on cytochrome c3for electrostatic interaction with hydrogenase

Cytochrome c3from Desulfovibrio vulgaris (Miyazaki) is an electron transfer protein containing four hemes per molecule. Its physiological electron transfer partner is the hydrogenase which catalyzes reversible oxidation of hydrogen. The complex formation between cytochrome c3and hydrogenase is caused by electrostatic interaction, because cytochrome c3is a basic protein and hydrogenase is an acidic protein. As cytochrome c3has 20 lysine residues among 108 amino acids, the positive charges of some lysine residues may play an important role in the interaction with hydrogenase. To clarify the role of positive charge of lysine residue, the positive charge was changed to neutral or negative charge using chemical modification and site-directed mutagenesis. When the positive charges around heme IV were changed, the hydrogen evolution rate with hydrogenase decreased. The affinity between hydrogenase and mutated cytochrome c3(K57Q, K57E, K72Q, K94Q, K94E) were not affected. On the other hand, the affinity of K72E cytochrome c3for hydrogenase was very low. These results suggest that the positive charge around heme IV plays an important role in the electrostatic interaction with hydrogenase in hydrogen evolution.

Serine Base Exchange Enzyme Activity Is Modulated by Sphingosine and Other Amphiphilic Compounds: Possible Role of Positive Charge in Increasing the Synthesis of Phosphatidylserine

It has been found that sphingosine and sphingosylphosphorylcholine (amphiphilic cations) have a stimulatory, and cholesterol 3-sulfate (an amphiphilic anion), an inhibitory, effect on [14C]serine incorporation into phosphatidylserine in glioma C6 and rat liver microsomes. In glioma intact cells sphingosine stimulates phosphatidylserine synthesis in a process independent of protein kinase C, but suppressed by thapsigargin. We suggest that the stimulation of the enzyme occurs by the interaction of amphiphilic cations with the membrane cosubstrate phospholipids, leading to a charge redistribution on their phosphate groups, and hence facilitating the enzyme action. A new hypothesis concerning the mechanism of the serine base exchange reaction is discussed.

Role of positive charge in the competitive effect of phosphate on sulfate sorption by an allophanic soil

The effect of phosphate (P) on the sorption of sulfate (S) by an allophanic soil with high surface positive charge was investigated in the pH range of 5.3-7.0 obtained by incubation with Ca(OH)2. The effect of P on S sorption was directly related to the effect of P on surface positive charge. At low soil pH, P reduced surface positive charge to a larger extent than at high pH and this was associated with a larger effect of P on S sorption.

Role of positive charge on the amino-terminal region of the signal peptide in protein secretion across the membrane

Role of positive charge on the amino-terminal region of the signal peptide in protein secretion across the membrane

Role of positive charge on the amino-terminal region of the signal peptide in protein secretion across the membrane

Role of positive charge on the amino-terminal region of the signal peptide in protein secretion across the membrane

Role of positive charge on the amino-terminal region of the signal peptide in protein secretion across the membrane.

The positively charged amino-terminal region of the signal peptide has been proposed to have an important role at an initial step of protein secretion across the membrane (loop model). To test this hypothesis, the charge on the amino-terminal region of the signal peptide of the prolipoprotein of the Escherichia coli outer membrane was altered by using synthetic oligonucleotides from +2 to +1, 0, and -1 by guided site specific mutagenesis of a plasmid DNA carrying an inducible lipoprotein gene. The wild-type sequence of this sectio, Met-Lys-Ala-Thr-Lys (+2), was thus changed to Met-Lys-Asp-Thr-Lys (I-1; +1), Met-Ala-Thr-Lys (I-2; +1), Met-Asp-Thr-Lys (I-3; 0), and Met-Glu-Asp-Thr-Lys (I-4; -1). After induction of lipoprotein production, cells were pulse labeled with [35S]methionine for 10 sec. The lipoprotein of I-1, I-2, and I-3 was assembled in the membrane, although the rates of lipoprotein production progressively decreased as the charge on the signal peptide became more negative. Conversely, in the case of I-4, only a small amount of lipoprotein assembled in the membrane while a large amount of glycerol-unmodified prolipoprotein accumulated in the cytoplasm. This soluble prolipoprotein was gradually and posttranslationally secreted across the membrane to be modified and assembled in the membrane. These results indicate that the positively charged amino-terminal region of the signal peptide plays an important role in efficient protein secretion across the membrane.