cytochrome-c-t and 1-2-dipalmitoylphosphatidylglycerol

Non-fluidic bio-layer interferometry (BLI) has rapidly become a standard tool for monitoring almost all biomolecular interactions in a label-free, real-time and high-throughput manner. High-efficiency screening methods which measure the kinetics of liposomes with a variety of compounds require the immobilization of liposomes. In this work, a method is described for immobilizing liposomes for interaction studies, based on the biophysical principles of this biosensor platform. The immobilization approach includes the loading of DSPE-PEG

Topics: 1,2-Dipalmitoylphosphatidylcholine; Adsorption; Biosensing Techniques; Biotin; Cardiolipins; Cytochromes c; Drosophila Proteins; Fluoresceins; Fluorescent Dyes; High-Throughput Screening Assays; Hydrophobic and Hydrophilic Interactions; Interferometry; Kinetics; Liposomes; Micelles; Microscopy, Fluorescence; Phosphatidylcholines; Phosphatidylethanolamines; Phosphatidylglycerols; Polyethylene Glycols; Protein Phosphatase 1; Reproducibility of Results

This study investigates the development of a method for obtaining cytochrome C-containing liposomes (LS-Cyt), and evaluates their stability and specific activity. LS-Cyt were intended for the therapy of ophthalmic diseases. LS-Cyt were prepared by high pressure homogenization technique and lyophilized to obtain freeze-dried LS-Cyt. It was proposed to use anionic phospholipid- dipalmitoylphosphatidylglycerol (DPPG-Na) and phosphatidylcholine (PC) in a nanoparticulate composition. Were investigated various concentrations of lactose and trehalose as cryoprotectants. Samples with a lactose concentration of 6% showed the best results in terms of the emulsion formation time, encapsulation and preservation of nanosize. The main technological parameters for the obtained freeze-dried LS-Cyt were encapsulation of no less than 95% of cytochrome C (Cyt C), particle size of 140-170 nm, pH of 6.85±0.1, osmolarity of 330±3 mOsmol/kg, a lysophosphatidylcholine content (LPC) of 0.65±0.05 % of the total of lipids. Stability of the freeze-dried LS-Cyt during storage was established. The freeze-dried LS-Cyt was kept for 1 year in a light protected place at the temperature of -15 °C. No changes in the composition of LS-Cyt samples were detected over the observation period. Preclinical in-vivo research was conducted, namely the evaluation of specific activity on the model of the penetrating corneal injury. It was established that use of LS-Cyt contributes to a more rapid process of tissue regeneration and reduction of the inflammatory response in comparison with a non-liposomal dosage form.

Topics: Animals; Chemistry, Pharmaceutical; Corneal Injuries; Cytochromes c; Disease Models, Animal; Drug Stability; Drug Storage; Emulsions; Excipients; Female; Freeze Drying; Liposomes; Nanoparticles; Osmolar Concentration; Particle Size; Phosphatidylcholines; Phosphatidylglycerols; Phospholipids; Rabbits

Electronically enhanced chiral SFG spectroscopy was employed to study the lipid bound cyt c in situ. It was directly observed that upon interacting with anionic phospholipids, the amino acid residues around the heme adopted the β-sheet conformation. In addition, the orientation of this newly formed β-sheet structure was found to be sensitive to the bulk pH.

Topics: Animals; Cattle; Cytochromes c; Hydrogen-Ion Concentration; Lipids; Phosphatidylglycerols; Protein Structure, Secondary; Spectrum Analysis, Raman

In aqueous solution, while cytochrome c is a stably folded protein with a tightly packed structure at the secondary and tertiary levels, its heme-free precursor, apocytochrome c, shows all features of a structureless random coil. However, upon interaction with phospholipid vesicles or lysophospholipid micelles, apocytochrome c undergoes a conformational transition from its random coil in solution to an alpha-helical structure on association with lipid. The driving forces of this lipid-induced folding process of apocytochrome c were investigated for the interaction with various phospholipids and lysophospholipids. Binding of apocytochrome c to negatively charged phospholipid vesicles induced a partially folded state with approximately 85% of the alpha-helical structure of cytochrome c in solution. In contrast, in the presence of zwitterionic phospholipid vesicles, apocytochrome c remains a random coil, suggesting that negatively charged phospholipid headgroups play an important role in the mechanism of lipid-induced folding of apocytochrome c. However, negatively charged lysophospholipid micelles induce a higher content of alpha-helical structure than equivalent negatively charged diacylphospholipids in bilayers, reaching 100% of the alpha-helix content of cytochrome c in solution. Furthermore, micelles of lysolipids with the same zwitterionic headgroup of phospholipid bilayer vesicles induce approximately 60% of the alpha-helix content of cytochrome c in solution. On the basis of these results, we propose a mechanism for the folding of apocytochrome c induced by the interaction with lipid, which accounts for both electrostatic and hydrophobic contributions. Electrostatic lipid-protein interactions appear to direct the polypeptide to the micelle or vesicle surface and to induce an early partially folded state on the membrane surface. Hydrophobic interactions between nonpolar residues in the protein and the hydrophobic core of the lipid bilayer stabilize and extend the secondary structure upon membrane insertion.

Topics: Animals; Apoproteins; Circular Dichroism; Cytochrome c Group; Cytochromes c; Horses; Phosphatidylglycerols; Phospholipids; Protein Folding; Protein Structure, Secondary; Spectrometry, Fluorescence; Static Electricity; Tryptophan