Publications by authors named "Jancura D"

In aerobic organisms, cellular respiration is associated with electron transfer through a respiratory system of membrane-bound complexes. This electron flow is terminated by the reduction of dioxygen to water by respiratory oxidases. Cytochrome c oxidase (CcO) is a widely distributed heme-copper-oxygen reductase (HCO) found in all mitochondria and some bacteria.

View Article and Find Full Text PDF

Reoxidized cytochrome c oxidase appears to be in a 'high-energy' metastable state (O) in which part of the energy released in the redox reactions is stored. The O is supposed to relax to the resting 'as purified' oxidized state (O) in a time exceeding 200 ms. The catalytic heme a-Cu center of these two forms should differ in a protonation and ligation state and the transition of O-to-O is suggested to be associated with a proton transfer into this center.

View Article and Find Full Text PDF

Photobiomodulation (PBM) therapy is a relatively new modality for the combined treatment of cancer. Pre-treatment of certain types of cancer cells with PBM potentiates the treatment efficacy of photodynamic therapy (PDT). The mechanism of action of this synergetic effect is not yet fully understood.

View Article and Find Full Text PDF

Thermal denaturation of human serum albumin has been the subject of many studies in recent decades, but the results of these studies are often conflicting and inconclusive. To clarify this, we combined different spectroscopic and calorimetric techniques and performed an in-depth analysis of the structural changes that occur during the thermal unfolding of different conformational forms of human serum albumin. Our results showed that the inconsistency of the results in the literature is related to the different quality of samples in different batches, methodological approaches and experimental conditions used in the studies.

View Article and Find Full Text PDF

Due to the simple one-step preparation method and a promising application in biomedical research, amphiphilic gradient copoly(2-oxazoline)s are gaining more and more interest compared to their analogous block copolymers. In this work, the curcumin solubilization ability was tested for a series of amphiphilic gradient copoly(2-oxazoline)s with different lengths of hydrophobic side-chains, consisting of 2-ethyl-2-oxazoline as a hydrophilic monomer and 2-(4-alkyloxyphenyl)-2-oxazoline as a hydrophobic monomer. It is shown that the length of the hydrophobic side-chain in the copolymers plays a crucial role in the loading of curcumin onto the self-assembled nanoparticles.

View Article and Find Full Text PDF

The reduction of O in respiratory cytochrome oxidases (CcO) is associated with the generation of the transmembrane proton gradient by two mechanisms. In one of them, the proton pumping, two different types of the ferryl intermediates of the catalytic heme -Cu center and forms, participate. Equivalent ferryl states can be also formed by the reaction of the oxidized CcO () with HO.

View Article and Find Full Text PDF

Self-assembled nanostructures of amphiphilic gradient copoly(2-oxazoline)s have recently attracted attention as promising delivery systems for the effective delivery of hydrophobic anticancer drugs. In this study, we have investigated the effects of increasing hydrophobic side chain length on the self-assembly of gradient copolymers composed of 2-ethyl-2-oxazoline as the hydrophilic comonomer and various 2-(4-alkyloxyphenyl)-2-oxazolines as hydrophobic comonomers. We show that the size of the formed polymeric nanoparticles depends on the structure of the copolymers.

View Article and Find Full Text PDF

During catalysis of cytochrome c oxidases (CcO) several ferryl intermediates of the catalytic heme a-Cu center are observed. In the P ferryl state, produced by the reaction of two-electron reduced CcO with O, the ferryl iron of heme a and a free radical are present at the catalytic center. The radical reduction stimulates the transition of the P into another ferryl F state.

View Article and Find Full Text PDF

Several ferryl states of the catalytic heme a-Cu center of the respiratory cytochrome c oxidases (CcOs) are observed during the reduction of O2 to H2O. One of the P-type ferryl forms, P, is produced by the reaction of the two-electron reduced CcO with O2. In this state, the heme a iron is in the ferryl state and a free radical should be also present at the catalytic center.

View Article and Find Full Text PDF

Cytochrome a was suggested as the key redox center in the proton pumping process of bovine cytochrome c oxidase (CcO). Recent studies showed that both the structure of heme a and its immediate vicinity are sensitive to the ligation and the redox state of the distant catalytic center composed of iron of cytochrome a (Fe) and copper (Cu). Here, the influence of the ligation at the oxidized Fe-Cu center on the electron-proton coupling at heme a was examined in the wide pH range (6.

View Article and Find Full Text PDF

Flavin mononucleotide (FMN) belongs to the group of very efficient endogenous photosensitizers producing singlet oxygen, O, but with limited ability to be targeted. On the other hand, in genetically-encoded photosensitizers, which can be targeted by means of various tags, the efficiency of FMN to produce O is significantly diminished due to its interactions with surrounding amino acid residues. Recently, an increase of O production yield by FMN buried in a protein matrix was achieved by a decrease of quenching of the cofactor excited states by weakening of the protein-FMN interactions while still forming a complex.

View Article and Find Full Text PDF

LOV2 (Light-Oxygen-Voltage) domain from Avena sativa phototropin 1 (AsLOV2) belongs to the superfamily of PAS (Per-Arnt-Sim) domains, members of which function as signaling sensors. AsLOV2 undergoes a conformational change upon blue-light absorption by its FMN cofactor. AsLOV2 wild type (wt) is intensively studied as a photo-switchable element in conjugation with various proteins.

View Article and Find Full Text PDF

Low-density lipoproteins (LDL) and high-density lipoproteins (HDL) are natural occurring vehicles attractive for drug delivery and targeting tumor cells. Here we have investigated the encapsulation and interaction of a well-known anticancer agent curcumin with LDL and HDL. LDL particles have been found to accumulate more curcumin molecules inside their structure than HDL.

View Article and Find Full Text PDF

Background: Low-density lipoproteins (LDL) were used as a natural drug delivery system for the transport of hypericin (Hyp) in the bloodstream of the chicken's chorioallantoic membrane model (CAM). Hyp was chosen as a model for hydrophobic drug used in photo-diagnosis and photo-treatments (PDT). The extravasation of the Hyp:LDL complexes for different concentration ratios and the redistribution of Hyp between different serum components were investigated with an innovative statistical treatment.

View Article and Find Full Text PDF

Second-derivative absorption spectroscopy was employed to monitor the response of effective symmetry of cytochromes a and a to the redox and ligation states of bovine cytochrome c oxidase (CcO). The Soret band π → π* electronic transitions were used to display the changes in symmetry of these chromophores induced by the reduction of CcO inhibited by the exogenous ligands and during catalytic turnover. The second derivative of the difference absorption spectra revealed only a single Soret band for the oxidized cytochromes a and a and cyanide-ligated oxidized cytochrome a.

View Article and Find Full Text PDF

The singlet oxygen produced by energy transfer between an excited photosensitizer (pts) and ground-state oxygen molecules plays a key role in photodynamic therapy. Different nanocarrier systems are extensively studied to promote targeted pts delivery in a host body. The phosphorescence kinetics of the singlet oxygen produced by the short laser pulse photosensitization of pts inside nanoparticles is influenced by singlet oxygen diffusion from the particles to the surrounding medium.

View Article and Find Full Text PDF

The phosphorescence kinetics of singlet oxygen produced by photosensitized hypericin (Hyp) molecules inside low-density lipoprotein (LDL) particles was studied experimentally and by means of numerical and analytical modeling. The phosphorescence signal was measured after short laser pulse irradiation of aqueous Hyp/LDL solutions. The Hyp triplet state lifetime determined by a laser flash-photolysis measurement was 5.

View Article and Find Full Text PDF
Article Synopsis
  • A new gradient copolymer was created through a specific polymerization process, combining hydrophilic and lipophilic components to form nanoparticles in water.
  • The nanoparticles can effectively carry the anticancer drug curcumin, stabilizing it and enhancing its solubility in water.
  • In tests, these curcumin-loaded nanoparticles demonstrated strong stability, low toxicity, and effective uptake by cancer cell lines, suggesting a promising future for their use in drug delivery systems.
View Article and Find Full Text PDF

Hypericin (Hyp) is a hydrophobic pigment found in plants of the genus Hypericum which exhibits low levels of solubility in water. This work shows that the solubility of Hyp can be significantly increased through the addition of cromolyn disodium salt (DSCG). Performed studies using UV-VIS absorption and fluorescence spectroscopies demonstrate that Hyp remains in a predominantly biologically photodynamic active monomeric form in the presence of DSCG at concentrations ranging from 4.

View Article and Find Full Text PDF

The interaction between a ruthenium - based water soluble oxygen probe ([Ru(Phen)], phen - phenanthroline) and human serum albumin (HSA) was investigated with the aim of describing the influence of HSA on the [Ru(Phen)] luminescence properties. Nowadays, several oxygen sensitive luminescent probes are used to determine the oxygen level in different compartments of living organisms. However, they can interact, depending on their hydrophilic/hydrophobic characters, with various serum proteins, and/or lipids, during their utilization for invivo oxygen measurement.

View Article and Find Full Text PDF

Monitoring the fluorescence of proteins, particularly the fluorescence of intrinsic tryptophan residues, is a popular method often used in the analysis of unfolding transitions (induced by temperature, chemical denaturant, and pH) in proteins. The tryptophan fluorescence provides several suitable parameters, such as steady-state fluorescence intensity, apparent quantum yield, mean fluorescence lifetime, position of emission maximum that are often utilized for the observation of the conformational/unfolding transitions of proteins. In addition, the fluorescence intensities ratio at different wavelengths (usually at 330 nm and 350 nm) is becoming an increasingly popular parameter for the evaluation of thermal transitions.

View Article and Find Full Text PDF

The incorporation of hypericin (Hyp) from aqueous solutions into giant unilamellar vesicle (GUV) membranes has been studied experimentally and by means of kinetic Monte Carlo modeling. The time evolution of Hyp fluorescence originating from Hyp monomers dissolved in the GUV membrane has been recorded by confocal microscopy and while trapping individual GUVs in optical tweezers. It was shown that after reaching a maximum, the fluorescence intensity gradually decreased toward longer times.

View Article and Find Full Text PDF

ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) is a compound extensively employed to evaluate the free radical trapping capacity of antioxidant agents and complex mixtures such as biological fluids or foods. This evaluation is usually performed by using a colourimetric experiment, where preformed ABTS radical cation (ABTS˙) molecules are reduced in the presence of an antioxidant causing an intensity decrease of the specific ABTS˙ UV-visible absorption bands. In this work we report a strong effect of silver plasmonic nanoparticles (Ag NPs) on ABTS leading to the formation of ABTS˙.

View Article and Find Full Text PDF
Article Synopsis
  • This study examines how ethanol, pH levels, and silver nanoparticles (Ag NPs) affect the aggregation of the anticancer compound parietin in water and on metal surfaces.
  • Researchers utilized UV-visible absorption, fluorescence, and Raman spectroscopy to analyze the behavior of parietin in different environments, highlighting its deprotonation and molecular aggregation.
  • The study also explored how varying ethanol concentrations influence parietin's optical properties and characterized its interactions with Ag NPs using surface-enhanced optical techniques to determine ionization states and pKa values.
View Article and Find Full Text PDF

A PHP Error was encountered

Severity: Warning

Message: fopen(/var/lib/php/sessions/ci_sessionuud8gn6t4amrg8fckfs0h6vgilrvc9mi): Failed to open stream: No space left on device

Filename: drivers/Session_files_driver.php

Line Number: 177

Backtrace:

File: /var/www/html/index.php
Line: 316
Function: require_once

A PHP Error was encountered

Severity: Warning

Message: session_start(): Failed to read session data: user (path: /var/lib/php/sessions)

Filename: Session/Session.php

Line Number: 137

Backtrace:

File: /var/www/html/index.php
Line: 316
Function: require_once