Complexation of pyrene and anthracene with human blood plasma

Abstract

We have studied the interaction between polycyclic aromatic hydrocarbons (pyrene and anthracene) with human serum albumin (HSA) and human blood plasma. We have shown that the increase in the fluorescence intensity and the decrease in the polarity index of pyrene on going from an aqueous solution to a pH 7.4 buffer solution of HSA suggests that polycyclic aromatic hydrocarbons are localized in the hydrophobic microphase of the proteins. The increase in the fluorescence intensity for anthracene and pyrene, and also the decrease in the polarity index of pyrene on going from HSA to blood plasma is connected with the fact that polycyclic aromatic hydrocarbons can bind both to plasma proteins and to plasma lipids. When sodium dodecyl sulfate (SDS) is added to the blood plasma in a concentration greater than the critical micelle concentration, we observe an increase in the fluorescence intensity and the polarity index of pyrene. We hypothesize that this is connected with localization of pyrene near the interface between the hydrophobic and hydrophilic phases of the protein-SDS system. We have established that SDS leads to a change in the structure of blood plasma proteins and promotes escape of polycyclic aromatic hydrocarbons from the protein globules.Key words: human blood plasma, human serum albumin, polycyclic aromatic hydrocarbons, sodium dodecyl sulfate, fluorescence.Introduction. Luminescent probes are widely used in studying structural changes in proteins, lipoproteins, and also in studying the properties of biological membranes [1,2]. The properties of nonpolar microregions in microheterogeneous media have been studied using luminescent probes: polycyclic aromatic hydrocarbons, which due to hydrophobic interactions tend to escape from the polar aqueous medium or macrophase of the solution into the nonpolar microphase, i.e., into the interior volume of the surfactant micelles, which is followed from the changes in the vibrational structure of the fluorescence spectra of the probes [3]. The use of the fluorescence of pyrene, which belongs to the class of polycyclic aromatic hydrocarbons, is well known [4-6] for determination of changes in the physicochemical properties of biological systems and model lipid membranes. Analysis of the changes in the vibrational structure of the fluorescence spectra of pyrene [3-5] also makes it possible to obtain information about the polarity of the microenvironment of the luminescent probe when its position changes in different microheterogeneous media. In [6], using data from analysis of the vibronic structure of the monomer luminescence spectrum of pyrene in a model membrane of phosphatidylcholine liposomes, it was hypothesized that the pyrene molecules can not only move laterally along the surface of the membrane, but also can undergo transmembrane motion. Thus the use of a method based on analysis of changes in the vibronic structure of the fluorescence spectra of pyrene molecules is promising for studying processes connected with a change in where polycyclic aromatic hydroca...

Interglobular Diffusion of an Energy Donor in Triplet-Triplet Energy Transfer in Proteins

“…Since the anthracene is not soluble in water, the obtained results indicate that the HSA binds anthracene that is also confirmed by the results of [24].…”

Interaction of 1-pyrene sulfonic acid sodium salt with human serum albumin

“…Pyrene probes have strong absorption bands in the UV region, a high fluorescence quantum yield and long life time of the excited singlet state (can be examined with a nanosecond flash photolysis system). However, the literature concerning binding of pyrene and its derivatives to HSA or other serum albumins is not extensive [13,[19][20][21][22][23][24][25]. The albumin-induced changes of absorption and fluorescence spectra have been reported, but in most cases the authors do not specify unambiguously the probe/protein binding sites.…”

“…The albumin-induced changes of absorption and fluorescence spectra have been reported, but in most cases the authors do not specify unambiguously the probe/protein binding sites. Pyrene itself, as a neutral molecule, binds to HSA with a relatively low affinity (binding constant of the order of 10 4 M -1 ), and its polarity index (I 1 /I 3 ratio of vibronic peaks in the fluorescence spectrum) is close to that in ethanol or in aqueous micellar solution of sodium dodecyl sulfate [22,23].…”

Micelles Embedded in Multiphasic Protein Hydrogel Enable Efficient and Air-Tolerant Triplet Fusion Upconversion with Heavy-Atom and Spin–Orbit Charge-Transfer Sensitizers

“…The absorption and steady-state fluorescence spectra of DPA, Pery, and 1 – 6 within the individual BSA/SDS/hydrogel, SDS micelle, THF, and BSA environments are collected in Figure S3. The binding of the upconverters to BSA was characterized by a severe bathochromic shift in the absorbance, which represented a change in the substrate’s environment from the solvent to a binding site of BSA. , …”