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Miklós Poór – One of the best experts on this subject based on the ideXlab platform.

  • Interactions of zearalanone, α-zearalanol, β-zearalanol, zearalenone-14-sulfate, and zearalenone-14-glucoside with serum Albumin
    Mycotoxin Research, 2020
    Co-Authors: Zelma Faisal, Beáta Lemli, Sándor Kunsági-máté, Virág Vörös, Eszter Fliszár-nyúl, Miklós Poór
    Abstract:

    The xenoestrogenic mycotoxin zearalenone is a Fusarium -derived food and feed contaminant. In mammals, the reduced (e.g., zearalanone, α-zearalanol, and β-zearalanol) and conjugated (e.g., zearalenone-14-sulfate) metabolites of zearalenone are formed. Furthermore, filamentous fungi and plants are also able to convert zearalenone to conjugated derivatives, including zearalenone-14-sulfate and zearalenone-14-glucoside, respectively. Serum Albumin is the dominant plasma protein in the circulation; it interacts with certain mycotoxins, affecting their toxicokinetics. In a previous investigation, we demonstrated the remarkable species differences regarding the Albumin binding of zearalenone and zearalenols. In the current study, the interactions of zearalanone, α-zearalanol, β-zearalanol, zearalenone-14-sulfate, and zearalenone-14-glucoside with human, bovine, porcine, and rat serum Albumins were examined, employing fluorescence spectroscopy and affinity chromatography. Zearalanone, zearalanols, and zearalenone-14-sulfate form stable complexes with Albumins tested ( K = 9.3 × 10^3 to 8.5 × 10^5 L/mol), while the Albumin binding of zearalenone-14-glucoside seems to be weak. Zearalenone-14-sulfate formed the most stable complexes with Albumins examined. Considerable species differences were observed in the Albumin binding of zearalenone metabolites, which may have a role in the interspecies differences regarding the toxicity of zearalenone.

  • Interactions of zearalenone and its reduced metabolites α-zearalenol and β-zearalenol with serum Albumins: species differences, binding sites, and thermodynamics
    Mycotoxin Research, 2018
    Co-Authors: Zelma Faisal, Beáta Lemli, Sándor Kunsági-máté, Dénes Szerencsés, Mónika Bálint, Csaba Hetényi, Mónika Kuzma, Mátyás Mayer, Miklós Poór
    Abstract:

    Zearalenone (ZEN) is a mycotoxin produced by Fusarium species. ZEN mainly appears in cereals and related foodstuffs, causing reproductive disorders in animals, due to its xenoestrogenic effects. The main reduced metabolites of ZEN are α-zearalenol (α-ZEL) and β-zearalenol (β-ZEL). Similarly to ZEN, ZELs can also activate estrogen receptors; moreover, α-ZEL is the most potent endocrine disruptor among these three compounds. Serum Albumin is the most abundant plasma protein in the circulation; it affects the tissue distribution and elimination of several drugs and xenobiotics. Although ZEN binds to Albumin with high affinity, Albumin-binding of α-ZEL and β-ZEL has not been investigated. In this study, the complex formation of ZEN, α-ZEL, and β-ZEL with human (HSA), bovine (BSA), porcine (PSA), and rat serum Albumins (RSA) was investigated by fluorescence spectroscopy, affinity chromatography, thermodynamic studies, and molecular modeling. Our main observations are as follows: (1) ZEN binds with higher affinity to Albumins than α-ZEL and β-ZEL. (2) The low binding affinity of β-ZEL toward Albumin may result from its different binding position or binding site. (3) The binding constants of the mycotoxin-Albumin complexes significantly vary with the species. (4) From the thermodynamic point of view, the formation of ZEN-HSA and ZEN-RSA complexes are similar, while the formation of ZEN-BSA and ZEN-PSA complexes are markedly different. These results suggest that the toxicological relevance of ZEN-Albumin and ZEL-Albumin interactions may also be species-dependent.

  • Fluorescence spectroscopic evaluation of the interactions of quercetin, isorhamnetin, and quercetin-3′-sulfate with different Albumins
    Journal of Luminescence, 2018
    Co-Authors: Miklós Poór, Gabriella Boda, Sándor Kunsági-máté, Paul W. Needs, Paul A. Kroon, Beáta Lemli
    Abstract:

    Abstract Quercetin is one of the most commonly occurring flavonoids in nature. Although, quercetin and its metabolites express negligible fluorescence, the Albumin-bound form of quercetin has a strong fluorescence property. Considering the structural variance of different Albumins, we hypothesized that the fluorescence of Albumin complexes of quercetin and its metabolites may vary significantly. Therefore, in this study the fluorescence enhancement of quercetin and some of its major metabolites in the presence of bovine (BSA), human (HSA), porcine (PSA), and rat serum Albumins (RSA) were investigated by steady-state fluorescence spectroscopy in PBS buffer (pH 7.4). Among the tested quercetin metabolites, significant fluorescence signal was shown by Albumin complexes of quercetin, isorhamnetin, and quercetin-3′-sulfate, while other metabolites (tamarixetin, quercetin-3-glucuronide, and isorhamnetin-3-glucuronide) expressed negligible fluorescence. BSA was the most potent enhancer of quercetin-3′-sulfate but it showed poor effects regarding other flavonoids. The strongest enhancement of isorhamnetin was caused by HSA, while it was less effective enhancer of quercetin and quercetin-3′-sulfate. PSA showed a strong fluorescence enhancement of quercetin and quercetin-3′-sulfate but it was poorly effective regarding isorhamnetin. RSA was the most potent enhancer of quercetin but it caused only a weak enhancement of isorhamnetin and quercetin-3′-sulfate. Large changes of the pH (such as pH 5.0 and pH 10.0) almost completely abolished the fluorescence signals of the complexes. Nevertheless, slight decrease (pH 7.0) reduced and slight increase (pH 7.8) generally enhanced the fluorescence of flavonoid-Albumin complexes (only exceptions were quercetin-PSA and quercetin-RSA). Complex formations were also investigated by fluorescence quenching studies. Based on our results, the formations of quercetin-BSA, quercetin-HSA, isorhamnetin-BSA, isorhamnetin-HSA, isorhamnetin-PSA, and quercetin-3′-sulfate – HSA complexes followed 1:1 stoichiometry, while the presence of a secondary binding site of flavonoids was assumed regarding other tested Albumin complexes. Our study highlights that Albumins can induce significantly different fluorescence enhancement of flavonoids, and even the stoichiometry of flavonoid-Albumin complexes may differ.

Beáta Lemli – One of the best experts on this subject based on the ideXlab platform.

  • Interactions of zearalanone, α-zearalanol, β-zearalanol, zearalenone-14-sulfate, and zearalenone-14-glucoside with serum Albumin
    Mycotoxin Research, 2020
    Co-Authors: Zelma Faisal, Beáta Lemli, Sándor Kunsági-máté, Virág Vörös, Eszter Fliszár-nyúl, Miklós Poór
    Abstract:

    The xenoestrogenic mycotoxin zearalenone is a Fusarium -derived food and feed contaminant. In mammals, the reduced (e.g., zearalanone, α-zearalanol, and β-zearalanol) and conjugated (e.g., zearalenone-14-sulfate) metabolites of zearalenone are formed. Furthermore, filamentous fungi and plants are also able to convert zearalenone to conjugated derivatives, including zearalenone-14-sulfate and zearalenone-14-glucoside, respectively. Serum Albumin is the dominant plasma protein in the circulation; it interacts with certain mycotoxins, affecting their toxicokinetics. In a previous investigation, we demonstrated the remarkable species differences regarding the Albumin binding of zearalenone and zearalenols. In the current study, the interactions of zearalanone, α-zearalanol, β-zearalanol, zearalenone-14-sulfate, and zearalenone-14-glucoside with human, bovine, porcine, and rat serum Albumins were examined, employing fluorescence spectroscopy and affinity chromatography. Zearalanone, zearalanols, and zearalenone-14-sulfate form stable complexes with Albumins tested ( K = 9.3 × 10^3 to 8.5 × 10^5 L/mol), while the Albumin binding of zearalenone-14-glucoside seems to be weak. Zearalenone-14-sulfate formed the most stable complexes with Albumins examined. Considerable species differences were observed in the Albumin binding of zearalenone metabolites, which may have a role in the interspecies differences regarding the toxicity of zearalenone.

  • Interactions of zearalenone and its reduced metabolites α-zearalenol and β-zearalenol with serum Albumins: species differences, binding sites, and thermodynamics
    Mycotoxin Research, 2018
    Co-Authors: Zelma Faisal, Beáta Lemli, Sándor Kunsági-máté, Dénes Szerencsés, Mónika Bálint, Csaba Hetényi, Mónika Kuzma, Mátyás Mayer, Miklós Poór
    Abstract:

    Zearalenone (ZEN) is a mycotoxin produced by Fusarium species. ZEN mainly appears in cereals and related foodstuffs, causing reproductive disorders in animals, due to its xenoestrogenic effects. The main reduced metabolites of ZEN are α-zearalenol (α-ZEL) and β-zearalenol (β-ZEL). Similarly to ZEN, ZELs can also activate estrogen receptors; moreover, α-ZEL is the most potent endocrine disruptor among these three compounds. Serum Albumin is the most abundant plasma protein in the circulation; it affects the tissue distribution and elimination of several drugs and xenobiotics. Although ZEN binds to Albumin with high affinity, Albumin-binding of α-ZEL and β-ZEL has not been investigated. In this study, the complex formation of ZEN, α-ZEL, and β-ZEL with human (HSA), bovine (BSA), porcine (PSA), and rat serum Albumins (RSA) was investigated by fluorescence spectroscopy, affinity chromatography, thermodynamic studies, and molecular modeling. Our main observations are as follows: (1) ZEN binds with higher affinity to Albumins than α-ZEL and β-ZEL. (2) The low binding affinity of β-ZEL toward Albumin may result from its different binding position or binding site. (3) The binding constants of the mycotoxin-Albumin complexes significantly vary with the species. (4) From the thermodynamic point of view, the formation of ZEN-HSA and ZEN-RSA complexes are similar, while the formation of ZEN-BSA and ZEN-PSA complexes are markedly different. These results suggest that the toxicological relevance of ZEN-Albumin and ZEL-Albumin interactions may also be species-dependent.

  • Fluorescence spectroscopic evaluation of the interactions of quercetin, isorhamnetin, and quercetin-3′-sulfate with different Albumins
    Journal of Luminescence, 2018
    Co-Authors: Miklós Poór, Gabriella Boda, Sándor Kunsági-máté, Paul W. Needs, Paul A. Kroon, Beáta Lemli
    Abstract:

    Abstract Quercetin is one of the most commonly occurring flavonoids in nature. Although, quercetin and its metabolites express negligible fluorescence, the Albumin-bound form of quercetin has a strong fluorescence property. Considering the structural variance of different Albumins, we hypothesized that the fluorescence of Albumin complexes of quercetin and its metabolites may vary significantly. Therefore, in this study the fluorescence enhancement of quercetin and some of its major metabolites in the presence of bovine (BSA), human (HSA), porcine (PSA), and rat serum Albumins (RSA) were investigated by steady-state fluorescence spectroscopy in PBS buffer (pH 7.4). Among the tested quercetin metabolites, significant fluorescence signal was shown by Albumin complexes of quercetin, isorhamnetin, and quercetin-3′-sulfate, while other metabolites (tamarixetin, quercetin-3-glucuronide, and isorhamnetin-3-glucuronide) expressed negligible fluorescence. BSA was the most potent enhancer of quercetin-3′-sulfate but it showed poor effects regarding other flavonoids. The strongest enhancement of isorhamnetin was caused by HSA, while it was less effective enhancer of quercetin and quercetin-3′-sulfate. PSA showed a strong fluorescence enhancement of quercetin and quercetin-3′-sulfate but it was poorly effective regarding isorhamnetin. RSA was the most potent enhancer of quercetin but it caused only a weak enhancement of isorhamnetin and quercetin-3′-sulfate. Large changes of the pH (such as pH 5.0 and pH 10.0) almost completely abolished the fluorescence signals of the complexes. Nevertheless, slight decrease (pH 7.0) reduced and slight increase (pH 7.8) generally enhanced the fluorescence of flavonoid-Albumin complexes (only exceptions were quercetin-PSA and quercetin-RSA). Complex formations were also investigated by fluorescence quenching studies. Based on our results, the formations of quercetin-BSA, quercetin-HSA, isorhamnetin-BSA, isorhamnetin-HSA, isorhamnetin-PSA, and quercetin-3′-sulfate – HSA complexes followed 1:1 stoichiometry, while the presence of a secondary binding site of flavonoids was assumed regarding other tested Albumin complexes. Our study highlights that Albumins can induce significantly different fluorescence enhancement of flavonoids, and even the stoichiometry of flavonoid-Albumin complexes may differ.

Masaki Otagiri – One of the best experts on this subject based on the ideXlab platform.

  • Further Evidence Regarding the Important Role of Chlorine Atoms of Aripiprazole on Binding to the Site II Area of Human Albumin
    Journal of pharmaceutical sciences, 2018
    Co-Authors: Keiki Sakurama, Masaki Otagiri, Kazuaki Taguchi, Koji Nishi, Shuhei Imoto, Mai Hashimoto, Teruyuki Komatsu, Yoshitsugu Morita, Keishi Yamasaki
    Abstract:

    Previously, we reported on the high-affinity binding of aripiprazole (ARP), an antipsychotic drug, to human Albumin and the role of the chlorine atom of ARP on this binding. In this study, we investigated the binding mode of ARP to human Albumin in detail using ARP derivatives and several animal-derived Albumins. ARP bound strongly to human and dog Albumin. The circular dichdichroism (CD) spectra of ARP bound to human and dog Albumin were also similar. Deschloro-ARP bound less strongly to all of the Albumin species compared to ARP, and the shapes of CD spectra were similar for all Albumin species. CD spectra of dimethyl-ARP, for which chlorine atoms were substituted methyl groups, were quite similar to that of deschloro-ARP. In displacement experiments, competitive binding was observed between ARP and deschloro-ARP. These results suggest that the chlorine atoms in ARP are involved in the binding modes of ARP for human and dog Albumins, whereas ARP and deschloro-ARP appear to share the same binding region in site II. The aforementioned results imply that compounds having a chlorine atom bind more strongly to plasma proteins, resulting in a long blood retention time. Therefore, findings reported here may provide the basically useful data for drug design.

  • species differences in the binding of sodium 4 phenylbutyrate to serum Albumin
    Journal of Pharmaceutical Sciences, 2017
    Co-Authors: Keishi Yamasaki, Toru Maruyama, Taisuke Enokida, Kazuaki Taguchi, Shigeyuki Miyamura, Akito Kawai, Shuichi Miyamoto, Masaki Otagiri
    Abstract:

    Sodium 4-phenylbutyrate (PB) is clinically used as a drug for treating urea cycle disorders. Recent research has shown that PB also has other pharmacologic activities, suggesting that it has the potential for use as a drug for treating other disorders. In the process of drug development, preclinical testing using experimental animals is necessary to verify the efficacy and safety of PB. Although the binding of PB to human Albumin has been studied, our knowledge of its binding to Albumin from the other animal species is extremely limited. To address this issue, we characterized the binding of PB to Albumin from several species (human, bovine, rabbit, and rat). The results indicated that PB interacts with 1 high-affinity site of Albumin from these species, which corresponds to site II of human Albumin. The affinities of PB to human and bovine Albumins were higher than those to rabbit and rat Albumin, and that to rabbit Albumin was the lowest. Binding and molecular docking studies using structurally related compounds of PB suggested that species differences in the affinity are attributed to differences in the structural feature of the PB-binding sites on Albumins (e.g., charge distribution, hydrophobicity, shape, or size).

  • Species Differences of Serum Albumins: I. Drug Binding Sites
    Pharmaceutical Research, 1997
    Co-Authors: Takamitsu Kosa, Toru Maruyama, Masaki Otagiri
    Abstract:

    Purpose. The purpose of this study was the classification and identification of drug binding sites on Albumins from several species in order to understand species differences of both drug binding properties and drug interaction on protein binding. Methods. Binding properties and types of drug-drug interaction on the different Albumins were examined using typical site I binding drugs, warfarin (WF) and phenylbutazone (PBZ), and site II binding drugs, ibuprofen (IP) and diazepam (DZ) on human Albumin. Equilibrium dialysis was carried out for two drugs and the free concentrations of drugs were then treated using the methods of Kragh-Hansen (Mol. Pharmacol. 34. 160−171, (1988)). Results. Binding affinities of site I drugs to bovine, rabbit and rat Albumins were reasonably similar to human Albumin. However, interestingly, those to dog Albumin were considerably smaller than human Albumin. On the other hand, binding parameters of DZ to bovine, rabbit and rat Albumins were apparently different from those of human Albumin. These differences are best explained by microenvironmental changes in the binding sites resulting from change of size and/or hydrophobicity of the binding pocket, rather than a variation in amino acid residues. Conclusions. We will propose herein that mammalian serum Albumins used in this study contain specific drug binding sites: Rabbit and rat Albumins contain a drug binding site, corresponding to site I on human Albumin, and dog Albumin contains a specific drug binding site corresponding to site II on the human Albumin molecule.

Sándor Kunsági-máté – One of the best experts on this subject based on the ideXlab platform.

  • Interactions of zearalanone, α-zearalanol, β-zearalanol, zearalenone-14-sulfate, and zearalenone-14-glucoside with serum Albumin
    Mycotoxin Research, 2020
    Co-Authors: Zelma Faisal, Beáta Lemli, Sándor Kunsági-máté, Virág Vörös, Eszter Fliszár-nyúl, Miklós Poór
    Abstract:

    The xenoestrogenic mycotoxin zearalenone is a Fusarium -derived food and feed contaminant. In mammals, the reduced (e.g., zearalanone, α-zearalanol, and β-zearalanol) and conjugated (e.g., zearalenone-14-sulfate) metabolites of zearalenone are formed. Furthermore, filamentous fungi and plants are also able to convert zearalenone to conjugated derivatives, including zearalenone-14-sulfate and zearalenone-14-glucoside, respectively. Serum Albumin is the dominant plasma protein in the circulation; it interacts with certain mycotoxins, affecting their toxicokinetics. In a previous investigation, we demonstrated the remarkable species differences regarding the Albumin binding of zearalenone and zearalenols. In the current study, the interactions of zearalanone, α-zearalanol, β-zearalanol, zearalenone-14-sulfate, and zearalenone-14-glucoside with human, bovine, porcine, and rat serum Albumins were examined, employing fluorescence spectroscopy and affinity chromatography. Zearalanone, zearalanols, and zearalenone-14-sulfate form stable complexes with Albumins tested ( K = 9.3 × 10^3 to 8.5 × 10^5 L/mol), while the Albumin binding of zearalenone-14-glucoside seems to be weak. Zearalenone-14-sulfate formed the most stable complexes with Albumins examined. Considerable species differences were observed in the Albumin binding of zearalenone metabolites, which may have a role in the interspecies differences regarding the toxicity of zearalenone.

  • Interactions of zearalenone and its reduced metabolites α-zearalenol and β-zearalenol with serum Albumins: species differences, binding sites, and thermodynamics
    Mycotoxin Research, 2018
    Co-Authors: Zelma Faisal, Beáta Lemli, Sándor Kunsági-máté, Dénes Szerencsés, Mónika Bálint, Csaba Hetényi, Mónika Kuzma, Mátyás Mayer, Miklós Poór
    Abstract:

    Zearalenone (ZEN) is a mycotoxin produced by Fusarium species. ZEN mainly appears in cereals and related foodstuffs, causing reproductive disorders in animals, due to its xenoestrogenic effects. The main reduced metabolites of ZEN are α-zearalenol (α-ZEL) and β-zearalenol (β-ZEL). Similarly to ZEN, ZELs can also activate estrogen receptors; moreover, α-ZEL is the most potent endocrine disruptor among these three compounds. Serum Albumin is the most abundant plasma protein in the circulation; it affects the tissue distribution and elimination of several drugs and xenobiotics. Although ZEN binds to Albumin with high affinity, Albumin-binding of α-ZEL and β-ZEL has not been investigated. In this study, the complex formation of ZEN, α-ZEL, and β-ZEL with human (HSA), bovine (BSA), porcine (PSA), and rat serum Albumins (RSA) was investigated by fluorescence spectroscopy, affinity chromatography, thermodynamic studies, and molecular modeling. Our main observations are as follows: (1) ZEN binds with higher affinity to Albumins than α-ZEL and β-ZEL. (2) The low binding affinity of β-ZEL toward Albumin may result from its different binding position or binding site. (3) The binding constants of the mycotoxin-Albumin complexes significantly vary with the species. (4) From the thermodynamic point of view, the formation of ZEN-HSA and ZEN-RSA complexes are similar, while the formation of ZEN-BSA and ZEN-PSA complexes are markedly different. These results suggest that the toxicological relevance of ZEN-Albumin and ZEL-Albumin interactions may also be species-dependent.

  • Fluorescence spectroscopic evaluation of the interactions of quercetin, isorhamnetin, and quercetin-3′-sulfate with different Albumins
    Journal of Luminescence, 2018
    Co-Authors: Miklós Poór, Gabriella Boda, Sándor Kunsági-máté, Paul W. Needs, Paul A. Kroon, Beáta Lemli
    Abstract:

    Abstract Quercetin is one of the most commonly occurring flavonoids in nature. Although, quercetin and its metabolites express negligible fluorescence, the Albumin-bound form of quercetin has a strong fluorescence property. Considering the structural variance of different Albumins, we hypothesized that the fluorescence of Albumin complexes of quercetin and its metabolites may vary significantly. Therefore, in this study the fluorescence enhancement of quercetin and some of its major metabolites in the presence of bovine (BSA), human (HSA), porcine (PSA), and rat serum Albumins (RSA) were investigated by steady-state fluorescence spectroscopy in PBS buffer (pH 7.4). Among the tested quercetin metabolites, significant fluorescence signal was shown by Albumin complexes of quercetin, isorhamnetin, and quercetin-3′-sulfate, while other metabolites (tamarixetin, quercetin-3-glucuronide, and isorhamnetin-3-glucuronide) expressed negligible fluorescence. BSA was the most potent enhancer of quercetin-3′-sulfate but it showed poor effects regarding other flavonoids. The strongest enhancement of isorhamnetin was caused by HSA, while it was less effective enhancer of quercetin and quercetin-3′-sulfate. PSA showed a strong fluorescence enhancement of quercetin and quercetin-3′-sulfate but it was poorly effective regarding isorhamnetin. RSA was the most potent enhancer of quercetin but it caused only a weak enhancement of isorhamnetin and quercetin-3′-sulfate. Large changes of the pH (such as pH 5.0 and pH 10.0) almost completely abolished the fluorescence signals of the complexes. Nevertheless, slight decrease (pH 7.0) reduced and slight increase (pH 7.8) generally enhanced the fluorescence of flavonoid-Albumin complexes (only exceptions were quercetin-PSA and quercetin-RSA). Complex formations were also investigated by fluorescence quenching studies. Based on our results, the formations of quercetin-BSA, quercetin-HSA, isorhamnetin-BSA, isorhamnetin-HSA, isorhamnetin-PSA, and quercetin-3′-sulfate – HSA complexes followed 1:1 stoichiometry, while the presence of a secondary binding site of flavonoids was assumed regarding other tested Albumin complexes. Our study highlights that Albumins can induce significantly different fluorescence enhancement of flavonoids, and even the stoichiometry of flavonoid-Albumin complexes may differ.

Sonia R W Louro – One of the best experts on this subject based on the ideXlab platform.

  • methyl parathion interaction with human and bovine serum Albumin
    Toxicology Letters, 2004
    Co-Authors: Dilson Silva, Celia Martins Cortez, Jayme Cunhabastos, Sonia R W Louro
    Abstract:

    Abstract Methyl parathion (MP; O , O -dimethyl O – p -nitrophenyl phosphorothioate) is an organophosphorous compound still largely used in agriculture and fish hatcheries. This pesticide is not quite selective and is potentially toxic for both vertebrates and invertebrates. Its mechanism of acute toxicity is the inhibition of the enzyme acetylcholinesterase in nervous tissue. Binding of pesticides to plasma proteins is one of many factors that influence their distribution and elimination. The free concentration available for toxic action can be effectively reduced for pesticides with high binding to plasma proteins, although the affinity of pesticides to plasma proteins is often lower than for the enzyme targets. Several different transport proteins exist in blood plasma, but Albumin only is able to bind a wide diversity of xenobiotics reversibly with high affinity. It was already known that parathion (ethyl parathion) exhibits a high affinity to human and bovine serum Albumins. We studied interactions of methyl parathion with these Albumins by using fluorescence quenching techniques. We selectively excited the fluorescence of tryptophan residues with a 290 nm wavelength light, and observed quenching by titrating human and bovine serum Albumin solutions with methyl parathion. Stern–Volmer graphs were plotted and quenching constants were estimated. Our results pointed to the formation of complexes of methyl parathion with Albumins. Association constants at 25 °C were 3.07×10 4 (1.2×10 3 ) M −1 for human serum Albumin, and 1.96×10 4 (±4.5×10 2 ) M −1 for bovine serum Albumin. At 37 °C, they were 1.08×10 4 (±2.0×10 2 ) M −1 for human serum Albumin, and 8.16×10 3 (±1.9×10 2 ) M −1 for bovine serum Albumin. Results also suggest that the primary binding site for methyl parathion on Albumin is close to tryptophan residues 214 of human serum Albumin and 212 of bovine serum Albumin.

  • Methyl parathion interaction with human and bovine serum Albumin
    Toxicology Letters, 2004
    Co-Authors: Dilson Silva, Celia Martins Cortez, Jayme Cunha-bastos, Sonia R W Louro
    Abstract:

    Methyl parathion (MP; O,O-dimethyl O-p-nitrophenyl phosphorothioate) is an organophosphorous compound still largely used in agriculture and fish hatcheries. This pesticide is not quite selective and is potentially toxic for both vertebrates and invertebrates. Its mechanism of acute toxicity is the inhibition of the enzyme acetylcholinesterase in nervous tissue. Binding of pesticides to plasma proteins is one of many factors that influence their distribution and elimination. The free concentration available for toxic action can be effectively reduced for pesticides with high binding to plasma proteins, although the affinity of pesticides to plasma proteins is often lower than for the enzyme targets. Several different transport proteins exist in blood plasma, but Albumin only is able to bind a wide diversity of xenobiotics reversibly with high affinity. It was already known that parathion (ethyl parathion) exhibits a high affinity to human and bovine serum Albumins. We studied interactions of methyl parathion with these Albumins by using fluorescence quenching techniques. We selectively excited the fluorescence of tryptophan residues with a 290 nm wavelength light, and observed quenching by titrating human and bovine serum Albumin solutions with methyl parathion. Stern-Volmer graphs were plotted and quenching constants were estimated. Our results pointed to the formation of complexes of methyl parathion with Albumins. Association constants at 25 degrees C were 3.07 x 10(4) (1.2 x 10(3))M(-1) for human serum Albumin, and 1.96 x 10(4) (+/- 4.5 x 10(2))M(-1) for bovine serum Albumin. At 37 degrees C, they were 1.08 x 10(4) (+/- 2.0 x 10(2))M(-1) for human serum Albumin, and 8.16 x 10(3) (+/- 1.9 x 10(2))M(-1) for bovine serum Albumin. Results also suggest that the primary binding site for methyl parathion on Albumin is close to tryptophan residues 214 of human serum Albumin and 212 of bovine serum Albumin.