RESUMEN

The stability of ternary copper(II) complexes of a heterocyclic ligand, L (L being 2,2'-bipyridine (bipy) or 1,10-phenanthroline (phen)) and the fluorescent antibacterial agent norfloxacin (NFX) as the second ligand was studied at pH7.4 and different ionic strengths. Fluorescence quenching upon titration of NFX with the binary complexes allowed to obtain stability constants for NFX binding, Kb, as a function of ionic strength. The Kb values vary by more than two orders of magnitude when buffer concentration varies from 0.5 to 100mM. It was observed that previously synthesized ternary complexes dissociate in buffer according with the obtained stability constants. This shows that equimolar solutions of NFX and binary complexes are equivalent to solutions of synthesized ternary complexes. The interaction of the ternary copper complexes with anionic SDS (sodium dodecyl sulfate) micelles was studied by fluorescence and electron paramagnetic resonance (EPR). Titration of NFX-loaded SDS micelles with the complexes Cu:L allowed to determine the stability constants inside the micelles. Fluorescence quenching demonstrated that SDS micelles increase the stability constants by factors around 50. EPR spectra gave details of the copper(II) local environment, and demonstrated that the structure of the ternary complexes inside SDS micelles is different from that in buffer. Mononuclear ternary complexes formed inside the micelles, while in buffer most ternary complexes are binuclear. The results show that anionic membrane interfaces increase formation of copper fluoroquinolone complexes, which can influence bioavailability, membrane diffusion, and mechanism of action of the antibiotics.

Asunto(s)

Complejos de Coordinación/química , Cobre/química , Micelas , Norfloxacino/química , Dodecil Sulfato de Sodio/química , Espectroscopía de Resonancia por Spin del Electrón , Ligandos , Espectrometría de Fluorescencia

RESUMEN

Copper(II) complexes with the first-generation quinolone antibacterial agent norfloxacin containing a nitrogen donor heterocyclic ligand 2,2'-bipyridine (bipy) or 1,10-phenanthroline (phen) were prepared and characterized by IR, EPR spectra, molar conductivity, and elemental analyses. The experimental data suggest that norfloxacin was coordinated to copper(II) through the carboxylato and ketone oxygen atoms. The interaction of the copper(II) complexes with bovine serum albumin (BSA) and human serum albumin (HSA) was investigated using fluorescence quenching of the tryptophan residues and copper(II) EPR spectroscopy. The results of fluorescence titration revealed that copper(II) complexes have a moderate ability to quench the intrinsic fluorescence of the albumins through a static quenching mechanism. EPR experiments showed that BSA and HSA Cu(II) sites compete with NOR for Cu(II)-bipy and Cu(II)-phen to form protein mixed-ligand complexes. Copper(II) complexes, together with the corresponding ligands, were evaluated for their trypanocidal activity in vitro against Trypanosoma cruzi, the causative agent of Chagas disease. The tests performed using bloodstream trypomastigotes showed that the Cu(II)-N-donor precursors and the metal complexes were more active than the free fluoroquinolone.

RESUMEN

Copper(II) complexes [Cu(H2O)2 (L1)(phen)](ClO4) (1) and [Cu(H2O)(L2)(phen)](ClO4) (2) (HL1 = naringenin; HL2 = hesperetin) were obtained, in which an anionic flavonoid ligand is attached to the metal center along with 1,10-phenanthroline (phen) as co-ligand. Complexes (1) and (2) were assayed for their cytotoxic activity against A549 lung carcinoma and against normal lung fibroblasts (LL-24) and human umbilical vein endothelial cells (HUVEC). We found IC50 = 16.42 µM (1) and IC50 = 5.82 µM (2) against A549 tumor cells. Complexes (1) and (2) exhibited slight specificity, being more cytotoxic against malignant than against non-malignant cells. 1 and 2 induced apoptosis on A549 cells in a mitochondria-independent pathway, and showed antioxidant activity. The antioxidant effect of the complexes could possibly improve their apoptotic action, most likely by a PI3K-independent reduction of autophagy. Complexes (1) and (2) interact in vitro with calf thymus DNA by an intercalative binding mode. EPR data indicated that 1 and 2 interact with human serum albumin (HSA) forming mixed ligand species.

Asunto(s)

Adenocarcinoma/tratamiento farmacológico , Complejos de Coordinación/administración & dosificación , Cobre/administración & dosificación , Neoplasias Pulmonares/tratamiento farmacológico , Adenocarcinoma/química , Adenocarcinoma del Pulmón , Antineoplásicos/administración & dosificación , Antineoplásicos/química , Apoptosis/efectos de los fármacos , Línea Celular Tumoral , Complejos de Coordinación/química , Cobre/química , ADN/química , Fibroblastos/efectos de los fármacos , Flavanonas/administración & dosificación , Flavanonas/química , Hesperidina/administración & dosificación , Hesperidina/química , Células Endoteliales de la Vena Umbilical Humana/efectos de los fármacos , Humanos , Neoplasias Pulmonares/química

RESUMEN

Zn(II) complexes with norfloxacin (NOR) in the absence or in the presence of 1,10-phenanthroline (phen) were obtained and characterized. In both complexes, the ligand NOR was coordinated through a keto and a carboxyl oxygen. Tetrahedral and octahedral geometries were proposed for [ZnCl2(NOR)]·H2O (1) and [ZnCl2(NOR)(phen)]·2H2O (2), respectively. Since the biological activity of the chemicals depends on the pH value, pH titrations of the Zn(II) complexes were performed. UV spectroscopic studies of the interaction of the complexes with calf-thymus DNA (CT DNA) have suggested that they can bind to CT DNA with moderate affinity in an intercalative mode. The interactions between the Zn(II) complexes and bovine serum albumin (BSA) were investigated by steady-state and time-resolved fluorescence spectroscopy at pH 7.4. The experimental data showed static quenching of BSA fluorescence, indicating that both complexes bind to BSA. A modified Stern-Volmer plot for the quenching by complex 2 demonstrated preferential binding near one of the two tryptophan residues of BSA. The binding constants obtained (K b ) showed that BSA had a two orders of magnitude higher affinity for complex 2 than for 1. The results also showed that the affinity of both complexes for BSA was much higher than for DNA. This preferential interaction with protein sites could be important to their biological mechanisms of action. The analysis in vitro of the Zn(II) complexes and corresponding ligand were assayed against Trypanosoma cruzi, the causative agent of Chagas disease and the data showed that complex 2 was the most active against bloodstream trypomastigotes.

Asunto(s)

Antiprotozoarios/química , Antiprotozoarios/farmacología , ADN/química , Norfloxacino/química , Compuestos Organometálicos/farmacología , Albúmina Sérica Bovina/química , Trypanosoma cruzi/efectos de los fármacos , Zinc/química , Animales , Antiprotozoarios/síntesis química , Sitios de Unión/efectos de los fármacos , Bovinos , Relación Dosis-Respuesta a Droga , Fluorescencia , Concentración de Iones de Hidrógeno , Compuestos Organometálicos/síntesis química , Compuestos Organometálicos/química , Pruebas de Sensibilidad Parasitaria , Relación Estructura-Actividad

RESUMEN

[Cu(HL)Cl2] complexes of chalcone-derived thiosemicarbazones were obtained with 3-phenyl-1-pyridin-2-ylprop-2-en-1-one thiosemicarbazone (HPyCTPh), complex (1), 3-(4-chlorophenyl)-1-pyridin-2-ylprop-2-en-1-one thiosemicarbazone (HPyCT4ClPh), complex (2), 3-(4-bromophenyl)-1-pyridin-2-ylprop-2-en-1-one thiosemicarbazone (HPyCT4BrPh), complex (3), and 3-(4-nitrophenyl-1-pyridin-2-ylprop-2-en-1-one thiosemicarbazone (HPyCT4NO2Ph), complex (4). 1-3 showed interaction with bovine serum albumin (BSA) and deoxyribonucleic acid from calf thymus (CT-DNA). The cytotoxic activities of the thiosemicarbazones and complexes (1-4) were tested against HL60 (wild type human promyelocytic leukemia), Jurkat (human immortalized line of T lymphocyte), MDA-MB 231 (human breast carcinoma) and HCT-116 (human colorectal carcinoma) tumor cell lineages. Upon coordination to copper(II) cytotoxicity significantly increased in Jurkat, MDA-MB 231 and HCT-116 cells. Unlike the free thiosemicarbazones, 1-4 induced DNA fragmentation in solid tumor cells indicating their pro-apoptotic potential.

Asunto(s)

Antineoplásicos/farmacología , Chalcona/química , Cobre/química , ADN/efectos de los fármacos , Compuestos Organometálicos/farmacología , Albúmina Sérica Bovina/antagonistas & inhibidores , Tiosemicarbazonas/química , Animales , Antineoplásicos/síntesis química , Antineoplásicos/química , Apoptosis/efectos de los fármacos , Sitios de Unión/efectos de los fármacos , Bovinos , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , ADN/química , Relación Dosis-Respuesta a Droga , Ensayos de Selección de Medicamentos Antitumorales , Células HCT116 , Células HL-60 , Humanos , Células Jurkat , Modelos Moleculares , Estructura Molecular , Compuestos Organometálicos/síntesis química , Compuestos Organometálicos/química , Albúmina Sérica Bovina/química , Relación Estructura-Actividad

RESUMEN

Quinolones are known for their antimicrobial and antitumor activities. Gold(III) compounds constitute an emerging class of biologically active substances, of special interest as potential anticancer agents. In this work three gold(III) complexes of the fluoroquinolones antimicrobial agents norfloxacin (NOR), levofloxacin (LEVO) and sparfloxacin (SPAR) were prepared and characterized with physicochemical and spectroscopic techniques. In these complexes, NOR, LEVO and SPAR act as bidentate neutral ligands bound to gold(III) through the nitrogen atoms of the piperazine ring, which is an unusual mode of coordination for this class of compounds. Two chloride ions occupy the remaining coordination sites. The cytotoxic activity of the fluoroquinolones and their gold(III) complexes was tested against the A20 (murine lymphoma), B16-F10 (murine melanoma) and K562 (human myeloid leukemia) tumor cell lines as well as the L919 (murine lung fibroblasts) and MCR-5 (human lung fibroblasts) normal cells lines. All complexes were more active than their corresponding free ligands. Complex [AuCl(2)(LEVO)]Cl was selected for DNA fragmentation and cell cycle analysis. Spectroscopic titration with calf-thymus DNA (CT DNA) showed that the complexes can bind weakly to CT DNA, probably by an external contact (electrostatic or groove binding). The complexes exhibit good binding propensity to bovine serum albumin (BSA) having relatively high binding constant values.

Asunto(s)

ADN/metabolismo , Fluoroquinolonas/química , Compuestos Orgánicos de Oro/metabolismo , Compuestos Orgánicos de Oro/farmacología , Albúmina Sérica Bovina/metabolismo , Animales , Antineoplásicos/química , Antineoplásicos/metabolismo , Antineoplásicos/farmacología , Transporte Biológico , Bovinos , Ciclo Celular/efectos de los fármacos , Línea Celular Tumoral , Quelantes/química , Quelantes/metabolismo , Quelantes/farmacología , Fragmentación del ADN/efectos de los fármacos , Humanos , Concentración 50 Inhibidora , Ratones , Compuestos Orgánicos de Oro/química

RESUMEN

Copper(II) complexes of fluoroquinolone antibacterial agents levofloxacin (LEV) and sparfloxacin (SPAR), containing or not a nitrogen donor heterocyclic ligand, 2,2'-bipyridine (bipy) or 1,10-phenathroline (phen), were prepared and characterized. The complexes are of the type [CuCl(2)(H(2)O)(L)], [CuCl(bipy)(L)]Cl and [CuCl(2)(phen)(L)], where L = LEV or SPAR. The data suggest that LEV and SPAR act as zwitterionic bidentade ligands coordinated to Cu(II) through the carboxylate and ketone oxygen atoms. The electron paramagnetic resonance spectra of the [CuCl(bipy)(L)]Cl and [CuCl(2)(phen)(L)] complexes (L = LEV and SPAR) in aqueous and DMSO solutions indicate mixture of mononuclear and binuclear forms. The Cu(II) complexes, together with the corresponding ligands, were evaluated for their trypanocidal activity in vitro against Trypanosoma cruzi, the causative agent of Chagas disease. The assays performed against bloodstream trypomastigotes showed that all complexes were more active than their corresponding ligands. Complexes [CuCl(2)(phen)(LEV)] and [CuCl(2)(phen)(SPAR)] were revealed, among all studied compounds, to be the most active with IC(50) = 1.6 and 4.7 µM, respectively, both presenting a superior effect than benznidazole. The interactions of fluoroquinolones and their Cu(II) complexes with calf-thymus DNA were investigated. These compounds showed binding properties towards DNA, with moderated binding constants values, suggesting that this structure may represent a parasite target.

Asunto(s)

Cobre/farmacología , Fluoroquinolonas/farmacología , Compuestos Organometálicos/farmacología , Tripanocidas/farmacología , Trypanosoma cruzi/efectos de los fármacos , Animales , Bovinos , Cobre/metabolismo , ADN/efectos de los fármacos , ADN/metabolismo , Espectroscopía de Resonancia por Spin del Electrón , Fluoroquinolonas/química , Fluoroquinolonas/metabolismo , Técnicas In Vitro , Levofloxacino , Ofloxacino/química , Ofloxacino/metabolismo , Ofloxacino/farmacología , Compuestos Organometálicos/química , Compuestos Organometálicos/metabolismo , Espectrofotometría Ultravioleta , Tripanocidas/química , Tripanocidas/metabolismo

RESUMEN

Formation of gold(III) complexes with the synthetic antibiotic norfloxacin (NF) was investigated in aqueous solution at pH 4.0, 7.5 and 10.6, with the ligand in cationic, zwitterionic and anionic forms, respectively. UV-Visible spectroscopy, steady state and time-resolved fluorometry were used to characterize the complexes. Binding sites, association constants and fluorescence lifetimes of the complexes were obtained. Au(3+) binding to zwitterionic NF produced a fluorescence decrease and a small red shift. Fluorescence changes as a function of Au(3+) concentration were fitted using a one-site binding model and the association constant was obtained, K(bzw) = 1.7 X 105 M⁻¹. The association of Au(3+) with cationic NF was much weaker, the obtained binding constant being K(bcat) = 2.4 X 10³ M⁻¹. The Au(3+) binding site for these species involves the carboxyl group, in agreement with a much stronger association of the cation with the carboxylate anion than with the neutral acid. Association of Au(3+) with nonfluorescent anionic NF presented a clear evidence of two binding sites. The highest affinity site is the unprotonated piperazinyl group with K(bpip) ≥ 5 X 107 M⁻¹ , and the low affinity site includes the carboxylate anion. The results point out to important pH dependent differences in complex formation between transition metal ions and fluoroquinolones, leading to different binding sites and association constants that change by several orders of magnitude.

Asunto(s)

Antibacterianos/química , Fluorescencia , Oro/química , Norfloxacino/química , Compuestos Orgánicos de Oro/química , Concentración de Iones de Hidrógeno , Estructura Molecular , Soluciones , Espectrometría de Fluorescencia , Espectrofotometría Ultravioleta , Agua/química

RESUMEN

The copper(II) complexes [Cu(H2Am4DH)Cl2] (1), [Cu(H2Am4Me)Cl2] (2), [Cu(H2Am4Et)Cl2] (3) and [Cu(2Am4Ph)Cl] (4) with 2-pyridineformamide thiosemicarbazone (H2Am4DH) and its N(4)-methyl (H2Am4Me), N(4)-ethyl (H2Am4Et) and N(4)-phenyl (H2Am4Ph) derivatives were studied by means of infrared and EPR spectral techniques. The crystal structure of 4 was determined. The studied compounds proved to be toxic to Artemia salina, suggesting that they could present cytotoxic activity against solid tumors. Among the free thiosemicarbazones H2Am4Ph presented higher toxicity than all other compounds, which showed comparable effects. In the case of complexes 2 and 3 toxicity is probably attributable to the complex as an entity or to a synergistic effect involving the thiosemicarbazone and copper. H2Am4Ph and complexes 2 and 3 revealed to be the most promising compounds as potential antineoplasic agents.

Asunto(s)

Artemia/efectos de los fármacos , Cobre/química , Formamidas/química , Formamidas/toxicidad , Piridinas/química , Piridinas/toxicidad , Tiosemicarbazonas/química , Animales , Cristalografía por Rayos X , Espectroscopía de Resonancia por Spin del Electrón , Enlace de Hidrógeno , Modelos Moleculares , Estructura Molecular , Espectrofotometría Infrarroja

RESUMEN

This work reports the results of ultraviolet irradiation on the interaction of the phototoxic antipsychotic drug chlorpromazine (CPZ) with the sodium pump Na+, K+-ATPase. The study was performed by monitoring the fluorescence modifications of CPZ itself and of the specific probe anthroylouabain (AO). CPZ association with Na+, K+-ATPase was found to modify the kinetics of CPZ-photodegradation. It was demonstrated that UV irradiation produces a stable fluorescent photoproduct of CPZ covalently bound to Na+, K+-ATPase. The fluorescent probe AO, which specifically binds to the extracellular ouabain site of the pump, was used to localize the CPZ binding site. UV-irradiation of AO-labeled Na+, K+-ATPase treated with CPZ at concentration about 20 microM produced dose-dependent modifications of the AO fluorescence, e.g. increased quantum yield and blue shift. The results demonstrated that CPZ binds near the ouabain site. The photo-induced reaction of CPZ with AO-labeled Na+, K+-ATPase protected the ouabain site from the aqueous environment. It was also found that UV irradiation of CPZ-treated enzyme obstructs the binding of AO, which suggested occlusion of the ouabain site. This effect can be evaluated for a potential use of CPZ in photochemotherapy.

Asunto(s)

Antipsicóticos/metabolismo , Clorpromazina/metabolismo , Ouabaína/metabolismo , ATPasa Intercambiadora de Sodio-Potasio/metabolismo , Sitios de Unión , Fotoquímica , Espectrometría de Fluorescencia

RESUMEN

Reductive nitrosylation of the water-soluble iron derivatives of the cationic Fe(III)(TMPyP) and anionic Fe(III)(TPPS) porphyrins [where TMPyP=tetra-meso-(4-N-methylpyridiniumyl)porphinate and TPPS=tetra-meso-(4-sulfonatophenyl)porphinate] by the nitric oxide donor S-nitroso-N-acetylpenicillamine (SNAP) was studied using optical absorption spectroscopy and electron paramagnetic resonance. Nitrosylation rates were obtained, the reaction was found to be first order in the SNAP concentration and the stoichiometry of the reaction was one to one. The similarity between the obtained second-order rate constants for both porphyrins, k(TMPyP)=0.84 x 10(3)M(-1)s(-1) and k(TPPS)=0.97 x 10(3)M(-1)s(-1), suggested that the reaction mechanism is approximately independent of the nature of the porphyrin meso-substituents. A mechanism was proposed involving the hydrolysis of SNAP by an out of plane liganded H(2)O yielding the sulfenic acid of N-acetylpenicillamine and the transfer of NO(-) to Fe(III). The EPR (electron paramagnetic resonance) spectra of the SNAP- and gaseous NO-treated porphyrins were obtained and compared. The difference between the spectra of the cationic and anionic porphyrins indicates different local symmetry and Fe-N-O bond angle. SNAP-treatment produced much more resolved hyperfine structures than gaseous NO-treatment.

Asunto(s)

Metaloporfirinas/química , S-Nitroso-N-Acetilpenicilamina/química , Agua/química , Espectroscopía de Resonancia por Spin del Electrón/métodos , Compuestos Férricos/química , Cinética , Porfirinas/química , Solubilidad

RESUMEN

Binding of chlorpromazine (CPZ) and hemin (Hmn) to human (HSA) and bovine (BSA) serum albumin was studied by fluorescence quenching technique. Intrinsic fluorescences of BSA and HSA were measured by selectively exciting their tryptophan residues. Gradual quenching was observed by titration of both proteins with CPZ and Hmn. CPZ is a widely used anti-psychosis drug that causes severe side effects and strongly interacts with biomembranes, both in its lipidic and proteic regions. CPZ also interacts with blood components, influences bioavailability, and affects the function of several biomolecules. Albumin plays an important role in the transport and storage of hormones, ions, fatty acids and others substances, including CPZ, affecting the regulation of their plasmatic concentration. Hmn is an important ferric residue of hemoglobin that binds within the hydrophobic region of albumin with great specificity. Hmn added to HSA and BSA solutions at a molar ratio of 1:1 quenched about half of their fluorescence. Stern-Volmer plots obtained from experiments carried out at 25 and 35 degrees C showed the quenching of fluorescence of HSA and BSA by CPZ to be a collisional phenomenon. Hmn quenches fluorescence by a static process, which specifically indicates the formation of a complex. Our results suggest the prime binding site for CPZ and Hmn on both HSA and BSA to be near tryptophan residues.

Asunto(s)

Albúminas/química , Antipsicóticos/química , Clorpromazina/química , Albúmina Sérica/química , Espectrometría de Fluorescencia/métodos , Animales , Antipsicóticos/farmacología , Bovinos , Clorpromazina/farmacología , Relación Dosis-Respuesta a Droga , Hemina/química , Humanos , Modelos Químicos , Unión Proteica , Temperatura

RESUMEN

The nitrosylation of two water-soluble iron-porphyrins, the anionic Fe(III)-meso-tetrakis(p-sulfonatophenyl)porphyrin (FeTPPS(4)) and the cationic Fe(III)-meso-tetrakis(4-N-methylpyridiniumyl)porphyrin (FeTMPyP), by the nitric oxide donor S-nitroso-N-acetylpenicillamine (SNAP) was studied using optical absorption spectroscopy. The influence of ionic and non-ionic micelles on rates of nitric oxide transfer was investigated. Initially, the effect of the micelles on the pH-dependent equilibrium between monomeric and micro-oxo-dimeric species of the iron-porphyrins was examined. It is not affected in micelle-porphyrin systems with electric charges identical in sign. The non-ionic micelles of polidocanol induce a small negative pK shift. In contrast, the dimerization equilibrium of porphyrins in oppositely charged micellar phases is displaced to lower pH by approximately 2 units. Nitric oxide binding to monomers and micro-oxo-dimers was examined at pH 5.0 and 8.0, respectively. Contrary to nitrosylation by NO gas, SNAP induces reductive nitrosylation. There was no observed NO-Fe(III)porphyrin intermediate. Nitrosylation rates were obtained and compared in aqueous buffer and in micellar systems. Monomers nitrosylate much faster than micro-oxo-dimers. Oppositely charged micelles prevent nitrosylation of the iron-porphyrins or considerably enhance nitrosylation times. Nitrosylation rates are comparable to transnitrosylation rates between several S-nitrosothiols and thiol-containing proteins, suggesting biological relevance for the process.

Asunto(s)

Compuestos Férricos/química , Donantes de Óxido Nítrico/química , Óxido Nítrico/química , Porfirinas/química , S-Nitroso-N-Acetilpenicilamina/química , Dimerización , Compuestos Férricos/metabolismo , Concentración de Iones de Hidrógeno , Cinética , Óxido Nítrico/metabolismo , Donantes de Óxido Nítrico/metabolismo , Porfirinas/metabolismo , S-Nitroso-N-Acetilpenicilamina/metabolismo , Solubilidad , Espectrofotometría/métodos , Volumetría

RESUMEN

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.

Asunto(s)

Inhibidores de la Colinesterasa/metabolismo , Metil Paratión/metabolismo , Albúmina Sérica Bovina/metabolismo , Animales , Unión Competitiva , Bovinos , Fluorescencia , Humanos , Técnicas In Vitro , Unión Proteica , Espectrometría de Fluorescencia , Triptófano/química