title: Study on the interaction of 6-(2-morpholin-4-yl-ethyl)-6H-indolo [2,3-b]quinoxaline hydrochloride with human serum albumin by fluorescence spectroscopy.
abstract: Under physiological conditions, in vitro interaction between the bio-active substance 6-(2-morpholin-4-yl-ethyl)-6H-indolo[2,3-b]quinoxaline hydrochloride (MIQ) and human serum albumin (HSA) was investigated at an excitation wavelength 260 nm and at different temperatures (298 K, 308 K and 313 K) by fluorescence emission spectroscopy. From spectral analysis, MIQ showed a strong ability to quench the intrinsic fluorescence of HSA through a static quenching procedure. The binding constant is estimated asKA=  2.55  ×  10-4l · mol-1at 298 K. Based on the thermodynamic parameters evaluated from the van 't Hoff equation, the enthalpy change (ΔH°) and entropy change (ΔS°) were derived to be negative values. A value of 2.37 nm for the average distance r between MIQ (acceptor) and tryptophan residues of HSA (donor) was derived from the fluorescence resonance energy transfer. UV/vis absorption spectra were used to confirm the quenching mechanism.
authors.affiliation: A V Bogatsky Physico-chemical Institute of the National Academy of Sciences of Ukraine, 86 Lustdorfskaya doroga, 65080 Odessa, Ukraine.
authors.forename: A
authors.initials: A
authors.lastname: Yegorova
authors.forename: I
authors.initials: I
authors.lastname: Leonenko
authors.forename: Yu
authors.initials: Y
authors.lastname: Scrypynets
authors.forename: G
authors.initials: G
authors.lastname: Maltsev
authors.forename: V
authors.initials: V
authors.lastname: Antonovich
mesh_terms: D001665:Binding Sites; D005453:Fluorescence; D006801:Humans; D011485:Protein Binding; D011810:Quinoxalines / Q000032:analysis*; D000075462:Serum Albumin, Human; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013816:Thermodynamics
chemical_list: D011810:Quinoxalines; D000075462:Serum Albumin, Human