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Abstract: The mutual interaction of riboflavin (RF) with bovine serum albumin (BSA) was investigated using fluorescence spectroscopy under simulative physiological conditions. The fluorescence quenching mechanism of BSA by RF should belong to dynamic quenching according to the Stern–Volmer equation, but also the effect of ground complex formation and energy transfer could not be completely precluded in BSA–RF system. The binding constants and the corresponding thermodynamic parameters at different temperatures were calculated, which indicated the presence of hydrophobic forces between RF and BSA. The averaged binding distance between riboflavin and BSA was also obtained based on the theory of FÖrster’s non-radiation energy transfer. Moreover, the effect of riboflavin on the conformation of BSA was analyzed using synchronous fluorescence. The effects of some common ions Cu2+, Zn2+, Ca2+, and Mg2+ on the binding constant between riboflavin and BSA were also examined. [Copyright &y& Elsevier]

Abstract: The eight-coordinate (enH2)[YIII(pdta)(H2O)]2·10H2O (en=ethylenediamine and H4pdta=1,3-propylenediamine-N,N,N′,N′-tetraacetic acid) was synthesized, meanwhile its molecular and crystal structures were determined by single-crystal X-ray diffraction technology. The interaction between [YIII(pdta)(H2O)]2 2− and bovine serum albumin (BSA) was investigated by UV–vis and fluorescence spectra. The results indicate that [YIII(pdta)(H2O)]2 2− quenched effectively the intrinsic fluorescence of BSA via a static quenching process with the binding constant (K a) of the order of 104. Meanwhile, the binding and damaging sites to BSA molecules were also estimated by synchronous fluorescence. Results indicate that the hydrophobic environments around Trp and Tyr residues were all slightly changed. The thermodynamic parameters (ΔG =−25.20kJmol−1, ΔH= −26.57kJmol−1 and ΔS= −4.58Jmol−1 K−1) showed that the reaction was spontaneous and exothermic. What is more, both ΔH and ΔS were negative values indicated that hydrogen bond and Van der Waals forces were the predominant intermolecular forces between [YIII(pdta)(H2O)]2 2− and BSA. [ABSTRACT FROM AUTHOR]