Multi-spectroscopic study on interaction of bovine serum albumin with lomefloxacin-copper(II) complex.
The binding reactions of lomefloxacin-copper(II) complex (LMF-Cu) or LMF to bovine serum albumin (BSA) in physiological solution were investigated by multi-spectroscopy. The binding constant, the number of binding sites and the binding distance between LMF-Cu or LMF and BSA were obtained by a fluorescence quenching method and according to the mechanism of Forster-type dipole-dipole non-radioactive energy-transfer, respectively. Enthalpy and entropy changes for two systems were calculated to be -7.970 kJ mol(-1) and 47.438 J mol(-1)K(-1) for LMF-BSA, -12.469 kJ mol(-1) and 33.542 J mol(-1)K(-1) for LMF-Cu-BSA, respectively. The highly positive values observed for the entropy give evidence for a strong interaction. The values of DeltaH and DeltaS in two systems are similar, indicating that electrostatic interactions in two systems play major role. The effect of LMF-Cu or LMF on the conformation of BSA was also analyzed by synchronous fluorescence, three-dimensional fluorescence and circular dichroism spectra. The results showed that the presence of Cu ion in LMF-Cu can affect the conformation of BSA to some degree. All the results revealed that the addition of copper ion promotes the interaction of lomefloxacin with bovine serum albumin.
Lu
Jian-Quan
JQ
Hubei Key Laboratory of Bioanalytical Technique, Hubei Normal University, Huangshi 435002, China. jianquanlu@eyou.com
Jin
Fen
F
Sun
Ting-Quan
TQ
Zhou
Xing-Wang
XW
D000818:Animals; D002417:Cattle; D002942:Circular Dichroism; D003300:Copper / Q000737:chemistry* / Q000378:metabolism; D004735:Energy Transfer; D005453:Fluorescence; D024841:Fluoroquinolones / Q000737:chemistry* / Q000378:metabolism; D011487:Protein Conformation; D012710:Serum Albumin, Bovine / Q000737:chemistry* / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics
D024841:Fluoroquinolones; D012710:Serum Albumin, Bovine; D003300:Copper; C053091:lomefloxacin