Binding studies of lincosamide antibiotic drug clindamycin phosphate to human serum albumin by fluorescence, 3D, and circular dichroism spectroscopy

The binding interaction between clindamycin phosphate and human serum albumin (HSA) has been studied by multiple spectroscopic techniques. The binding constants at three temperatures (288, 298, and 308 K) were 2.12, 3.74, and 6.95 × 10 4 dm 3 mol −1 , respectively, and the number of binding sites were 1.15, 1.18, and 1.22, respectively; thermodynamic parameters Δ H o (43.76 kJ mol −1 ), Δ G o (−20.460 kJ mol −1 ), and Δ S o (215.50 J K −1 mol −1 ) were calculated. The distance r between donor and acceptor was obtained ( r = 6.37 nm) according to the Förster theory of non-radiative energy transfer. In addition, synchronous fluorescence spectroscopy, circular dichroism, and 3D fluorescence spectroscopy showed that the binding of clindamycin phosphate to HSA changed the secondary structure of the protein. Graphical Abstract