Study on the interaction of paeoniflorin with human serum albumin (HSA) by spectroscopic and molecular docking techniques

Abstract

The interaction of paeoniflorin with human serum albumin (HSA) was investigated using fluorescence, UV–vis absorption, circular dichroism (CD) spectra and molecular docking techniques under simulative physiological conditions. The results clarified that the fluorescence quenching of HSA by paeoniflorin was a static quenching process and energy transfer as a result of a newly formed complex (1:1). Paeoniflorin spontaneously bound to HSA in site I (subdomain IIA), which was primarily driven by hydrophobic forces and hydrogen bonds (ΔH° = − 9.98 kJ mol−1, ΔS° = 28.18 J mol−1 K−1). The binding constant was calculated to be 1.909 × 103 L mol−1 at 288 K and it decreased with the increase of the temperature. The binding distance was estimated to be 1.74 nm at 288 K, showing the occurrence of fluorescence energy transfer. The results of CD and three-dimensional fluorescence spectra showed that paeoniflorin induced the conformational changes of HSA. Meanwhile, the study of molecular docking also indicated that paeoniflorin could bind to the site I of HSA mainly by hydrophobic and hydrogen bond interactions.

Interaction between Saikosaponin D, Paeoniflorin, and Human Serum Albumin

“…In PF-HSA binding, PF at 1 μM slightly increased the α-helical content. On the contrary, PF at 25 μM slightly decreased the α-helical content, as previously shown [ 24 ]. In short, PF alone has a little effect on the helical structure of HSA.…”

“…At Δλ = 60 nm, a blue shift of 5 nm (from 278 to 273 nm) formed at maximum emission. Undoubtedly, the difference between the present and reported study is mainly attributed to the concentration of PF [ 24 ]. These findings reveal that the amino acid residues in the vicinity of the fluorophore are disturbed by PF at both low and high concentrations.…”

“…As for HSA fluorescence intensity, our findings are consistent with prior studies showing the fluorescence of 1.5 μM HSA is about 4000 [ 31 ]. However, the fluorescence of 1 μM HSA in the present study was much above that (<1200) of 10 μM HSA [ 24 ]. This significant difference may mainly be ascribed to HSA itself, set-up of parameter measurements, sensitivity of light, filter, or detector, reaction system, and experimental conditions.…”

“…As shown in Figure 2 and Table 1 , examination of fluorescence peaks revealed a 5 nm blue shift for HSA following binding to SSD, and a 3 nm blue shift for HSA following PF binding. Unlike to these findings, a blue shift for HSA-PF at high-dose binding was not reported [ 24 ]. Although the SSD-induced shift was slightly greater to that of the PF-induced shift, this suggests that SSD and PF both induce conformational changes in HSA.…”

“…Thus, the investigation of the binding between SSD/PF and HSA is of important significance in life sciences, chemistry, and medicine [ 19 , 20 , 21 , 22 , 23 ]. A previous study reported that PF alone at high concentrations binds HSA [ 24 ]. The present study is focused on the binding of SSD and PF at low concentrations with HSA.…”