Study on the interaction of a cyanine dye with human serum transferrin.
Complexation between the primary carrier of ligands in blood plasma, human serum transferrin (Tf), and a cyanine dye, 3,3'-di(3-sulfopropyl)-4,5,4',5'-dibenzo-9-phenyl-thiacarbocyanine-triethylam monium salt (PTC) was investigated using fluorescence spectra, UV/Vis absorption spectra, synchronous fluorescence spectra, circular dichroism (CD) and molecular dynamic docking. The experimental results demonstrate that the formation of PTC-Tf complex is stabilized by van der Waal's interactions and hydrogen bonds, and the binding constants were found to be 8.55 × 10(6), 8.19 × 10(6) and 1.75 × 10(4) M(-1). Moreover, fluorescence experiments prove that the operational mechanism for the fluorescence quenching is static quenching and non-radiative energy transfer. Structural investigation of the PTC-Tf complexes via synchronous fluorescence spectra and CD showed that the structure of Tf became more stable with a major increase in the α-helix content and increased polarity around the tryptophan residues after PTC binding. In addition, molecular modeling highlights the residues located in the N-lobe, which retain high affinity for PTC. The mode of action of the PTC-Tf complex is illustrated by these results, and may provide an effective pathway for the transport and targeted delivery of antitumor agents.
College of Chemical Engineering, Hebei United University, Tangshan, Hebei, 063009, China.
Xiu-feng
XF
Zhang
College of Chemical Engineering, Hebei United University, Tangshan, Hebei, 063009, China.
Lei
L
Chen
Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.
Qian-fan
QF
Yang
Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.
Qian
Q
Li
College of Chemical Engineering, Hebei United University, Tangshan, Hebei, 063009, China.
Xiao-ran
XR
Sun
College of Chemical Engineering, Hebei United University, Tangshan, Hebei, 063009, China.
Hong-bo
HB
Chen
College of Chemical Engineering, Hebei United University, Tangshan, Hebei, 063009, China.
Guang
G
Yang
Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.
Ya-lin
YL
Tang
D002232:Carbocyanines / Q000737:chemistry*; D004396:Coloring Agents / Q000737:chemistry*; D005453:Fluorescence; D006801:Humans; D007700:Kinetics; D011485:Protein Binding; D017433:Protein Structure, Secondary; D013050:Spectrometry, Fluorescence; D014168:Transferrin / Q000737:chemistry*
C548165:3,3'-di(3-sulfopropyl)-4,5,4',5'-dibenzo-9-ethyl-thiacarbocyanine; D002232:Carbocyanines; D004396:Coloring Agents; D014168:Transferrin
conformational transition; cyanine dye; docking; fluorescent quenching; transferrin