Background: Recently, the small molecule that inhibits the human copper-trafficking
proteins Atox1 and CCS was reported, which suggested that small molecule has an effect on the
copper regulation system in the cell. The copper chaperones CopC is regarded as a redox switch
and possess barrel structure, thus the interaction between CopC and small molecules could give
helpful information to elucidate the copper regulation mechanism. In addition, porphyrins play an
important role in the metabolism of living body. In the early-stage tumors, porphyrins were usually
used to diagnosis. After the amphiphilic porphyrins were given by intravenous injection, serum
albumins and serum proteins were the most usual carrier to transfer them. Then these molecules can
accumulate in malignant tumours and contact with cancer cells. Obviously, in drug distribution and
efficacy, investigation of the interaction between the porphyrins and protein is an important
research area. Obviously, in drug distribution and efficacy, investigation of the interaction between
the porphyrins and protein is an important research area.
Objective: In this article, our motivation is to establish a relation between Tetrakis (4-
carboxylphenyl) porphyrin and CopC.
Methods: In this article, we propose a framework for achieving our aforementioned object. Firstly,
FTIR spectra and CD were used to detect the structure changes of CopC. Secondly, the
fluorescence spectroscopic and UV-Vis spectra were used to measure quenching mechanism,
binding distance, binding site and binding distance. Using Tb 3+ as a probe to detect the interaction
between CopC and TCPP. Finally, molecular docking methods was used to show the results more
Results: Following the proposed framework, firstly, FTIR and CD results indicated that the CopC
conformation was changed by TCPP. The β-sheet content was reduced and the random coil content
was increased. Secondly, fluorescence spectra data indicated that the combination ratio of TCPPCopC
was 1:1, and the inclusion constant is (5.88 ± 0.12) × 10 5 M -1 . In addition, Tb 3+ was used
as a probe to detect the interaction between CopC and TCPP. The result further verified that CopC
can interact with TCPP. The thermodynamic parameters of interaction between CopC and TCPP
(ΔH, ΔS) indicated that the force between CopC and TCPP was mainly hydrophobic interaction.
Finally, the distance between tryptophan in CopC and TCPP was calculated through forster energy
transfer and molecular docking.
Conclusion: The results revealed that TCPP can form 1:1 complex with CopC, and the binding
constant has been calculated to be (5.88 ± 0.12) × 10 5 M -1 . In addition, it was revealed that
TCPP quench the fluorescence of CopC by the static quenching mechanism and the binding site n
equals one. The formation of CopC-TCPP complex depended on the hydrophobic force and the
distance between TCPP and tryptophan residue in CopC was 2.07 nm.