Investigation on the Interaction between Tetrakis (4-carboxylphenyl) Porphyrin and CopC by Spectroscopy and Docking Methods.

Abstract

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. In this article, our motivation is to establish a relation between Tetrakis (4- carboxylphenyl) porphyrin and CopC. 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 vivid. 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. 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.