ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

A spectroscopic and molecular docking study of interactions of tetracarboxyphenyl porphyrin and chlorin e6 with bovine serum albumin

Jonathan Osiris Vicente-Escobar, Miguel A. García-Sánchez, F. González, S. Cipagauta-Díaz, and A. Estrella González

Departmento de Química, Universidad Autónoma Metropolitana-Iztapalapa, Ciudad de México, México

E-mail: mags@xanum.uam.mx

Received: 6 December 2020  Accepted: 20 April 2021

Abstract:

Abstract

In order to use tetrapyrrolic macrocyclic species in medical applications, the interactions of bovine serum albumin (BSA) with tetrakis-para-carboxyphenyl-porphyrin (H₂T(p-COOH) PP or TCPP) and Chlorin e6 (Ce6), under different conditions, were investigated by fluorescence spectroscopy and UV–VIS absorption spectroscopy and contrasted with molecular docking study. The binding constant (K_b) values at three different temperatures were calculated using the modified Stern–Volmer equation. The enthalpy change (ΔH) and entropy change (ΔS) were determined based on the van’t Hoff equation. The results of fluorescence spectroscopy indicate that static quenching is the dominant process resulting from the BSA-TCPP complex formation. In the case of the BSA-Ce6 complex, static quenching was confirmed too. Thermodynamic analysis indicated that hydrogen bonds and van der Waals interactions were the predominant intermolecular forces in the binding process to stabilize the BSA-TCPP and BSA-Ce6 complexes. Molecular docking suggests that the probable binding site of the two macrocyclic species at BSA occurs in the vicinity of the Trp-134 residue. Molecular modeling study further confirmed interactions in the binding mode obtained experimentally.

Graphic abstract

Keywords: Chlorin e6; Tetracarboxyphenyl porphyrin; Bovine serum albumin; Molecular docking

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-021-01670-3

Chemical Papers 75 (9) 4501–4515 (2021)