Davide Barreca1, Giuseppina Laganà1, Giovanni Toscano1, Pietro Calandra2, Mikhail A Kiselev3, Domenico Lombardo4, Ersilia Bellocco5. 1. Dipartimento di Scienze chimiche, biologiche, farmaceutiche ed ambientali, Università di Messina. Viale F. Stagno d'Alcontres 31, 98166 Messina, Italy. 2. Consiglio Nazionale delle Ricerche, Istituto per lo Studio dei Materiali Nanostrutturati, Via Salaria km 29.300, Monterotondo Stazione, 00015 Roma, Italy. 3. Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Ulica Joliot-Curie 6, Dubna, Moscow 141980, Russia. 4. Consiglio Nazionale delle Ricerche, Istituto per i Processi Chimico-Fisici, Viale F. Stagno d'Alcontres 37, 98158 Messina, Italy. 5. Dipartimento di Scienze chimiche, biologiche, farmaceutiche ed ambientali, Università di Messina. Viale F. Stagno d'Alcontres 31, 98166 Messina, Italy. Electronic address: ebellocco@unime.it.
Abstract
BACKGROUND: Interactions of ligands with proteins imply changes in the properties of the macromolecules that may deeply modify their biological activities and conformations and allow them to acquire new and, sometimes, unexpected abilities. The flavonoid phloretin has several pharmacological properties that are starting to be elucidated, one of which is the well-known inhibition of glucose transport. METHODS: The interactions of phloretin to human serum albumin have been investigated by fluorescence, UV-visible, FTIR spectroscopy, native electrophoresis, protein ligand docking studies, fluorescence and scanning electron microscopy. RESULTS: Spectroscopic investigations suggest that the flavonoid binds to human serum albumin inducing a decrease in α-helix structures as shown by deconvolution of FTIR Amide I' band. Fluorescence and displacement studies highlight modifications of environment around Trp214 with the primary binding site located in the Sudlow's site I. In the hydrophobic cavity of subdomain IIA, molecular modeling studies suggest that phloretin is in non-planar conformation and hydrogen-bonded with Ser202 and Ser454. These changes make HSA able to withstand protein degradation due to HCLO and fibrillation. GENERAL SIGNIFICANCE: Our work aims to open new perspectives as far as the binding of flavonoids to HSA are concern and shows as the properties of both compounds can be remarkable modified after the complex formation, resulting, for instance, in a protein structure much more resistant to oxidation and fibrillation. This article is part of a Special Issue entitled "Science for Life" Guest Editor: Dr. Austen Angell, Dr. Salvatore Magazù and Dr. Federica Migliardo.
BACKGROUND: Interactions of ligands with proteins imply changes in the properties of the macromolecules that may deeply modify their biological activities and conformations and allow them to acquire new and, sometimes, unexpected abilities. The flavonoidphloretin has several pharmacological properties that are starting to be elucidated, one of which is the well-known inhibition of glucose transport. METHODS: The interactions of phloretin to human serum albumin have been investigated by fluorescence, UV-visible, FTIR spectroscopy, native electrophoresis, protein ligand docking studies, fluorescence and scanning electron microscopy. RESULTS: Spectroscopic investigations suggest that the flavonoid binds to human serum albumin inducing a decrease in α-helix structures as shown by deconvolution of FTIR Amide I' band. Fluorescence and displacement studies highlight modifications of environment around Trp214 with the primary binding site located in the Sudlow's site I. In the hydrophobic cavity of subdomain IIA, molecular modeling studies suggest that phloretin is in non-planar conformation and hydrogen-bonded with Ser202 and Ser454. These changes make HSA able to withstand protein degradation due to HCLO and fibrillation. GENERAL SIGNIFICANCE: Our work aims to open new perspectives as far as the binding of flavonoids to HSA are concern and shows as the properties of both compounds can be remarkable modified after the complex formation, resulting, for instance, in a protein structure much more resistant to oxidation and fibrillation. This article is part of a Special Issue entitled "Science for Life" Guest Editor: Dr. Austen Angell, Dr. Salvatore Magazù and Dr. Federica Migliardo.