title: Characteristics of the Protoporphyrin IX Binding Sites on Human Serum Albumin Using Molecular Docking.
abstract: Human serum albumin (HSA) is the main plasma protein responsible for a distribution of drugs in the human circulatory system. The binding to HSA is one of the factors that determines both the pharmacological actions and the side effects of drugs. The derivative of heme, protoporphyrin IX (PpIX), is a hydrophobic photosensitizer widely used in photodynamic diagnosis and therapy of various malignant disorders. Using absorption and fluorescence spectroscopy, it has been demonstrated that PpIX forms complexes with HSA. Its binding sites in the tertiary structure of HSA were found in the subdomains IB and IIA. PpIX binds to HSA in one class of binding sites with the association constant of 1.68 × 10⁵ M-1and 2.30 × 10⁵ M-1for an excitation at wavelength λex= 280 nm and 295 nm, respectively. The binding interactions between HSA and PpIX have been studied by means of molecular docking simulation using the CLC Drug Discovery Workbench (CLC DDWB) computer program. PpIX creates a strong 'sandwich-type' complex between its highly conjugated porphine system and aromatic side chains of tryptophan and tyrosine. In summary, fluorescent studies on binding interactions between HSA and PpIX have been confirmed by the results of computer simulation.
authors.affiliation: Department of General and Vascular Surgery, Regional Specialist Hospital, Bialska 104/118, 42-218 Częstochowa, Poland. leszeksulkowski@icloud.com.
authors.forename: Leszek
authors.initials: L
authors.lastname: Sułkowski
authors.affiliation: Department of Physical Pharmacy, School of Pharmacy with the Division of Laboratory Medicine in Sosnowiec, Medical University of Silesia, Jagiellońska 4, 41-200 Sosnowiec, Poland. bpawelczak@sum.edu.pl.
authors.forename: Bartosz
authors.initials: B
authors.lastname: Pawełczak
authors.affiliation: Department of Physical Pharmacy, School of Pharmacy with the Division of Laboratory Medicine in Sosnowiec, Medical University of Silesia, Jagiellońska 4, 41-200 Sosnowiec, Poland. mchudzik@sum.edu.pl.
authors.forename: Mariola
authors.initials: M
authors.lastname: Chudzik
authors.affiliation: Department of Physical Pharmacy, School of Pharmacy with the Division of Laboratory Medicine in Sosnowiec, Medical University of Silesia, Jagiellońska 4, 41-200 Sosnowiec, Poland. mmaciazek@sum.edu.pl.
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Maciążek-Jurczyk
mesh_terms: D020816:Amino Acid Motifs; D001665:Binding Sites; D006801:Humans; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D062105:Molecular Docking Simulation; D011524:Protoporphyrins / Q000737:chemistry*; D012709:Serum Albumin / Q000737:chemistry*; D013050:Spectrometry, Fluorescence
chemical_list: D011524:Protoporphyrins; D012709:Serum Albumin; C028025:protoporphyrin IX
keywords: UV-VIS; emission fluorescence; human serum albumin; molecular docking; photodynamic diagnosis; photodynamic therapy; protoporphyrin IX