title: Probing the emitter site of Renilla luciferase using small organic molecules; an attempt to understand the molecular architecture of the emitter site.
abstract: Renilla luciferase is a sensitive enzyme and has wide applications in biotechnology such as drug screening. Previous studies have tried to show the catalytic residues, nevertheless, the accurate architecture and molecular behavior of its emitter site remains uncharacterized. In this study, the activity of Renilla luciferase, in the presence of two small organic molecules including dimethyl sulfoxide (DMSO) and isopropanol was considered and the structure was studied by circular dichroism (CD) and fluorescence spectroscopy. Moreover, the interaction of small organic molecules with the Renilla luciferase was studied using molecular dynamics simulations. Kinetics studies showed that at low concentration of DMSO (16.6-66mM) and isopropanol (19.3-76mM) the Kmchanged and a competitive inhibition pattern was observed. Moreover, spectroscopy studies reveled that the changes of activity of Renilla luciferase in the presence of low concentrations of small organic molecules was not associated with structural collapse or severe changes in the enzyme conformation. Molecular dynamics simulations indicated that DMSO and isopropanol, as probing molecules, were both able to bind to the emitter site and remained with the residues of the emitter site. Based on the probing data, the architecture of the emitter site in the "non-binding" model was proposed.
authors.affiliation: Department of Biology, University of Isfahan, Isfahan, Iran.
authors.forename: Farajollah
authors.initials: F
authors.lastname: Salehi
authors.affiliation: Department of Biology, University of Isfahan, Isfahan, Iran. Electronic address: Sci_rahman@yahoo.com.
authors.forename: Rahman
authors.initials: R
authors.lastname: Emamzadeh
authors.affiliation: Monoclonal Antibody Research Center, Avicenna Research Institute, ACECR, Tehran, Iran.
authors.forename: Mahboobeh
authors.initials: M
authors.lastname: Nazari
authors.affiliation: Department of Biology, University of Isfahan, Isfahan, Iran.
authors.forename: Seyed Mohammad Mahdi
authors.initials: SM
authors.lastname: Rasa
mesh_terms: D019840:2-Propanol / Q000494:pharmacology*; D004121:Dimethyl Sulfoxide / Q000494:pharmacology*; D007700:Kinetics; D049410:Luciferases, Renilla / Q000737:chemistry* / Q000378:metabolism*; D056004:Molecular Dynamics Simulation; D011487:Protein Conformation
chemical_list: D049410:Luciferases, Renilla; D019840:2-Propanol; D004121:Dimethyl Sulfoxide
keywords: Enzyme emitter site; MD simulation; Renilla luciferase; Small organic molecules