title: New insights into xanthine oxidase behavior upon heating using spectroscopy and in silico approach.
abstract: Thermal dependent conformational changes of xanthine oxidase (XOD) were studied using sensitive and non-destructive methods like fluorescence spectroscopy and molecular modeling in the temperature range of 25-85°C. Intrinsic fluorescence studies showed that the microenvironment of tryptophan and tyrosine residues becomes more exposed to solvent as the temperature increased up to 85°C, whereas in case of flavin cofactor is rather conserved. At higher temperatures, the flavin adenine dinucleotide is displaced from the core of the protein, but is not fully released as shown by the Stern Volmer quenching constant and accessible fraction of the cofactor. Anyway, no significant changes in the structure of XOD monomer were identified after running molecular dynamics simulations at temperatures 25°C, 65°C and 85°C. Therefore, we can conclude that the most important changes in the protein structure at thermal treatment mainly consist on molecular aggregation and dissociation events.
authors.affiliation: Dunarea de Jos University of Galati, Faculty of Food Science and Engineering, Domnească Street 111, 800201 Galati, Romania.
authors.forename: Loredana
authors.initials: L
authors.lastname: Dumitrașcu
authors.affiliation: Dunarea de Jos University of Galati, Faculty of Food Science and Engineering, Domnească Street 111, 800201 Galati, Romania.
authors.forename: Nicoleta
authors.initials: N
authors.lastname: Stănciuc
authors.affiliation: Dunarea de Jos University of Galati, Faculty of Food Science and Engineering, Domnească Street 111, 800201 Galati, Romania. Electronic address: Iuliana.Aprodu@ugal.ro.
authors.forename: Iuliana
authors.initials: I
authors.lastname: Aprodu
mesh_terms: D000818:Animals; D002417:Cattle; D002942:Circular Dichroism; D004138:Dinitrocresols / Q000737:chemistry; D005182:Flavin-Adenine Dinucleotide / Q000737:chemistry*; D006358:Hot Temperature; D008892:Milk / Q000737:chemistry; D056004:Molecular Dynamics Simulation; D011487:Protein Conformation; D055503:Protein Multimerization; D021122:Protein Subunits / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D014364:Tryptophan / Q000737:chemistry; D014443:Tyrosine / Q000737:chemistry; D014969:Xanthine Oxidase / Q000737:chemistry* / Q000302:isolation & purification
chemical_list: D004138:Dinitrocresols; D021122:Protein Subunits; D005182:Flavin-Adenine Dinucleotide; C024132:4,6-dinitro-o-cresol; D014443:Tyrosine; D014364:Tryptophan; D014969:Xanthine Oxidase
keywords: Fluorescence; Molecular events; Structural changes; Synchronous spectra; Xanthine oxidase