title: Relaxation dynamics of piroxicam structures within human serum albumin protein.
abstract: We report on steady-state and ps-time-resolved emission studies of piroxicam (1) drug within human serum albumin (HSA) protein in cyclodextrin and in neat solvents. The steady-state results indicate that 1 binds to HSA protein and that two binding sites are involved. The fluorescence decays corresponding to site I in subdomain IIA and to site II in subdomain IIIA have time constants of approximately 60 ps and approximately 360 ps, respectively. The results suggest that the anion forms bind to site I, whereas the zwitterionic ones bind to site II. The energy-transfer process from excited tryptophan to 1 can occur with moderate efficiency (50%). The rotational time of 1 encapsulated by HSA indicates diffusion within the protein. These findings can be used for a better understanding of piroxicam and HSA interactions.
authors.affiliation: Departamento de Química Física, ICAM, and Sección de Químicas, Facultad de Ciencias del Medio Ambiente, Universidad de Castilla-La Mancha, Avda. Carlos III, S.N., 45071, Toledo, Spain.
authors.forename: Maged
authors.initials: M
authors.lastname: El-Kemary
authors.forename: Michał
authors.initials: M
authors.lastname: Gil
authors.forename: Abderrazzak
authors.initials: A
authors.lastname: Douhal
mesh_terms: D016880:Anisotropy; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry*; D001665:Binding Sites; D004735:Energy Transfer; D006801:Humans; D006860:Hydrogen Bonding; D007477:Ions; D008958:Models, Molecular; D008968:Molecular Conformation; D010894:Piroxicam / Q000737:chemistry*; D011487:Protein Conformation; D012709:Serum Albumin / Q000737:chemistry*; D012996:Solutions; D014364:Tryptophan / Q000737:chemistry; D014867:Water; D047392:beta-Cyclodextrins
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D007477:Ions; D012709:Serum Albumin; D012996:Solutions; D047392:beta-Cyclodextrins; D014867:Water; D010894:Piroxicam; D014364:Tryptophan