title: Structural and drug-binding properties of alpha(1)-acid glycoprotein in reverse micelles.
abstract: Alpha(1)-acid glycoprotein (AGP) is a glycoprotein that consists of 183 amino acid residues and five carbohydrate chains and binds to neutral and basic drugs. We examined the structural properties and ligand-binding capacity of AGP in interactions with reverse micelles. Also, detailed information was obtained by comparing several different states of AGP. Interaction with reverse micelles induced a unique conformational transition (beta-sheet to alpha-helices) in AGP and decreased the binding capacity for the basic drug, chlorpromazine and the steroid hormone, progesterone to AGP. These structural conformations are very similar to those observed under conditions of acidity and high ionic strength (pH 2.0, 1.5 M NaCl). This structure seems to be an intermediate between the native state and the denatured state, possibly a molten globule. The present results suggest that when AGP interacts with the biomembrane, it undergoes a structural transition to a unique structure that differs from the native and denatured states and has a reduced ligand-binding capacity.
authors.affiliation: Biopharmaceutics Laboratory, Faculty of Pharmaceutical Science, Kumamoto University, 5-1 Oe-honmachi, Kumamoto 862-0973, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Nishi
authors.forename: Norifumi
authors.initials: N
authors.lastname: Sakai
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Komine
authors.forename: Toru
authors.initials: T
authors.lastname: Maruyama
authors.forename: H Brian
authors.initials: HB
authors.lastname: Halsall
authors.forename: Masaki
authors.initials: M
authors.lastname: Otagiri
mesh_terms: D002746:Chlorpromazine / Q000493:pharmacokinetics; D002942:Circular Dichroism; D001728:Dicumarol / Q000493:pharmacokinetics; D007700:Kinetics; D008823:Micelles; D009961:Orosomucoid / Q000737:chemistry* / Q000378:metabolism*; D011374:Progesterone / Q000493:pharmacokinetics; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary
chemical_list: D008823:Micelles; D009961:Orosomucoid; D011374:Progesterone; D001728:Dicumarol; D002746:Chlorpromazine