title: Urea-dependent unfolding of HIV-1 protease studied by circular dichroism and small-angle X-ray scattering.
abstract: HIV-1 protease is responsible for the maturation of infective virions, and is one of the targets of drugs against AIDS. It is an aspartic protease with a 99-resiude polypeptide dimerized. Previous study with fluorescence and sedimentation measurements revealed that the protein was unfolded with concomitant dissociation of the subunits. In the present study, we investigated urea-dependent unfolding of HIV-1 protease with CD and SAXS in order to monitor the secondary structure and the global size and shape of the molecule, respectively. The unfolding parameters estimated by both methods were almost the same, indicating that the dissociation of the subunits accompanied the disruption of their internal structures. This is in line with the previous results, and moreover some residual structures were suggested to be present in the unfolded state. The distinct difference, as compared with the unfolding of pepsin, was interpreted from the point of their molecular architectures.
authors.affiliation: School of Life Science, Tokyo University of Pharmacy and Life Sciences, Horinouchi, Hachioji, Tokyo 192-0392, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kogo
authors.forename: Kayoko
authors.initials: K
authors.lastname: Takeuchi
authors.forename: Hideshi
authors.initials: H
authors.lastname: Inoue
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kihara
authors.forename: Masaki
authors.initials: M
authors.lastname: Kojima
authors.forename: Kenji
authors.initials: K
authors.lastname: Takahashi
mesh_terms: D002942:Circular Dichroism; D016333:HIV Protease / Q000737:chemistry* / Q000378:metabolism; D010434:Pepsin A / Q000737:chemistry / Q000378:metabolism; D011489:Protein Denaturation / Q000187:drug effects; D017510:Protein Folding / Q000187:drug effects*; D017433:Protein Structure, Secondary / Q000187:drug effects; D053838:Scattering, Small Angle; D014508:Urea / Q000737:chemistry / Q000494:pharmacology*; D014961:X-Ray Diffraction
chemical_list: D014508:Urea; D016333:HIV Protease; C514803:p16 protease, Human immunodeficiency virus 1; D010434:Pepsin A