title: Entrapment and inhibition of human immunodeficiency virus proteinase by alpha 2-macroglobulin and structural changes in the inhibitor.
abstract: The inhibitory effect of alpha 2-macroglobulin (alpha 2M), a major plasma proteinase inhibitor, on human immunodeficiency virus (HIV) proteinase was investigated. The activity of HIV proteinase toward the Moloney murine sarcoma virus-derived gag protein (a high-molecular-mass substrate) was found to be inhibited by alpha 2M at pH 5.5-7.4. On the other hand, the activity toward the B chain of oxidized insulin (a low-molecular-mass substrate) was scarcely inhibited. The complex of alpha 2M and HIV proteinase was isolated by gel filtration and the enzyme was shown to be significantly protected by the complex formation from autoinactivation under nonreducing conditions. The stoichiometry of the complex formation was found to be 2:1 (enzyme: alpha 2M, mol/mol). These results demonstrate the entrapment and concomitant inhibition of HIV proteinase by alpha 2M.
authors.affiliation: Department of Biophysics and Biochemistry, Faculty of Science, University of Tokyo.
authors.forename: S B
authors.initials: SB
authors.lastname: Athauda
authors.forename: E
authors.initials: E
authors.lastname: Ido
authors.forename: H
authors.initials: H
authors.lastname: Arakawa
authors.forename: M
authors.initials: M
authors.lastname: Nishigai
authors.forename: H
authors.initials: H
authors.lastname: Kyushiki
authors.forename: Y
authors.initials: Y
authors.lastname: Yoshinaka
authors.forename: T
authors.initials: T
authors.lastname: Takahashi
authors.forename: A
authors.initials: A
authors.lastname: Ikai
authors.forename: J
authors.initials: J
authors.lastname: Tang
authors.forename: K
authors.initials: K
authors.lastname: Takahashi
mesh_terms: D000595:Amino Acid Sequence; D015683:Gene Products, gag / Q000737:chemistry; D016333:HIV Protease / Q000378:metabolism* / Q000648:ultrastructure; D017320:HIV Protease Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007328:Insulin / Q000737:chemistry; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D015394:Molecular Structure; D008970:Molecular Weight; D010455:Peptides / Q000737:chemistry; D013379:Substrate Specificity; D000511:alpha-Macroglobulins / Q000737:chemistry / Q000494:pharmacology* / Q000648:ultrastructure
chemical_list: D015683:Gene Products, gag; D017320:HIV Protease Inhibitors; D007328:Insulin; D010455:Peptides; D000511:alpha-Macroglobulins; D016333:HIV Protease