title: Molecular recognition of cyclic urea HIV-1 protease inhibitors.
abstract: As long as the threat of human immunodeficiency virus (HIV) protease drug resistance still exists, there will be a need for more potent antiretroviral agents. We have therefore determined the crystal structures of HIV-1 protease in complex with six cyclic urea inhibitors: XK216, XK263, DMP323, DMP450, XV638, and SD146, in an attempt to identify 1) the key interactions responsible for their high potency and 2) new interactions that might improve their therapeutic benefit. The structures reveal that the preorganized, C2 symmetric scaffolds of the inhibitors are anchored in the active site of the protease by six hydrogen bonds and that their P1 and P2 substituents participate in extensive van der Waals interactions and hydrogen bonds. Because all of our inhibitors possess benzyl groups at P1 and P1', their relative binding affinities are modulated by the extent of their P2 interactions, e.g. XK216, the least potent inhibitor (Ki (inhibition constant) = 4.70 nM), possesses the smallest P2 and the lowest number of P2-S2 interactions; whereas SD146, the most potent inhibitor (Ki = 0.02 nM), contains a benzimidazolylbenzamide at P2 and participates in fourteen hydrogen bonds and approximately 200 van der Waals interactions. This analysis identifies the strongest interactions between the protease and the inhibitors, suggests ways to improve potency by building into the S2 subsite, and reveals how conformational changes and unique features of the viral protease increase the binding affinity of HIV protease inhibitors.
authors.affiliation: DuPont Merck Pharmaceutical Company, Experimental Station, Wilmington, Delaware 19880, USA.
authors.forename: P J
authors.initials: PJ
authors.lastname: Ala
authors.forename: R J
authors.initials: RJ
authors.lastname: DeLoskey
authors.forename: E E
authors.initials: EE
authors.lastname: Huston
authors.forename: P K
authors.initials: PK
authors.lastname: Jadhav
authors.forename: P Y
authors.initials: PY
authors.lastname: Lam
authors.forename: C J
authors.initials: CJ
authors.lastname: Eyermann
authors.forename: C N
authors.initials: CN
authors.lastname: Hodge
authors.forename: M C
authors.initials: MC
authors.lastname: Schadt
authors.forename: F A
authors.initials: FA
authors.lastname: Lewandowski
authors.forename: P C
authors.initials: PC
authors.lastname: Weber
authors.forename: D D
authors.initials: DD
authors.lastname: McCabe
authors.forename: J L
authors.initials: JL
authors.lastname: Duke
authors.forename: C H
authors.initials: CH
authors.lastname: Chang
mesh_terms: D019380:Anti-HIV Agents / Q000737:chemistry*; D001381:Azepines / Q000737:chemistry; D016333:HIV Protease / Q000737:chemistry*; D017320:HIV Protease Inhibitors / Q000737:chemistry*; D015497:HIV-1 / Q000201:enzymology; D006860:Hydrogen Bonding; D008968:Molecular Conformation; D014508:Urea / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology
chemical_list: D019380:Anti-HIV Agents; D001381:Azepines; D017320:HIV Protease Inhibitors; C112386:SD 146 cyclic urea; C112387:XK 216; C104713:XK 263; C112388:XV 638; D014508:Urea; D016333:HIV Protease; C085816:DMP 323; C099851:DMP 450