Document 0592
 DOCN  M9460592
 TI    Kinetic and mutational analysis of human immunodeficiency virus type 1
       reverse transcriptase inhibition by inophyllums, a novel class of
       non-nucleoside inhibitors.
 DT    9404
 AU    Taylor PB; Culp JS; Debouck C; Johnson RK; Patil AD; Woolf DJ; Brooks I;
       Hertzberg RP; Department of Biomolecular Discovery, SmithKline Beecham;
       Pharmaceuticals, King of Prussia, Pennsylvania 19406.
 SO    J Biol Chem. 1994 Mar 4;269(9):6325-31. Unique Identifier : AIDSLINE
       MED/94165008
 AB    Inophyllums are novel non-nucleoside inhibitors of human
       immunodeficiency virus (HIV) type 1 reverse transcriptase identified
       through an enzyme screening program and isolated from the plant
       Calophyllum inophyllum. The kinetics of reverse transcriptase inhibition
       by inophyllum B were characterized using recombinant purified enzyme, a
       heteropolymeric RNA template, and a scintillation proximity assay.
       Preincubation of inhibitor with the enzyme-template-primer complex for
       11 min was required for maximal inhibition of reverse transcriptase to
       occur, suggesting that inophyllum B had a slow on-rate and that
       template-primer must bind to reverse transcriptase prior to inhibitor
       binding. Inhibition of reverse transcriptase by inophyllums was shown to
       be reversible. When thymidine triphosphate was the variable substrate,
       inophyllum B inhibited reverse transcriptase noncompetitively with a Ki
       of 42 nM. Enzyme inhibition with respect to template-primer was
       uncompetitive with a Ki of 26 nM. Reverse transcriptase enzymes
       containing point mutations in which tyrosine 181 was changed to either
       cysteine or isoleucine exhibited marginal resistance to inophyllums but
       were resistant to (+)-(5S)-4,5,6,7-tetrahydro-9-chloro-5-methyl-6-
       (3-methyl-2-butenyl)-imidazo[4,5,1-j,k][1,4]benzodiazepin-2-(1H)-- t
       hione (TIBO R82913). A mutant enzyme in which tyrosine 188 was changed
       to leucine was cross-resistant to both inophyllum B and TIBO R82913, as
       was HIV type 2 reverse transcriptase. These studies suggest that
       inophyllum B and TIBO R82913 bind to distinct but overlapping sites.
       Inhibition of avian myeloblastosis virus reverse transcriptase and
       Moloney murine leukemia virus reverse transcriptase by inophyllum B was
       detectible, suggesting that these inhibitors may be more promiscuous
       than other previously described non-nucleoside inhibitors. Inophyllums
       were active against HIV type 1 in cell culture with IC50 values of
       approximately 1.5 microM. These studies imply that the inophyllums have
       a novel mechanism of interaction with reverse transcriptase and as such
       could conceivably play a role in combination therapy.
 DE    Antiviral Agents/*PHARMACOLOGY  Base Sequence
       Benzodiazepines/*PHARMACOLOGY  Comparative Study
       Coumarins/CHEMISTRY/ISOLATION & PURIF/*PHARMACOLOGY  HIV-1/*ENZYMOLOGY
       Imidazoles/*PHARMACOLOGY  Kinetics  Molecular Sequence Data
       *Mutagenesis, Site-Directed  Oligodeoxyribonucleotides  Recombinant
       Proteins/ANTAGONISTS & INHIB/BIOSYNTHESIS/ISOLATION &  PURIF  Reverse
       Transcriptase/*ANTAGONISTS & INHIB/BIOSYNTHESIS/ISOLATION  & PURIF
       Structure-Activity Relationship  Substrate Specificity  Support, U.S.
       Gov't, P.H.S.  JOURNAL ARTICLE

       SOURCE: National Library of Medicine.  NOTICE: This material may be
       protected by Copyright Law (Title 17, U.S.Code).