Document 0924
 DOCN  M9440924
 TI    Steady-state kinetic studies with the polysulfonate U-9843, an HIV
       reverse transcriptase inhibitor.
 DT    9404
 AU    Althaus IW; Chou JJ; Gonzales AJ; LeMay RJ; Deibel MR; Chou KC; Kezdy
       FJ; Romero DL; Thomas RC; Aristoff PA; et al; Upjohn Company, Kalamazoo,
       Michigan 49001.
 SO    Experientia. 1994 Jan 15;50(1):23-8. Unique Identifier : AIDSLINE
       MED/94123748
 AB    The tetramer of ethylenesulfonic acid (U-9843) is a potent inhibitor of
       HIV-1 RT* and possesses excellent antiviral activity at nontoxic doses
       in HIV-1 infected lymphocytes grown in tissue culture. Kinetic studies
       of the HIV-1 RT-catalyzed RNA-directed DNA polymerase activity were
       carried out in order to determine if the inhibitor interacts with the
       template primer or the deoxyribonucleotide triphosphate (dNTP) binding
       sites of the polymerase. Michaelis-Menten kinetics, which are based on
       the establishment of a rapid equilibrium between the enzyme and its
       substrates, proved inadequate for the analysis of the experimental data.
       The data were thus analyzed using steady-state Briggs-Haldane kinetics
       assuming that the template: primer binds to the enzyme first, followed
       by the binding of the dNTP and that the polymerase is a processive
       enzyme. Based on these assumptions, a velocity equation was derived
       which allows the calculation of all the specific forward and backward
       rate constants for the reactions occurring between the enzyme, its
       substrates and the inhibitor. The calculated rate constants are in
       agreement with this model and the results indicated that U-9843 acts as
       a noncompetitive inhibitor with respect to both the template:primer and
       dNTP binding sites. Hence, U-9843 exhibits the same binding affinity for
       the free enzyme as for the enzyme-substrate complexes and must inhibit
       the RT polymerase by interacting with a site distinct from the substrate
       binding sites. Thus, U-9843 appears to impair an event occurring after
       the formation of the enzyme-substrate complexes, which involves either
       an event leading up to the formation of the phosphoester bond, the
       formation of the ester bond itself or translocation of the enzyme
       relative to its template:primer following the formation of the ester
       bond.
 DE    Binding Sites  DNA Polymerases/METABOLISM  DNA Primers/METABOLISM
       HIV-1/DRUG EFFECTS/*ENZYMOLOGY/GENETICS  Kinetics
       Polydeoxyribonucleotides/*BIOSYNTHESIS  Polyethylenes/*PHARMACOLOGY
       Reverse Transcriptase/*ANTAGONISTS & INHIB/METABOLISM  Templates
       JOURNAL ARTICLE

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