       Document 0004
 DOCN  M9610004
 TI    Removal of anti-human immunodeficiency virus 2',3'-dideoxynucleoside
       monophosphates from DNA by a novel human cytosolic 3'-->5' exonuclease.
 DT    9601
 AU    Skalski V; Liu SH; Cheng YC; Department of Pharmacology, Yale University
       School of Medicine,; New Haven, CT 06510, USA.
 SO    Biochem Pharmacol. 1995 Sep 7;50(6):815-21. Unique Identifier : AIDSLINE
       MED/96021080
 AB    A 3'-->5' exonuclease has been highly purified from the cytosol of human
       acute lymphoblastic leukemia H9 cells. The apparent molecular weight of
       this enzyme was approximately 50,000, as indicated by its sedimentation
       in glycerol gradients. The exonuclease did not copurify with DNA
       polymerase activity, required MgCl2 for its exonucleolytic activity, and
       was inhibited by KCl above 60 mM. The enzyme was active on
       single-stranded DNA, DNA duplexes and DNA/RNA duplexes, and it was
       efficient at removing 3'-terminal mispairs from DNA. The products of the
       exonucleolytic reaction were deoxynucleoside 5'-monophosphates. The
       behavior of the exonuclease was examined on DNA terminated at the 3' end
       with a variety of dideoxynucleosides that are potent against human
       immunodeficiency virus type 1. The exonuclease has a broad substrate
       specificity; however, the rate of the enzymatic reaction varied among
       the D dideoxynucleosides tested (ddAMP = ddCMP > d4TMP > AZTMP).
       Similarly, the enzyme was examined for its reactivity with DNA
       terminated by either the D or L enantiomers of ddC, SddC or FddC. The
       removal of analogs with the native D configuration was at least 6-fold
       more rapid than that of the L-compounds, and the type of structural
       modification had an impact on the rate at which the D enantiomers were
       removed (SddCMP > ddCMP > FddCMP). The monophosphate forms of AZT, D4T,
       L-FddC and L-ddC were potent inhibitors of the exonuclease at micromolar
       concentrations, while D-ddCMP partially inhibited the enzyme at
       millimolar concentrations. Based on its physical and enzymatic
       properties, this exonuclease represents a novel enzyme that may have an
       important role in determining the relative potencies of
       dideoxynucleosides against human immunodeficiency virus type 1.
 DE    Antiviral Agents/*METABOLISM/PHARMACOLOGY  Base Sequence  Cell Line
       Comparative Study  Cytosol/*ENZYMOLOGY
       Dideoxynucleosides/*METABOLISM/PHARMACOLOGY  DNA,
       Single-Stranded/*METABOLISM  Exonucleases/CHEMISTRY/ISOLATION &
       PURIF/*METABOLISM  Human  HIV-1/*DRUG EFFECTS/METABOLISM  Molecular
       Sequence Data  Phosphates/METABOLISM  Stavudine/METABOLISM
       Stereoisomers  Substrate Specificity  Support, U.S. Gov't, P.H.S.  Virus
       Replication/DRUG EFFECTS  Zalcitabine/ANALOGS & DERIVATIVES/METABOLISM
       Zidovudine/METABOLISM  JOURNAL ARTICLE

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

