BIOCHEMICAL-EVIDENCE FOR THE COEXISTENCE OF MONOMORPHIC AND POLYMORPHIC N-ACETYLTRANSFERASE ACTIVITIES ON A COMMON PROTEIN IN RABBIT LIVER

  • 1 January 1982
    • journal article
    • research article
    • Vol. 220  (1) , 1-7
Abstract
New Zealand White rabbits were classified as rapid or slow acetylators by measuring the N-acetylation half-life of i.v. administered sulfadiazine, by pedigree analysis and by determination of liver N-acetyltransferase (NAT) activity in vitro. Slow acetylator rabbits had significantly lower levels of p-aminobenzoic acid [PABA] NAT activity in vitro than did rapid acetylator rabbits, demonstrating genetic covariation of PABA (monomorphic) and isoniazid (polymorphic) NAT activity. Monomorphic and polymorphic NAT activities could not be separated by 2 extensive purification procedures involving sequential centrifugation, fractional precipitation with ammonium sulfate, ion-exchange chromatography on DEAE-cellulose, gel filtration on Sephadex or Sephacryl and isoelectric focusing or electrophoresis on polyacrylamide gels. Indistinguishable heat inactivation patterns were demonstrated for the 2 NAT activities utilizing highly purified NAT preparations at 2 different temperatures. Each of these findings supports the coexistence of monomorphic and polymorphic NAT activities on a common protein.