Nucleic Acids Research, 1981, Vol. 9, No. 22 6083-6092
© 1981
ENZYMOLOGY |
Selective inhibition by harmane of the apurinic/apyrimidinic endonuclease activity of phage T4-induced UV endonuclease
Department of Biochemistry, University of Minnesota St. Paul, MN 55108 Department of Biochemistry, University of California Berkeley, CA 94720, USA
Received September 16, 1981. 1-Methyl-9H-pyrido-[3,4-b]indole (harmane) inhibits the apurinic/apyrimidinic (AP) endonuclease activity of the UV endonuclease induced by phage T4, whereas it stimulates the pyrimidine dimer-DNA glycosylase activity of that enzyme. E. coli endonuclease IV, E. coli endonuclease VI (the AP endonuclease activity associated with E. coli exonuclease III), and E. coli uracil-DNA glycosylase were not inhibited by harmane. Human fibroblast AP endonucleases I and II also were only slightly inhibited. Therefore, harmane is neither a general inhibitor of AP endonucleases, nor a general inhibitor of Class I AP endonucleases which incise DMA on the 3'-side of AP sites . However, E. coli endonuclease III and its associated dihydroxythymine-DNA glycosylase activity were both inhibited by harmane. This observation suggests that harmane may inhibit only AP endonucleases which have associated glycosylase activities.