ABSTRACT
<p><b>OBJECTIVE</b>To observe the ability of triple helix-forming oligonucleotides (TFO) modified with manganese porphyrin to combine with and cleave HBV DNA fractions.</p><p><b>METHODS</b>The ends of TFO were modified with manganese porphyrin and acridine; At 37 degrees C and pH 7.4 condition in vitro, TFO modified with manganese porphyrin and acridine were bound with 32P labeled HBV DNA fragments, the affinity and specificity binding to target sequence were tested by electrophoretic mobility shift and DNase 1 footprinting assays, the ability to cleave HBV DNA fractions was observed with cleavage experiments.</p><p><b>RESULTS</b>TFO modified with manganese porphyrin and acridine could bind to target sequence in a sequence-dependent manner with Kd values of 3.5 x 10(-7) mol/L and a relative affinity of 0.008. In the presence of KHSO5, TFO modified with manganese porphyrin and acridine could cleave target sequence in the region forming triple DNA.</p><p><b>CONCLUSION</b>In the presence of KHSO5, TFO modified with manganese porphyrin and acridine could cleave target HBV-DNA in sequence-dependent manner.</p>