BIOCHEMICAL ACTIVITIES OF DENATURED COVALENTLY CLOSED CIRCULAR DUPLEXDNA

Covalently closed circular duplex DNA when exposed to high alkaline pH followed by neutralization yields a collapsed state structure (form I (d) that can undergo transition to form I and was susceptible to S1 nu clease. Form I(d), in spite of its compact structure, admits specific cleavage by restriction enzymes over its entire genome. When used in a semi-in vitro replication complex, form I(d) gave significantly bette r template activity, and undergoes better primer extension in in vitro using Klenow. Thus form I(d) having a compact shape can behave as a b etter substrate in a few key enzymatic reactions.