A A closed circular DNA that is 720 base pairs If the origin

A. A closed circular DNA that is 720 base pairs.

If the original DNA shown in part A is treated with Topoisomerase II from E. coli in the presence of ATP, what would be the new values of L, T and W. Assume te Topoimerase only does one catalytic cyle.

Solution

Negatively super coiled DNA contains more bases per turn. Super coiling is assessed by linking number (L) .

L = T+ W

Linking number = Twisting number + writhing number

L = 10

T = 10 turns

bases / turn = 720 / 10 = 72

W = -1