B IO C H E M IS T R Y PE A R L S
The quinolone antibiotics target bacterial DNA gyrase in many
Supercoiling is controlled by topoisomerases which alter the topol-
ogy of the circular DNA but not its covalent structure.
Type I topoisomerases relax DNA from negative supercoils
formed by the action of type II topoisomerase by creating tran-
sient single-strand breaks in DNA.
Type II topoisomerases (also called DNA gyrases) change DNA
topology by making transient double-strand breaks in DNA.
Histones are abundant proteins associated with eukaryotic DNA and
are a family of basic proteins rich in the positively charged amino
acids lysine and/or arginine, which interact with the negative
charges of DNA.
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