DNA gyrase: an enzyme that introduces superhelical turns into DNA.

TLDR

DNA gyrase converts relaxed closed‑circular DNA into negatively supercoiled DNA. The gyrase reaction requires ATP and Mg²⁺ and is stimulated by spermidine. The purified E.

Abstract

Relaxed closed-circular DNA is converted to negatively supercoiled DNA by DNA gyrase. This enzyme has been purified from Escherichia coli cells. The reaction requires ATP and Mg++ and is stimulated by spermidine. The enzyme acts equally well on relaxed closed-circular colicin E1, phage lambda, and simian virus 40 DNA. The final superhelix density of the DNA can be considerably greater than that found in intracellularly supercoiled DNA.