FAQ: Is the linking number (ΔLk) or the superhelical density (σ) that results from the gyrase reaction fixed or random? Does the sequence, GC content or size of the circular DNA affect the linking number?

The resulting linking number is neither random nor fixed. There is a distribution of molecules of differing numbers of twists, based around a mean number. This value could vary based on factors, such as pH, temperature, ionic strength, sequence, length, cruciform formation, etc.