We offer a range of gel-based assays and have many years experience working with customers from both pharmaceutical companies and with academics.
These all separate the products of the reactions from the substrate using agarose gels. Supercoiling and relaxation reactions are performed in tubes and then the products separated using agarose gels. The separation allows the different topoisomerase intermediates to be seen as well as the supercoiled and relaxed plasmids.
Decatenation reactions measure the unlinking of DNA mini-circles from a complex of mini- and maxi-circles in kDNA, which has been isolated from Crithidia fascicula. Some enzymes have higher activities in decatenation compared to relaxation reactions.
The visual nature of the results from gel-based assays can provide more information about the reactions than microtitre plate-based assays. They can be used for screening compounds for activity as well as determination of IC50 values.
Cleavage of DNA is an essential part of the topoisomerase reaction mechanism and stabilisation of cleavage complexes is the key to the activity of many inhibitors such as the quinolones and etoposide. Cleavage assays can be used to determine the activity of compounds in stabilising cleavage complexes.
DNA unwinding assays can be used to determine if a compound is an intercalator.
Whatever the assays you need to be performed, we will carry them out and provide a report including the gel results and any IC50 values.