H19 dye is a fluorescence dye specifically designed for high throughput DNA supercoiling and relaxation assays. DNA topoisomerases such as bacterial gyrases convert relaxed DNA into supercoiled DNA (DNA supercoiling reaction).  The reverse reaction that converts supercoiled DNA to relaxed DNA (DNA relaxation reaction) is carried out by DNA topoisomerase I.   The assay principle is based on that the supercoiled DNA and relaxed DNA yield different fluorescent intensity when interact with fluorescence dye H19.  When the relaxed DNA is converted into its supercoiled form, the fluorescent signal increases.  When the supercoiled DNA is converted into its relaxed form, the fluorescent signal decreases. The difference of fluorescence intensity is used to measure the DNA topology changes by various DNA topoisomerases and high throughput screen of topoisomerase inhibitors. The assay is in a 96-well plate format. It can be modified to 384-well plate format.

The H19 Dye for DNA Relaxation and Supercoiling Assays (Catalog No. DSA1000D) includes 57 µl of 4500 x Dye H19 and 26 ml of 10 x H19 dilution buffer.  It is for 1000 assays of DNA relaxation or supercoiling reactions in a 96-well plate format. 

The 10x H19 dilution buffer (Catalog No. H19BUF-10) includes 100 ml of 10 x H19 dilution buffer.