Hi Irena. Previously, hOGG1 enzymes from Trevigen (cat. No. 4130-100-EB) and NEB (cat. No. M0241) were used in the comet assay; however, they were recently discontinued. It is uncertain if they will be made available again and we negotiate with Trevigen and NEB for a re-supply. Alternative suppliers could be Prospec (cat. No. ENZ-253) or Abbexa (cat. No. abx073274), but these sources of hOGG1 still need to be tested for their enzyme activity in the comet assay. If you have any further questions, do not hesitate to ask us. Sona Vodenkova & Sabine Langie & Amaya Azqueta