A new human catalytic antibody Se-scFv-2D8 and its selenium-containing single domains with high GPX activity

Glutathione peroxidase (GPX) is a well-known antioxidant selenoenzyme, which can catalyze the reduction of a variety of hydroperoxides and consequently protect cells and other biological tissues against oxidative damage. Many attempts have been made to mimic its function, and a human catalytic antibody Se-scFv-B3 with GPX activity has been prepared in our previous study. This time, a new clone 2D8 that bound specifically to the glutathione analog GSH-S-DNPBu was selected again by using the technology of phage display antibody library, and then scFv-2D8 was successfully expressed in soluble form and purified using Ni²⁺-immobilized metal affinity chromatography. After being converted into selenium-containing scFv by chemically modification, it showed higher GPX activity than previous abzyme Se-scFv-B3. The heavy chain variable fragment of scFv-2D8 was also prepared and converted into selenium-containing protein using the same method. This selenium-containing single-domain antibody showed some GPX activity and, to the best of our knowledge, is the first human single-domain abzyme with GPX activity, which lays a foundation for preparing GPX abzyme with human origin, lower molecular weight and higher activity.