Glutathione peroxidase（GPX） plays an important role in scavenging reactive oxygen species. A series of catalytic antibodies with GPX activity have been generated by the authors of＇ this study. To obtain humanized catalytic antibodies, the phage-displayed human antibody library was used to select novel antibodies by repetitive screening, Phage antibodies, scFv-B8 and scFv-H6 with the GSH-binding site, were obtained from the library by enzyme-linked immu- nosorbent assay（ELISA） analysis with 4 rounds of scelection against their respective haptens, S-2,4-dinitriphenyl t-butyl ester（GStI-s-DNP-Bu） and S-2,4-dinit,-iphenyl t-hexyl ester（GSH-s-I）NP-He）. Nevertheless, several studies need to be condueted to determine whether scFv-B8 and seFv-tI6 possess GPX activity. 1＇o enhance the speed of the selection, selenocysteine（Sec, the catalytic group of GPX） was incorporated directly into the phages, scFv-B8 and seFv-H6, by chemical mutation to form the phages Se-scFv-B8 and Se-scFv-H6. The GPX activities were found to be 3012 units/μmol and 2102 units/μmol, respectively. To improve the GPX activity of the phage Se-scFv-B8, DNA shuffling was used to construct a secondary library and another positive phage antibody scFv-B9 was screened out by another panning against GSH-s-DNP-Bu. When Sec was incorporated via chemical mutation into the phage antibody scFv-B9, its GPX activity reached 3560 units/μmol, which is 1.17-fold higher than the phage antibody Se-scFv-B8 and almost approached the order of magnitude of native GPX. The rapid selection is the prerequisite for generating humanized Se-seFv with GPX activity.
LIN FengLI YingYANG Wen-kuiLIANG BingMU YingSUN YeLI WeiLUO Gui-min
