Abstract: To identify the3D structure and physical and chemical character of a single-chain Fv against HBsAg （HBscFv）‚methods of experimental biology and computational biology were applied．First‚Antheprot‚a comprehensive software to analyze protein‚was used to predict the isoelectric point （pI） of HBscFv．Second‚the predicted result was confirmed by IEF．Third‚neural network systems （PHDsec） and SWISS-MODEL were applied to predict the secondary and tertiary structure of HBscFv‚respectively．It was found that the theoretical pI of HBscFv is8．51and the experimental pI is from7．3to8．1． PHDsec indicated that HBscFv is a whole β-globin．The predicted tertiary structure displayed that the VH domain of HBscFv was made up of9β-sheets and VL domain of8β-sheets．Due to the specific characteristics of single-chain Fv‚SWISS-MODEL software for homo-logy modeling of tertiary structure cannot predict the quaternary structure resulting from the interaction of VH and VL domains．

Key words: HBsAg, single-chain Fv, isoelectric point, structure prediction, recombinant human antibody