Objective: To obtain recombinant human SDF-1β expressed in E. coli and purify SDF-lfi with bio-logical activity from the bacterium. Methods: A thioredoxin-SDF-1β fusion protein (26×103) composed of230 amino acid residues was expressed in E. coli AD494 (DE3)pLysS under the induction of IPTG whenpET32a( + )-SDF-1β was used as an expression vector. Purified SDF-lfi was produced through following pro-cedures: Bacteria lysis, metal-chelated affinity chromatography (MAC), enterokinase digestion to separateSDF-lfi from fusion protein, cation exchange chromatography (CEC) and reverse-phase high performance liq-uid chromatography (RP-HPLC). Western blot with anti-SDF-1β monoclonal antibody (mAb), N-terminalamino acid sequencing, ligand-binding assay and cytosensor/microphysiometry were used to investigate thebiochemical characters and biological activities of the purified SDF-1β. Results: From 10% to 15% of totalbacterium protein was expressed as fusion protein. Approximately 400 fig purified SDF-1β (7. 8? Objective: To obtain recombinant human SDF-1β expressed in E. coli and purify SDF-lfi with bio-logical activity from the bacterium. Methods: A thioredoxin-SDF-1β fusion protein (26 × 103) composed of230 amino acid residues was expressed in E. coli AD494 (DE3) pLysS under the induction of IPTG whenpET32a (+) - SDF-1β was used as an expression vector. Purified SDF-lfi was produced through the following pro- cedures: Bacteria lysis, metal- chelated affinity chromatography MAC), enterokinase digestion to separate SDF-lfi from fusion protein, cation exchange chromatography (CEC) and reverse-phase high performance liq-uid chromatography (RP-HPLC) -terminalamino acid sequencing, ligand-binding assay and cytosensor / microphysiometry were used to investigate thebiochemical characters and biological activities of the purified SDF-1β. Results: From 10% to 15% of totalbacterium protein was expressed as fusion protein. Approximately 400 fig puri fied SDF-1β (7.8?