Abstract: BACKGROUND ＆ AIM: To gain the NGAL protein with definite abundance and purity at last by the novel oncogene NGAL fusion expression in prokarote , purification by Ni2＋- metal chelate affinity chromatography and identification by MALDI－TOF－MS of its expression production. MATERIAL AND METHODS: pDsbA 2.0－NGAL fusion expression vector was transformed to E.coli,induced to express with IPTG and productivity as well as solubility of the expressed production were analyzed via SDS－PAGE. Then expressed production was purified by Ni2＋-metal chelate affinity chromatography and identification by MALDI－TOF－MS. RESULTS: After induced expression of pDsbA2.0－NGAL fusion expression vector with IPTG, SDS－PAGE analysis presented the expressed NGAL fusion protein was high productivity with good solubility. The purity of expressed NGAL protein was more than 95 ％ after purified by Ni2＋- metal chelate affinity chromatography and identification by MALDI－TOF－MS indicated that the molecular weight error was only 0.91 ‰ between the purified NGAL protein and its theoretical one. CONCLUSION: By the novel oncogene NGAL fusion expression in prokarote, purification by Ni2＋- metal chelate affinity chromatography and identification by MALDI－TOF－MS of its expression production, NGAL protein with definite abundance and electrophoresis purity was truely gained at last, which built up a good experimental material for the preparation of its antibody.

Key words: NGAL, Ni2＋-metal chelate affinity chromatography, 6×His, MALDI－TOF－MS