[Efficient purification of recombinant human NDPK-A in pilot-scale]

To purify recombinant human nucleoside diphosphate kinase A (rhNDPK-A) efficiently in pilot scale, cells of rhNDPK-A producing E. coli were homogenized by high pressure under 4 degrees C, 950 Pa. The insoluble debris was removed by microfiltration and the soluble portion was concentrated by ultrafiltration. The resulted crude sample was loaded on DEAE-sepharose Fast Flow. The target fraction was collected and then load on Cibacron Blue 3GA Sepharose CL-4B. Eluted with buffer containing ATP from the AC column, rhNDPK-A was polished with ultrafiltration. The results showed that after homogenized 2 rounds, 1500g cells of E. coli brought crude sample containing 47.6g NDPK-A. Treated with microfiltration and ultrafiltration, 27.3g of NDPK-A were recovered from this bacteria homogenate. After 2-step purification with column chromatography and then polished with ultrafiltration, 17.2 g rhNDPK-A were collected with purity of 96.3%. The recovery of the whole purification process was 36.2%, and the productivity of rhNDPK-A was 1.15 g per 100 g wet cells. Comparing the recovery of each purification step, it was found that the recovery of polish is higher than that of affinity chromatography, which is higher than that of ion exchange chromatography. The limit step was the process of sample pretreatment among the 4 purification steps. Combine with the fermentation results reported before, it was deduced that the productivity of rhNDPK-A was 510 mg/L. In conclusion, an easily controlled purification condition with high yield provides material for the translation researches of NDPK; In addition, it was suggested the crucial step determine the recovery of non-secretive recombinant proteins might be the process of sample pretreatment, not be the process of column chromatography.