ABSTRACT
Midkine is a heparin-binding growth factor, which plays important roles in the regulation of cell growth and differentiation. The non-tagged recombinant human midkine (rhMK) is therefore required to facilitate its functional studies of this important growth factor. In the present work, rhMK was expressed in Escherichia coli (E. coli) BL21 (DE3). The expression of midkine was efficiently induced by isopropyl-beta-D-thiogalactopyranoside (IPTG). After sonication, midkine was recovered in an insoluble form, and was dissolved in guanidine hydrochloride buffer. Renaturation of the denatured protein was carried out in the defined protein refolding buffer, and the refolded protein was purified using S-Sepharose ion-exchange chromatography. The final preparation of the rhMK was greater than 98% pure as measured by sodium dodecylsulfate-polyacrylamid gel electrophoresis (SDS-PAGE) and reverse phase high performance liquid chromatography (RP-HPLC). The purified rhMK enhanced the proliferation of NIH3T3 cells.
Subject(s)
Animals , Humans , Mice , Base Sequence , Cell Proliferation , Cytokines , Genetics , Pharmacology , Escherichia coli , Genetics , Molecular Sequence Data , NIH 3T3 Cells , Recombinant ProteinsABSTRACT
Halomonas sp.BYS-1 was a moderately halophilic bacteria strain isolated from activated sludge,It could grow on MM with NaCl concentration from 0.1～2.6 mol/L and phenyl acetic acid as sole carbon souce. When BYS-1 grew in the media with different concentrations of NaCl, there was no obvious change in its intracellular Na+ contents , it accumulated K+, glutamic acid and betaine as osmoprotectants. Its intracellular contents of K+,glutamic acid and betaine increased by 1.9,2.4 and 13.6 times, respectively, when the concentration of NaCl increased from 0.1 mol/L to 2mol/L.