title: High-level expression in Escherichia coli and purification of the membrane-bound form of cytochrome b(5).
abstract: Expression of the membrane-bound form of rabbit cytochrome b(5) in Escherichia coli has been significantly improved through the use of the T7 expression vector pLW01 (A. Bridges, L. Gruenke, Y.-T. Chang, I. Vakser, G. Loew, and L. Waskell, 1998, J. Biol. Chem. 273, 17036-17049) in conjunction with strain C41(DE3) (B. Miroux and J. Walker, 1996, J. Mol. Biol. 260, 289-298). Cell cultures expressing the cytochrome b(5) contained an average of 820 mg/liter of culture and reached peak levels as high as 1100 mg/liter when higher antibiotic concentrations were used. Maximal levels were obtained from cultures when expression was induced with 10 microM IPTG. Approximately 90% of the cytochrome b(5) was expressed as apoprotein which was reconstituted by addition of exogenous heme. The cytochrome b(5) was purified from detergent-solubilized bacterial membranes using anion-exchange chromatography on DEAE-Sepharose followed by size-exclusion chromatography on Superdex-75. Purification of cytochrome b(5) from a 500-ml culture yielded 121 mg of protein which had a specific content of 50 nmol of heme per milligram of protein with an overall recovery of 35%. The final cytochrome b(5) was free of any detectable contaminants when analyzed by SDS-PAGE.
authors.affiliation: Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109-0606, USA.
authors.forename: S B
authors.initials: SB
authors.lastname: Mulrooney
authors.forename: L
authors.initials: L
authors.lastname: Waskell
mesh_terms: D000818:Animals; D002847:Chromatography, Agarose; D015786:Cytochromes b5 / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D007425:Intracellular Membranes / Q000737:chemistry; D008565:Membrane Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D011817:Rabbits; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D008565:Membrane Proteins; D011994:Recombinant Proteins; D015786:Cytochromes b5