, Volume 37, Issue 5, pp 609-614

Protein compositional analysis of inclusion bodies produced in recombinant Escherichia coli

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Culture conditions favouring the simulataneous formation of soluble protein and inclusion bodies (IBs) were chosen for producing the cytoplasmic protein β-galactosidase or the periplasmic protein TEM-β-lactomase. Soluble and insoluble cell fractions of Escherichia coli producing either β-galactosidase or TEM-β-lactomase were analyzed by one- and two-dimensional gel electrophoresis and subsequent silver staining or immunodection of the recombinant protein. The results show that truncated fragments of the recombinant protein were not present in the soluble cell fraction but accumulate in the IB fraction. The presense of other cellular, non-plasmid-encoded proteins in IB preparations such as the outer membrane proteins OmpF, OmpC, and OmpA or the ribosomal subunit proteins L7/L12 was attributed to co-precipitation of cell-debris-associated components. Protein-folding enzymes were not detected in IB preprations. The specificity of in-vivo protein association in the formation of IBs and its implication on protein purification is discussed.

Correspondence to: J. E. Bailey