Methyl alpha-D-glucopyranoside enhances the enzymatic activity of recombinant beta-galactosidase inclusion bodies in the araBAD promoter system of Escherichia coli

β-galactosidase-catalyzed synthesis of galactosyl chlorphenesin and its characterization

We synthesized galactosyl chlorphenesin (CPN-G) using β-gal-containing Escherichia coli (E. coli) cells in which the conversion yield of chlorphenesin (CPN) to CPN-G reached about 64 % during 12 h. CPN-G was identified and characterized using high-performance liquid chromatography, liquid chromatography-mass spectrometry, Fourier transform-infrared spectrometry, and nuclear magnetic resonance analysis ((1)H and (13)C). We verified that a galactose was covalently bound to a CPN alcohol group during CPN-G synthesis throughout these analyses. In particular, by the hydrolysis of CPN-G using β-gal, it was confirmed that a galactose was bound to CPN. The minimal inhibitory concentration (MIC) results showed that the CPN-G MICs were fairly similar to those of CPN. HACAT cell viability was significantly higher in CPN-G-treated cells than in CPN-treated cells at concentrations of 0.0-20.0 mM. Finally, we accomplished the synthesis of less toxic CPN-G, compared with CPN, using β-gal-containing E. coli cells as whole cells without changes in the MICs against microorganisms.

Learning about protein solubility from bacterial inclusion bodies

The progressive solving of the conformation of aggregated proteins and the conceptual understanding of the biology of inclusion bodies in recombinant bacteria is providing exciting insights on protein folding and quality. Interestingly, newest data also show an unexpected functional and structural complexity of soluble recombinant protein species and picture the whole bacterial cell factory scenario as more intricate than formerly believed.

Improving the yield of soluble 6xHis-tagged interferon-alpha via the addition of repressor of the araBAD promoter system in Escherichia coli

The inhibition of inclusion body formation in Escherichia coli by the addition of alpha-D-glucopyranoside or D-fucose after induction improved the purification yield of soluble recombinant interferon-alpha. When D-fucose was added after induction, more soluble 6xHis-tagged interferon-alpha could be purified compared to when methyl alpha-D-glucopyranoside was added. It was shown that, on the basis of 1 mg dry cell weight, 16.6 microg of soluble 6xHis-tagged interferon-alpha was purified when D-fucose was added after induction and 6 ml nickel-chelated agarose gel column was used. This was about 15 times greater than when induction only was performed and 1 ml nickel-chelated agarose gel was used.