Large scale expression and purification of recombinant HIV-1 proteinase from Escherichia coli

Screening for HIV protease inhibitors by protection against activity-mediated cytotoxicity in Escherichia coli

Expressed retroviral proteases are often cytotoxic to the hosts. The cytotoxicity of a tethered dimer HIV protease described previously is particularly severe that transformed Escherichia coli cells could not survive the bactericidal activity of the low-level protease produced under uninduced conditions. The presence of HIV protease inhibitors protected the transformed cells from cytotoxic effects and allowed the growth of these cells on plates and in broth. A high throughput screening method was developed to seek compounds that served as "growth factors" for the HIV protease restricted cells. Several compounds identified by this screening supported the growth of these cells, preserved their viability, and inhibited HIV protease. This assay could be used as a general method for screening for inhibitors of recombinant enzymes that produce a cytotoxic phenotype in host cells.

Recombinant protein production via fed-batch culture of the yeast Saccharomyces cerevisiae

Protein production with the recombinant yeast Saccharomyces cerevisiae in fed-batch culture is investigated in this work using beta-galactosidase as a model protein. Segregational instability was negligible during the observed culture periods. The final volumetric productivity, as determined by both cell concentration and gene expression, was strongly affected by the time course of the glucose levels in the bioreactor. It was found that an average glucose feed rate of 1.31 g glucose h-1 resulted in both the maximum beta-galactosidase production rate of 831-950 units ml-1 h-1 and the maximum cell production rate of 0.520-0.524 mg ml-1 h-1.