Bacillus anthracis protective antigen (PA) is a well known and relevant immunogenic protein that is the basis for both anthrax vaccines and diagnostic methods. Properly folded antigenic PA is necessary for these applications. In this study a high level of PA was obtained in recombinant Escherichia coli. The protein was initially accumulated in inclusion bodies, which facilitated its efficient p...

Background: Streptavidin is a protein produced by Streptomyces avidinii with strong biotin-binding ability. The non-covalent, yet strong bond between these two molecules has made it a preferable option in biological detection systems. Due to its extensive use, considerable attention is focused on streptavidin production by recombinant methods. Methods: In this study, streptavidin was express...

Density is an easily adjusted variable in molecular dynamics (MD) simulations. Thus, pressure-jump (P-jump)-induced protein refolding, if it could be made fast enough, would be ideally suited for comparison with MD. Although pressure denaturation perturbs secondary structure less than temperature denaturation, protein refolding after a fast P-jump is not necessarily faster than that after a tem...

The fast reaction ((T2) approximately 50 msec) observed previously in the refolding of thermally unfolded ribonuclease A (disulfide bonds intact) has now been studied by two properties indicative of enzyme function: binding of a competitive inhibitor (2'CMP) and hydrolysis of a substrate (CpA --> C > p + A). Both the binding and catalytic reactions are fast (<2 msec) compared to refolding. Bind...

Proteins that are modified by chemical conjugation require at least two separate purification processes. First the bulk protein is purified, and then after chemical conjugation, a second purification process is required to obtain the modified protein. In an effort to develop new enabling technologies to integrate bioprocessing and protein modification, we describe the use of disulfide-bridging ...

In vitro, small Hsps (heat-shock proteins) have been shown to have chaperone function capable of keeping unfolded proteins in a form competent for Hsp70-dependent refolding. However, this has never been confirmed in living mammalian cells. In the present study, we show that Hsp27 (HspB1) translocates into the nucleus upon heat shock, where it forms granules that co-localize with IGCs (interchro...

Refolding of proteins at high concentrations often results in aggregation. To gain insight into the molecular aspects of refolding and to improve the yield of active protein, we have studied the refolding of lysozyme either from its denatured state or from its denatured/reduced state. Refolding of denatured lysozyme, even at 1 mg/ml, yields fully active enzyme without aggregation. However, refo...