Refolding by High Pressure of a Toxin Containing Seven Disulfide Bonds: Bothropstoxin-1 from Bothrops jararacussu

Aggregation is a serious obstacle for recovery of biologically active heterologous proteins from inclusion bodies (IBs) produced by recombinant bacteria. E. coli transformed with a vector containing the cDNA for Bothropstoxin-1 (BthTx-1) expressed the recombinant product as IBs. In order to obtain the native toxin, insoluble and aggregated protein was refolded using high hydrostatic pressure (HHP). IBs were dissolved and refolded (2 kbar, 16 h), and the effects of protein concentration, as well as changes in ratio and concentration of oxido-shuffling reagents, guanidine hydrochloride (GdnHCl), and pH in the refolding buffer, were assayed. A 32% yield (7.6 mg per liter of bacterial culture) in refolding of the native BthTx-1 was obtained using optimal conditions of the refolding buffer (Tris–HCl buffer, pH 7.5, containing 3 mM of a 2:3 ratio of GSH/GSSG, and 1 M GdnHCl). Scanning electron microscopy (SEM) showed that that disaggregation of part of IBs particles occurred upon compression and that the morphology of the remaining IBs, spherical particles, was not substantially altered. Dose-dependent cytotoxic activity of high-pressure refolded BthTx-1 was shown in C2C12 muscle cells

Protein refolding at high pressure: Optimization using eGFP as a model

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Refolding of a mutant form of green fluorescent protein (eGFP), which only emits characteristic fluorescence when in the natively folded state, was accomplished under high hydrostatic pressure (HHP). Compression of eGFP inclusion bodies (IB) at 2.40 kbar for 30 min dissociated most of the aggregates and reduced the quantity of IBs. However, fluorescence at 509 nm indicated that eGFP did not refold under this condition. The refolding process was evaluated under various decompression conditions, following IB dissociation at 2.40 kbar. During stepwise decompression, increases in fluorescence were obtained at pressures ranging between 1.38 kbar and atmospheric pressure. The highest levels of eGFP refolding were achieved by incubation at pressure levels between 0.35 and 0.69 kbar in the absence of chaotropic reagents. The refolding was abolished when HHP was applied in the presence of 0.5-1.5 M GdnHCl. Our approach focused on monitoring the bioactivity of the recombinant protein, i.e., fluorescence, instead of solubility, which is not an ideal indicator of proper refolding. The higher yields of a bioactive product by incubation at pressure levels of 0.35-0.69 kbar without using chaotropic salts improve upon the HHP-refolding methods that have been previously described. (C) 2010 Elsevier Ltd. All rights reserved.462512518Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPESP [07/54624-4]CNPq [479816/2007-7

The inflammatory conundrum - where exactly do we stand?

Schistosomiasis, caused mainly by S. mansoni, S. haematobium and S. japonicum, continues to be a serious tropical disease and public health problem resulting in an unacceptably high level of morbidity in countries where it is endemic. Praziquantel, the only drug currently available for treatment, is unable to kill developing schistosomes, it does not prevent re-infection and its continued extensive use may result in the future emergence of drug-resistant parasites. This scenario provides impetus for the development and deployment of anti-schistosome vaccines to be used as part of an integrated approach for the prevention, control and eventual elimination of schistosomiasis. This review considers the present status of candidate vaccines for schistosomiasis, and provides some insight on future vaccine discovery and design