The mechanism of oxidative refolding of proteins was elucidated in more detail from the intensive and extensive studies in the past decades. 1. Most of the proteins examined so far proceed oxidative refolding via multiple pathways rather than a single and specific pathway. This is consistent with the folding energy landscape theory. 2. It is the native interactions rather than the non-native interactions that direct the folding process. This is not necessarily incompatible with the importance of the non-native disulfide intermediates in the bovine pancreatic trypsin inhibitor (BPTI) pathway, which are just a chemical necessity in the intramolecular arrangement to facilitate native disulfide formation. 3. Based on the BPTI refolding it was suggested that disulfide bonds have a stabilizing effect on the native state without determining either the folding pathway or the final three-dimensional structure of the protein. This point of view is not applicable to other proteins. Studies on the refolding of prochymosin unequivocally demonstrated that the formation of native disulfides is the prerequisite to the recovery of the native conformation. It is more likely that the interdependence between the native disulfide formation and the formation of native structure is a general rule. 4. At the early stage of oxidative refolding disulfide formation is essentially a random process, with the progress of refolding further disulfide formation is increasingly dependent on the conformations of the intermediates. Enhancing the renaturation yield of recombinant proteins is a major challenge in biotechnology. In addition to aggregation, the formation of species with mispaired disulfide bonds is a leading cause of decreased yield. Progress in understanding the mechanism of oxidative refolding has provided insight into how to solve this problem. As described above, at the later stage of refolding disulfide formation depends on the conformations of intermediates. The intermediates with native-like and flexible structure favourable for native disulfide formation and correct refolding are productive intermediates, while the unproductive intermediates tend to adopt stable conformations, which render the thiol groups and disulfide bond(s) inaccessible and further folding unfavourable energetically. Therefore, the principle to enhance the renaturation yield of disulfide-containing proteins is to cause the productive intermediates to predominate by destabilizing the unproductive intermediates. To approach this, alkaline pH, low temperature, labilizing agents, protein disulfide isomerase and its analogues and alteration of primary structure have been proved useful to adjusting the structure of the unproductive intermediates so as to facilitate thiol/disulfide interchange and in turn the native disulfide formation. The prospects for the oxidative refolding of proteins both in basic and applied researches are discussed in this review article.
Animals ; Biotechnology ; Disulfides ; chemistry ; Humans ; Oxidation-Reduction ; Protein Folding ; Proteins ; chemistry ; genetics ; metabolism

Algorithms ; Crystallography, X-Ray ; Disulfides ; chemistry ; Models, Molecular ; Protein Conformation ; Proteins ; chemistry

We study the techniques of synthesis of disulfide bond-bearing cyclopeptides FIK. This experimentation with the material of Fmoc-aa use Solid-Phase synthesis after condensation by HBTU/HOBt/DIEA to synthesize linear peptide, then cyclopeptide was synthesized by creation of intramolecular disulfide bond by means of 12 oxidation of bis cysteine sulfhydryl of the linear peptide. The crude production was cleaved from the resin together with all protecting group and identified and separated by MALDI-MS and RP-HPLC. The peptide yield was 18%, after purification the purity was more than 97%. It was identified on MALDI-MS and Ellman reagent detection. This method is effective, simple, rapid and obtained good yield, and it's fit for the large-scale production.
Amino Acids ; chemistry ; Combinatorial Chemistry Techniques ; methods ; Disulfides ; chemistry ; Fluorenes ; chemistry ; Molecular Structure ; Peptides, Cyclic ; chemical synthesis ; chemistry ; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization

This study is (1) to improve the stabilization of human scFv to rabies virus; (2) to prepare active human dsFv fragment; and (3) to evaluate the biological activities of dsFv. The dsFv V(H) and VL were separately expressed in PET22b(+)/BL21 (DE3), solublized and combined in appropriate molar ratio in refolding solution. The resultant dsFv fragments were evaluated for its protection against rabies virus, its affinity and stability, in reference to the cognate scFv. The dsFv was found to bind specifically to Vero vaccine of rabies virus. Compared to the scFv, the dsFv was more stable, had higher affinity, and was able to inhibit the infection of Rabies virus to Vero cell. This established a solid basis for the clinical application of dsFv to rabies virus.
Antibodies, Viral ; immunology ; Disulfides ; chemistry ; Humans ; Immunoglobulin Fragments ; immunology ; metabolism ; Immunoglobulin Variable Region ; immunology ; metabolism ; Rabies virus ; immunology

OBJECTIVETo investigate the tissue distribution of the diallyl disulfide (DADS) and diallyl trisulfide (DATS) in solid lipid nanoparticles loaded garlic oil (GO-SLN) in rats.

METHODThe gas chromatography-electron capture detection (GC-ECD) method was established to determined the DADS and DATS simultaneously in the biological samples of rats after administration of 0.5 mL garlic oil injection or GO-SLN (containing about 10 mg garlic oil) via jugular vein cannula. The conditions for gas chromatographic separation were as follows. The oven temperature was set at 110 degrees C and maintained for 15 min. Temperatures at the injection port and detector were 180 degrees C and 300 degrees C, respectively. Ultra-pure nitrogen (purity > 99.999%, Shenyang Kerui Special Gases Co. Ltd., China) was used as a carrier gas and made-up gas at flow-rates of 1 mL x min(-1) and 60 mL x min(-1), respectively. All injections were carried out in the split injection mode with a split ratio of 1:10.

RESULTThe GC-ECD method was fit for determing the concentration of DADS and DATS in garlic oil. The distribution character of GO-SLN in rats had changed to some extent and the concentration of GO-SLN in tissues was higher than that of GO-Injection.

CONCLUSIONThe SLN can elevate the passive targeting of drugs and lengthen their action time in tissues.

Allyl Compounds ; analysis ; pharmacokinetics ; Animals ; Disulfides ; analysis ; pharmacokinetics ; Female ; Garlic ; chemistry ; Male ; Nanoparticles ; administration & dosage ; chemistry ; Plant Oils ; administration & dosage ; chemistry ; pharmacokinetics ; Rats ; Rats, Wistar ; Sulfides ; analysis ; pharmacokinetics

The molecular characterization and phylogenetic analysis of hemagglutinin (HA) genes of human influenza H3N2 viruses in Guangdong, China from 2007 to 2010 were studied in this study. By space-time sampling of strains, the HA genes of H3N2 strains from Guangdong were sequenced and searched from Internet, and then the variation and evolution of HA genes were conducted by Lasergene 7.1 and Mega 5.05 and evolutionary rates were analyzed by epidemiological data. The phylogenetic tree was established by alignment of 17 Guangdong strains and 26 global reference strains. Ks rates and Ka rates of HA genes were 2.06 x 10(-3)-2.23 x 10(-3) Nt/Year and 1.05 x 10(-3)-1.21 x 10(3) Nt/Year during 2007-2010, while the velocity of HA1 evolution of Ka was 3. 13 times than that of HA2 evolution. Compared with HA of vaccine strain A/Perth/16/2009, the genetic homologies of Guangdong strains in 2009 reached to 98.8%-99.7% and of Guangdong strains in 2010 reached to 98.0%-98.4%. There were some amino acid substitutions in five epitope regions of HA1 during 2007-2010, especially in B region (N160K) and D region (K174R/N); the K189E/N/Q and T228A in RBS (receptor-binding site) occurred in 2010 as two glycoproteins sites substituted impacted on the HA1 antigenicity. The antigenicity of epidemic H3N2 strains in 2010 was to some degree different that of the vaccine strain A/ Perth/16/2009. According to that there were variations of B and D epitopes and two sites of RBS and two glycoprotein in Guangdong H3N2 HA1 genes, WHO/ CDC should recommend new representative strains during 2011-2012 influenza seasons if H3N2 HA genes further evolve in the near future.
Amino Acid Substitution ; China ; Disulfides ; chemistry ; Epitopes ; genetics ; Evolution, Molecular ; Hemagglutinin Glycoproteins, Influenza Virus ; chemistry ; genetics ; immunology ; Humans ; Influenza A Virus, H3N2 Subtype ; genetics ; Mutation ; Phylogeny

The recently identified interleukin-17 (IL-17) cytokines family, which comprises six members in mammals (IL-17A-F), plays essential roles in the host immunity against infectious diseases and chronic inflammatory diseases. The three-dimensional structures containing IL-17A or IL-17F have become available and revealed the unique structural features of IL-17s as well as their receptors. Molecular modeling in this review shows that IL-17s may adopt a "cysteine knot" fold commonly seen in nerve growth factor (NGF) and other neurotrophins. Further modeling analysis unmasks a signature interaction feature of the IL-17F/IL-17RA complex, where a small loop of IL-17RA slots into the deep groove of the interface of IL-17F homodimer. This is quite different from the interaction between the best known four-helix cytokines and their cognate receptors. On the other hand, structure of IL-17A and its monoclonal antibody (CAT-2200) shows that, albeit that the antigenic epitope of IL-17A resides outside of the IL-17A homodimer interface, its physical proximity to the receptor binding groove may explain that antibody blockage would be achieved by interfering with the ligand-receptor interaction. This review is to summarize the advance in understanding the structure and function of IL-17 family cytokines, focusing mainly on IL-17A, IL-17F and IL-17E, in the hope of gaining better knowledge of immunotherapeutic strategies against various inflammatory diseases.
Amino Acid Sequence ; Animals ; Conserved Sequence ; Cysteine ; Disulfides ; chemistry ; Humans ; Interleukin-17 ; chemistry ; metabolism ; Molecular Sequence Data ; Protein Structure, Secondary ; Protein Structure, Tertiary ; Receptors, Interleukin ; metabolism

To establish a refolding process for the protein fused with 12-peptide of hirudin and reteplase (HV12p-rPA), we developed an anion-exchange chromatography assisted method to form correct disulfide bonds. After evaluating various parameters by orthogonal experiments with Q Sepharose XL as refolding medium, we found that urea gradient, sample loading size and L-Arg concentration were three major factors to affect the refolding outcomes, and urea gradient was critical to the recovery yield. Meanwhile, enzymatic activity of the refolded protein was decreased by the increase of sample loading size, and the optimal concentration of L-Arg in the eluting buffer was 1 mol/L. Thus, a dual-gradient of urea and pH on the anion-exchange chromatography resulted in remarkable increase of specific fibrinolytic and anti-coagulative activities of the refolded protein. Compared with the dilution method for refolding HV12p-rPA, the present approach was more effective and advantageous.
Chromatography, Ion Exchange ; methods ; Disulfides ; chemistry ; Fibrinolytic Agents ; analysis ; chemistry ; Hirudins ; analysis ; chemistry ; Protein Refolding ; Recombinant Fusion Proteins ; analysis ; chemistry ; Recombinant Proteins ; analysis ; chemistry ; Tissue Plasminogen Activator ; analysis ; chemistry

Histone deacetylase (HDAC) has been highlighted as one of key players in tumorigenesis and angiogenesis. Recently, several derivatives of psammaplin (Psams) from a marine sponge have been known to inhibit the HDAC activity, but the molecular mechanism for the inhibition has not fully understood. Here, we explored the mode of action of Psams for the inhibition of HDAC activity in the molecular and cellular level. Among the derivatives, psammaplin A (Psam A) showed the potent inhibitory activity in enzyme assay and anti-proliferation assay with IC50 value of 0.003 and 1 microM, respectively. Psam A selectively induced hyperacetylation of histones in the cells, resulting in the upregulation of gelsolin, a well-known HDAC target gene, in a transcriptional level. In addition, reduced Psam A showed a stronger inhibitory activity than that of non-reduced one. Notably, glutathione-depleted cells were not sensitive to Psam A, implying that cellular reduction of the compound is responsible for the HDAC inhibition of Psam A after uptake into the cells. Together, these data demonstrate that Psam A could exhibit its activity under the reduced condition in the cells and be a new natural prodrug targeting HDAC.
Tyrosine/*analogs & derivatives/chemistry/pharmacology ; Prodrugs/chemistry/*pharmacology ; Oxidation-Reduction ; Molecular Structure ; Humans ; Histones/metabolism ; Histone Deacetylases/*antagonists & inhibitors/*classification/genetics/metabolism ; Hela Cells ; Enzyme Inhibitors/chemistry/*pharmacology ; Disulfides/chemistry/*pharmacology ; Cell Proliferation ; Biological Products/chemistry/*pharmacology ; Acetylation

OBJECTIVETo investigate the molecular mechanisms of Z-ajoene mitosis blocking and telomerase inhibitory effects on HL-60 cells.

METHODSProliferation inhibition of HL-60 cell line was evaluated by MTT assay. Z-ajoene-induced mitotic blocking effect was investigated by flow cytometry. Immunoblotting analysis was used to determine cell cycle regulatory proteins. The telomerase activity of HL-60 cells was detected by TRAP-silver stain assay. Telomerase hTRT and TP1 mRNA level were determined by RT-PCR.

RESULTSZ-ajoene displayed great proliferation inhibiting effect on HL-60 cells. Progressive increase in the percentage of mitotic block at G(2)/M phase was observed from 4 h to 12 h after treatment with 10 micromol/L Z-ajoene, with a peak at 10 h, which was 1.95 times higher than that in control. Z-ajoene also caused an increase in cyclin B1 accumulation and a decrease of p34(cdc2) expression. But Z-ajoene did not change the level of cyclin A. After treating with 10 micromol/L Z-ajoene for 24 h, the telomerase activity of HL-60 cells was also decreased in a dose-independent manner. Furthermore, telomerase hTRT and TP1 mRNA levels decreased after 10 micromol/L Z-ajoene treatment for 24 h.

CONCLUSIONThe results suggest that Z-ajoene has potent anti-cancer activity, and that its inhibitory effect on telomerase activity and on cell growth might be the result of G(2)/M phase blocking.

Antineoplastic Agents, Phytogenic ; pharmacology ; Cell Cycle ; drug effects ; Disulfides ; pharmacology ; Garlic ; chemistry ; HL-60 Cells ; Humans ; Mitosis ; drug effects ; Telomerase ; metabolism