Faculty Opinions recommendation of Disulfide-bond formation in the transthyretin mutant Y114C prevents amyloid fibril formation in vivo and in vitro.

2002 ◽  
Author(s):  
Vivian Cody
Keyword(s):  
Disulfide Bond ◽  
Amyloid Fibril ◽  
Bond Formation ◽  
Fibril Formation ◽  
Disulfide Bond Formation ◽  
Amyloid Fibril Formation

scholarly journals On the Functional Interchangeability, Oxidant versus Reductant, of Members of the Thioredoxin Superfamily

2000 ◽  
Vol 182 (3) ◽  
pp. 723-727 ◽  
Author(s):  
Laurent Debarbieux ◽  
Jon Beckwith
Keyword(s):  
Disulfide Bond ◽  
Disulfide Bonds ◽  
Signal Sequence ◽  
Cell Envelope ◽  
Bond Formation ◽  
Disulfide Bond Formation ◽  
Thioredoxin 1 ◽  
High Level

ABSTRACT Escherichia coli thioredoxin 1 has been characterized in vivo and in vitro as one of the most efficient reductants of disulfide bonds. Nevertheless, under some conditions, thioredoxin 1 can also act in vivo as an oxidant, promoting formation of disulfide bonds in the cytoplasm (E. J. Stewart, F. Åslund, and J. Beckwith, EMBO J. 17:5543–5550, 1998). We recently showed that when a signal sequence is attached to thioredoxin 1 it is exported to the periplasm, where it can also act as an oxidant, replacing the normal periplasmic catalyst of disulfide bond formation, DsbA, in oxidizing cell envelope proteins (L. Debarbieux and J. Beckwith, Proc. Natl. Acad. Sci. USA 95:10751–10756, 1998). Here we report pulse-chase studies of the efficiency of disulfide bond formation in strains exporting thioredoxin 1 and more-oxidizing variants of it. While the exported thioredoxin 1 itself substantially speeds up the kinetics of disulfide bond formation, a version of this protein containing the DsbA active site exhibits kinetics that are indistinguishable from those of the DsbA protein itself. Further, we confirm the findings of Jonda et al. (S. Jonda, M. Huber-Wunderlich, R. Glockshuber, and E. Mössner, EMBO J. 18:3271–3281, 1999), who found that DsbB is responsible for the oxidation of exported thioredoxin 1, and we report the detection of a disulfide-bonded DsbB-thioredoxin 1 complex. Finally, we have found that under conditions of high-level expression of exported thioredoxin 1, the protein can act as both an oxidant and a reductant.

Covalent assembly of mouse immunoglobulin G subclasses in vitro: application of a theoretical model for interchain disulfide bond formation

1976 ◽  
Vol 54 (8) ◽  
pp. 675-687 ◽  
Author(s):  
M. E. Percy ◽  
R. Baumal ◽  
K. J. Dorrington ◽  
J. R. Percy
Keyword(s):  
Theoretical Model ◽  
Disulfide Bond ◽  
Immunoglobulin G ◽  
Bond Formation ◽  
Second Phase ◽  
Disulfide Bond Formation ◽  
Interchain Disulfide Bond ◽  
Mouse Immunoglobulin

The pathways and kinetics of interchain disulfide bond formation have been determined in vitro for purified myeloma proteins representing the three major subclasses of mouse immunoglobulin G (IgG)using the reoxidation system described previously (Petersen, J. G. L. &Dorrington, K. J. (1974) J. Biol. Chem. 249, 5633–5641). Mixtures of oxidized and reduced glutathione were added to act as a disulfide interchange catalyst. The pathways of covalent assembly observed in vitro were qualitatively and quantitatively similar to those followed by the various subclasses in vivo. HH and HHL were the principle covalent intermediates seen with IgG1 (MOPC 31C) and IgG2a (MOPC 173 and clone 19). With IgG2b (MPC 11C), HL, HH and HHL were all prominant intermediates.The time courses of reoxidation were simulated using a theoretical model based on second-order reaction kinetics (Percy, J. R., Percy, M. E. &Dorrington, K. J. (1974) J. Biol. Chem. 250, 2398–2400). Two distinct phases were apparent in the reoxidation sequence. The first, which lasted for the initial 5–15 min, did not conform to the theoretical model. The second phase could be accounted for by the model and represented the remainder of the covalent assembly process. The physico-chemical basis for this biphasic phenomenon was explored. Sedimentation velocity studies showed that noncovalent association was incomplete at the beginning of the reoxidation step for all proteins except IgG2b (MOPC 11C). No dissociation was apparent in the reduced and alkylated proteins at pH 5 in the absence of prior exposure to acid conditions. Thus, exposure to acid appears to affect the affinity between the subunits in the native proteins. Transfer of the proteins from pH 5 to pH 8.2 (the pH at which reoxidation proceeds) is accompanied by the generation of an absorption difference spectrum over an 8–10-min period. These data suggest that a pH-dependent conformational relaxation process may influence the early stages of reoxidation.

Effect of pH and inhibitors on beta-amyloid fibril assembly

1996 ◽  
Vol 54 ◽  
pp. 752-753
Author(s):  
Beverly E. Maleeff ◽  
Timothy K. Hart ◽  
Stephen J. Wood ◽  
Ronald Wetzel
Keyword(s):  
Amyloid Fibril ◽  
Peptide Fragment ◽  
Hydrophobic Peptides ◽  
Amyloid Fibril Formation ◽  
Effects Of Ph ◽  
Severity Of The Disease ◽  
Kinetics Of ◽  
The Brain

Alzheimer's disease is characterized post-mortem in part by abnormal extracellular neuritic plaques found in brain tissue. There appears to be a correlation between the severity of Alzheimer's dementia in vivo and the number of plaques found in particular areas of the brain. These plaques are known to be the deposition sites of fibrils of the protein β-amyloid. It is thought that if the assembly of these plaques could be inhibited, the severity of the disease would be decreased. The peptide fragment Aβ, a precursor of the p-amyloid protein, has a 40 amino acid sequence, and has been shown to be toxic to neuronal cells in culture after an aging process of several days. This toxicity corresponds to the kinetics of in vitro amyloid fibril formation. In this study, we report the biochemical and ultrastructural effects of pH and the inhibitory agent hexadecyl-N-methylpiperidinium (HMP) bromide, one of a class of ionic micellar detergents known to be capable of solubilizing hydrophobic peptides, on the in vitro assembly of the peptide fragment Aβ.

scholarly journals Disulfide Bond Formation at the C Termini of Vaccinia Virus A26 and A27 Proteins Does Not Require Viral Redox Enzymes and Suppresses Glycosaminoglycan-Mediated Cell Fusion

2009 ◽  
Vol 83 (13) ◽  
pp. 6464-6476 ◽  
Author(s):  
Yao-Cheng Ching ◽  
Che-Sheng Chung ◽  
Cheng-Yen Huang ◽  
Yu Hsia ◽  
Yin-Liang Tang ◽  
...  
Keyword(s):  
Vaccinia Virus ◽  
Cell Fusion ◽  
Disulfide Bond ◽  
Protein Complex ◽  
Disulfide Bonds ◽  
Bond Formation ◽  
In Vitro Mutagenesis ◽  
Disulfide Bond Formation ◽  
Infected Cells

ABSTRACT Vaccinia virus A26 protein is an envelope protein of the intracellular mature virus (IMV) of vaccinia virus. A mutant A26 protein with a truncation of the 74 C-terminal amino acids was expressed in infected cells but failed to be incorporated into IMV (W. L. Chiu, C. L. Lin, M. H. Yang, D. L. Tzou, and W. Chang, J. Virol 81:2149-2157, 2007). Here, we demonstrate that A27 protein formed a protein complex with the full-length form but not with the truncated form of A26 protein in infected cells as well as in IMV. The formation of the A26-A27 protein complex occurred prior to virion assembly and did not require another A27-binding protein, A17 protein, in the infected cells. A26 protein contains six cysteine residues, and in vitro mutagenesis showed that Cys441 and Cys442 mediated intermolecular disulfide bonds with Cys71 and Cys72 of viral A27 protein, whereas Cys43 and Cys342 mediated intramolecular disulfide bonds. A26 and A27 proteins formed disulfide-linked complexes in transfected 293T cells, showing that the intermolecular disulfide bond formation did not depend on viral redox pathways. Finally, using cell fusion from within and fusion from without, we demonstrate that cell surface glycosaminoglycan is important for virus-cell fusion and that A26 protein, by forming complexes with A27 protein, partially suppresses fusion.

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