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Topic: Disulphide bond

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  Disulphide Bonds
All of the stabilizing effect of a disulphide bond is proposed to come from the decrease in conformational entropy of the unfolded state, as described in Conformational Entropy of Unfolding, above.
Experiments in which naturally occurring disulphides are either mutated to alanine, or chemically reduced and blocked, lead to decreased stability ranging from 2 - 8 kcal/mol (Betz, 1993 and references therein).
It is worth noting that small proteins are often naturally rich in disulphide bonds (examples are shown in Jane Richardson's Protein Tourist kinamage); perhaps, when the geometry is optimal, they compensate for the small number of non-covalent interactions.
www.cryst.bbk.ac.uk /PPS2/projects/day/TDayDiss/DisulphideBonds.html   (459 words)

  Disulfide bond - Wikipedia, the free encyclopedia
Disulfide bonds play an important protective role for bacteria as a reversible switch that turns a protein on or off when bacterial cells are exposed to oxidation reactions.
In eukaryotic cells, disulfide bonds are generally formed in the lumen of the RER (rough endoplasmic reticulum) but not in the cytosol.
It is breaking and remaking of the disulfide bonds which is the basis for the permanent wave.
en.wikipedia.org /wiki/Disulphide_bond   (524 words)

 [No title]
1426288"Activity, disulphide mapping and structural modelling of the fifth domain of human beta 2-glycoprotein I." 1426288In an attempt to define the 3D structure of this domain, the disulphide linkage pattern was determined and shown to be Cys 1-4, Cys 2-5 and Cys 3-6 in contradiction to an earlier report.
2223768All cysteines are engaged as disulfide bonds: Cys(13)-Cys(59), Cys(48)-Cys(66), and Cys(79)-Cys(146).
The disulphide bridges of bovine chymotrypsinogen A." 6006643"The amino acid sequences around the disulfide bonds of soybean trypsin inhibitor." 6162107"Assignment of the disulphide bonds of leukocyte interferon." 6162107The results indicate that Cys 1 is bonded to Cys 98, and Cys 29 is bonded to Cys 138.
biomint.isb-sib.ch /SIB-Corpora/disulfid_bond_sent.txt   (9696 words)

 Prediction of cystine connectivity using SVM (support vector machines) - Bioinformation Journal for Beyond ...   (Site not responding. Last check: 2007-09-08)
Prediction of such disulphide bridges from sequence is challenging given that the possible combination of cysteine pairs as the number of cysteines increases in a protein.
Nonetheless, this task is non-trivial and predictions of disulphide bonds are generally preformed with and without prior knowledge on cysteine bonding states in a sequence of interest.
Prediction of disulphide bonding patterns with prior knowledge on the bonding state (6 different possible combinations) is relatively simpler to that without any prior knowledge on the bonding state of the cysteines (10 different possible combinations) in human alkaline phosphatase.
www.bioinformation.net /1/19-1-2005.htm   (1949 words)

Disulphide bonds increase the conformational stability mainly by constraining the unfolded conformations of the protein and thereby decreasing their conformational entropy (Pace, 1990).
Disulphide bond formation was found to be important in the present study.
As the disulphide bond in proteins are reduced, the protein unfolds or denatures.
www.friedli.com /herbs/phytochem/proteins.html   (11287 words)

 Results of the search
The disulphide bonds of the heavy chain of rabbit immunoglobulin G. I J O'Donnell...
Disulphide bonds assignment in the inter-alpha-inhibitor heavy chains--structural and functional implications.
Disulphide arrangement in bovine caseins: localization of intrachain disulphide bridges in monomers of kappa- and alpha s2-casein from bovine milk.
invention.swmed.edu /trite/abstracts/user-1016147978/results.shtml   (4206 words)

 disulphide bond
...the novel Raman spectroscopy based diagnostic test which is able to detect osteoporosis in its early stages by measuring the disulphide bond content of the...
This is a crucial bonding substance that gives both bones and fingernails their strength.
The researchers are now seeking funding to carry on their research so they can evaluate what level of disulphide bond indicates that someone is at risk of...
www.mongabay.com /igapo/biotech/disulphide_bond.html   (117 words)

 University of Oulu |
Protein folding in this context is often associated with the formation of native disulphide bonds, and this is facilitated by the enzyme protein disulphide isomerase (PDI).
In addition to its role in native disulphide bond formation, PDI is a subunit of two multisubunit complexes, one of which, prolyl-4-hydroxylase, is involved in collagen biogenesis.
Erp60 is involved in the formation of disulphide bonds in glycosylated proteins via its interaction with calnexin and calreticulin.
www.biochem.oulu.fi /tutkimus/ruddock?D=D   (2091 words)

 Department of Biology   (Site not responding. Last check: 2007-09-08)
Previously we have characterised the folding and disulphide bond formation of model substrate proteins in mammalian cells and demonstrated that the formation of disulphide bonds requires the ER oxidase Ero1, which catalyses the oxidation of protein disulphide isomerase (PDI).
For correct (native) disulphide bonds to form there needs to be not only an oxidative pathway to introduce the disulphides, but also a reductive or isomerisation pathway to remove incorrect (non-native) disulphides.
Using this approach we showed that disulphide bond isomerisation or reduction requires the presence of reduced glutathione within the ER lumen and that whilst cells depleted of glutathione form disulphide bonds more rapidly, these disulphide bonds are non-native.
www.york.ac.uk /depts/biol/cfm/seminardetails.cfm?ID=88   (300 words)

 ESRF Highlights 2000: Life Sciences
Disulphide bonds fragment when the absorbed dose increases, and acidic residues become decarboxylated.
The clear order that is observed in the susceptibility to reduction of different disulphide bonds within a sample could be a simple measure of the environment of the disulphide bond.
It has been observed that during bond breakage one of the sulphur atoms remains relatively fixed in position, whereas the other is labile and this could be of direct relevance to understanding the dynamics of enzymes that require labile disulphide bonds for activity, such as thioredoxin and DsbA.
www.esrf.fr /info/science/highlights/2000/life-sci/LS7.html   (557 words)

 Efficient catalysis of disulphide bond rearrangements by protein disulphide isomerase
Here we report that PDI increases by a factor of 3,000–6,000 the rates of folding of kinetically trapped BPTI folding intermediates, in which native structure impedes disulphide bond formation.
By contrast, PDI has only small effects on the rate of disulphide bond formation in intermediates that are oxidized readily in the absence of PDI.
These results suggest that an important function of PDI is to catalyse disulphide bond formation and rearrangements within kinetically trapped, structured folding intermediates.
www.nature.com /nature/journal/v365/n6442/abs/365185a0.html   (424 words)

 [No title]   (Site not responding. Last check: 2007-09-08)
If there are several disulphide bond constraints, no suitable models of the backbone may be obtained even after prolonged searches by examining a huge number of conformations.
The N-terminal two disulphides are first generated using 'ran' ('ss' as the input file) and the third disulphide is modelled using 'randep' ('ssdep' and 'pep' as the input files).
For example, 59 0.6811 means that conformation was compatibile to accommodate all the disulphide bond constraints, but had 59 inter-atomic pairs within 1.89 angstroms, the worst being 0.6811 angstroms apart.
xray.utmb.edu /ranmod.html   (3405 words)

 CVR | Research Groups | Disulfide Exchange Group
We have shown that disulphide switching can control the activity of three proteins (plasmin, von Willebrand factor and CD4) and have preliminary data that supports control of another three proteins (tissue factor, CD8 and the prion protein) by this means.
As we learn more about how disulphide switching controls protein function the hope is that this knowledge can be used to predict whether a protein is likely to be controlled by this means based on its primary, secondary or tertiary structure.
To this end, we have identified a type of disulfide-bond called a cross-strand bond that may be the first example of a generic disulphide switch.
www.cvr.net.au /research/disulfide.htm   (866 words)

 Cross-Strand Disulphides in Cell Entry Proteins: Poised to Act
Disulphides are generally viewed as structurally stabilizing elements in proteins.
Disulphide redox potentials measured in thiol-disulphide oxidoreductases range from -120mV to -270mV (Wunderlich and Glockshuber, 1993; Huber-Wunderlich and Glockshuber, 1998; Lin and Kim, 1989; Krause et al, 1991).
The disulphide linkage forms across the two strands roughly perpendicular to the strand direction and parallel to the hydrogen bonds between the two strands.
iscb.org /ismb2004/posters/m.woutersATvictorchang.unsw.edu.au_642.html   (775 words)

 Details of Prion 3D Structure
The approximate lengths of the helices are from residues 144 to 154, 179 to 193, and 200 to 217, and the lengths of the p-strands are from residues 128 to 131, and 161 to 164.
The disulphide bond 179-214 is highly shielded from solvent contact in the core of the protein.
The disulphide bond between Cys 179 and Cys 214 is shown in white.
www.mad-cow.org /3d_text.html   (2376 words)

 Punjab Kesari NewsDetails
He found that levels of disulphide bond - needed to bind one protein molecule to another - were lower in people with osteoporosis.
In nails, the disulphide bond is needed to bind keratin - which gives them strength.
The researchers are now seeking funding to carry on their research so they can evaluate what level of disulphide bond indicates that someone is at risk of osteoporosis, or that they already have the disease.
www.punjabkesari.com /frmNewsDetails.aspx?uid=7483   (527 words)

 [No title]   (Site not responding. Last check: 2007-09-08)
The bond formed by oxidation of the thiol groups of two cysteine residues.Often a stabilizing force in protein structure.
An hydrogen bond is key to the interaction between biological molecules.
Angle of rotation of the bond between the nitrogen and the carbonyl carbon in an peptide bond.
xml.coverpages.org /testvhg980828.xml   (3184 words)

 UNSW Medicine - Research - Research at Medicine   (Site not responding. Last check: 2007-09-08)
Disulphide bonds are covalent links between pairs of cysteine amino acids.
There is emerging evidence for a third type of disulphide bond which can control protein function by triggering a conformational change when it breaks and/or forms.
We have predicted that about one in fifteen of all structurally determined disulphides is a potential allosteric bond, implying a significant role for these bonds in controlling protein function.
notes.med.unsw.edu.au /resinterests.nsf/sw/9100604   (581 words)

 Purified hepatitis C virus envelope proteins for diagnostic and therapeutic use - Patent 6150134
The present invention thus provides a means for selectively cleaving the disulphide bonds under specific conditions and for separating the cleaved proteins from contaminating proteins which greatly interfere with diagnostic, prophylactic and therapeutic applications.
Said disulphide bond cleavage (or reducing) step of the present invention is preferably a partial disulphide bond cleavage (reducing) step (carried out under partial cleavage or reducing conditions).
The term `disulphide bridge exchanging agent` is to be interpretated as including disulphide bond reforming as well as disulphide bond blocking agents.
www.freepatentsonline.com /6150134.html   (17822 words)

 Molecular Movement of the Voltage Sensor in a K Channel -- Broomand et al. 122 (6): 741 -- The Journal of General ...
that a disulphide bond was induced by Cu/phenanthroline (Fig.
Formation of disulphide bonds between residues in S4 and residues in the pore domain.
is that the disulphide bonds alter the equilibrium between the
www.jgp.org /cgi/content/full/122/6/741   (4553 words)

 Virology Journal | Full text | Importance of disulphide bonds for vaccinia virus L1R protein function
In this report conditional-lethal expression of L1R and complementation with a library of cysteine-to-serine L1R mutants was used to investigate the importance of disulphide bond formation and the presence of the contributing cysteine residues to protein function.
A recombinant virus was constructed in which the expression of the L1R gene could be regulated by the presence or absence of TET using the components of the bacterial tetracycline operon [7].
Protein disulphide isomerase is then necessary to resolve this mispairing and the disulphide bond that is formed by Cys-57 and its unknown partner is not necessary for functional L1R.
www.virologyj.com /content/2/1/91   (2262 words)

The Cys186-Cys209 TF bond has the same unusual configuration as the disulphide-bond in the second domain of CD4, which we have shown controls CD4 function by switching between oxidized (disulphide) and reduced (dithiol) states (Matthias et al.
The Cys186-Cys209 TF disulphide is exposed to solvent in the crystal structure (Harlos et al.
By labeling cells with a biotin-linked maleimide, we have demonstrated that the cross-strand bond in cryptic, but not active, TF is reduced on the cell surface.
www.blackwellpublishing.com /isth2005/abstract.asp?id=45330   (303 words)

 Hair Strength - Hair Dimension - How hair gets its shape   (Site not responding. Last check: 2007-09-08)
Many disulphide bonds form down the length of the keratin chains, joining them together like the rungs of a ladder.
The disulphide bond is one of the strongest bonds known anywhere in nature.
Hydrogen bonds are broken apart whenever the hair is wetted, and form again as it dries.
www.pg.com /science/haircare/hair_twh_18.htm;jsessionid=K0YJW4VF1VZEVQFIAJ1SZOWAVABHMLHC   (603 words)

 Redox property and regulation of PpsR, a transcriptional repressor of photosystem gene expression in Rhodobacter ...
of the disulphide bond in PpsR, and the mobility of the oxidized
by the reduction of the intramolecular disulphide bond in PpsR.
Fassio, A. and Sitia, R. Formation, isomerisation and reduction of disulphide bonds during protein quality control in the endoplasmic reticulum.
mic.sgmjournals.org /cgi/content/full/150/3/697   (4423 words)

 Poster Abstracts- Second International Conference on Protein Stabilisation
The introduction of a disulphide bond into a sensitive loop region of the thermolysin-like neutral protease from Bacillus stearothermophilus by site-directed mutagenesis resulted in an extreme stabilisation of the enzyme towards thermal inactivation [1].
Since denaturation of both the wild-type and the mutant enzymes is accompanied by rapid autoproteolytic degradation, it has not been possible to differentiate between stabilisation towards unfolding and stabilisation towards autoproteolysis, hitherto.
First unfolding studies by fluorescence spectroscopy suggest that the disulphide bond effects a real conformational stabilisation of the protease molecule towards global unfolding.
www.ejbiotechnology.info /feedback/proceedings/04/poster/p42.html   (322 words)

 The three dimensional structure of the type I insulin-like growth factor receptor -- Ward et al. 54 (3): 125 -- ...   (Site not responding. Last check: 2007-09-08)
Cys1-Cys2 (loop 1), Cys3-Cys5, and Cys4-Cys6 (loop 2) disulphide
The disulphide bonds in the C-terminal domains of the human insulin receptor ectodomain.
Lu K, Guidotti G. Identification of the cysteine residues involved in the class I disulphide bonds of the human insulin receptor: properties of insulin receptor monomers.
mp.bmjjournals.com /cgi/content/full/54/3/125   (4629 words)

 Corante > Living Code > Mutants Make Clusters   (Site not responding. Last check: 2007-09-08)
Bacteria that already contained successful genetic changes were selected out from the millions of bacteria that could not survive due to the inability to make disulphide bonds.
If there was no way that thioredoxin COULD ever be made to create disulphide bonds, this experiment would have failed.
That mutating thioredoxin could create such a cluster, and that such a cluster could actually correct the disulphide bond defect in the mutant bacteria, is unprecedented and extremely interesting.
www.corante.com /livingcode/archives/003100.html   (667 words)

 Disruption of one intra-chain disulphide bond in the carboxyl-terminal propeptide of the pro{alpha}1(I) chain of type I ...   (Site not responding. Last check: 2007-09-08)
Disruption of one intra-chain disulphide bond in the carboxyl-terminal propeptide of the pro{alpha}1(I) chain of type I procollagen permits slow assembly and secretion of overmodified, but stable procollagen trimers and results in mild osteogenesis imperfecta -- Pace et al.
bond formation, and were slow to assemble into dimers and trimers.
Common among the mutations that alter intra-chain disulphide bonding is that they result in the slowed formation of overmodified
jmg.bmjjournals.com /cgi/content/full/38/7/443   (3914 words)

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