disulfide bond

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bond

 [bond]
the linkage between atoms or radicals of a chemical compound, or the symbol representing this linkage and indicating the number and attachment of the valencies of an atom in constitutional formulas, represented by a pair of dots or a line between atoms, e.g., H—O—H, H—C≡C—H or H:O:H, H:C:::C:H.
coordinate covalent bond a covalent bond in which one of the bonded atoms furnishes both of the shared electrons.
covalent bond a chemical bond between two atoms or radicals formed by the sharing of a pair (single bond), two pairs (double bond), or three pairs of electrons (triple bond).
disulfide bond a strong covalent bond, —S—S—, important in linking polypeptide chains in proteins, the linkage arising as a result of the oxidation of the sulfhydryl (SH) groups of two molecules of cysteine.
high-energy phosphate bond an energy-rich phosphate linkage present in adenosine triphosphate (ATP), phosphocreatine, and certain other biological molecules. On hydrolysis at pH 7 it yields about 8000 calories per mole, in contrast to the 3000 calories yielded by phosphate esters. The bond stores energy that is used to drive biochemical processes, such as the synthesis of macromolecules, contraction of muscles, and the production of the electrical potentials for nerve conduction.
high-energy sulfur bond an energy-rich sulfur linkage, the most important of which occurs in the acetyl-CoA molecule, the main source of energy in fatty acid biosynthesis.
hydrogen bond a weak, primarily electrostatic, bond between a hydrogen atom bound to a highly electronegative element (such as oxygen or nitrogen) in a given molecule, or part of a molecule, and a second highly electronegative atom in another molecule or in a different part of the same molecule.
ionic bond a chemical bond in which electrons are transferred from one atom to another so that one bears a positive and the other a negative charge, the attraction between these opposite charges forming the bond.
peptide bond the —CO—NH— linkage formed between the carboxyl group of one amino acid and the amino group of another; it is an amide linkage joining amino acids to form peptides.

di·sul·fide bond

a single bond between two sulfurs; specifically, the -S-S- link binding two peptide chains (or different parts of one peptide chain); also occurs as part of the molecule of the amino acid, cystine, and is important as a structural determinant in many peptide and protein molecules, for example, keratin, insulin, and oxytocin. A symmetric disulfide is R-S-S-R; R'-S-S-R is a mixed or asymmetric disulfide.

di·sul·fide bond

(dī-sŭl'fīd bond)
A single bond between two sulfurs; specifically, the -S-S- link binding two peptide chains (or different parts of one peptide chain).
Synonym(s): disulphide bond.
References in periodicals archive ?
When in the same environment with ROS, - SH groups are oxidised and form reversible disulphide bonds. But formed disulphide bonds may again be reduced to thiol groups by the cellular-reducing effects of some anti-oxidants, and thiol-disulphide homeostasis is kept by this mechanism.
Histochemical examination of hair has shown that in the trichilemmal sac encircling hair the germinal cells rich in free thiol groups are abundant, and disulphide bonds limit themselves (24).
The number of disulphide bonds is given by half the value of the difference between total and native thiols.
For that purpose, the content of free sulphydryl groups (SH), disulphide bonds (SS), and free amino groups (N[H.sub.2]) as indicators of gluten quality was determined.
(48) In addition, the activation of chicken TRPV1 was proposed to be a consequence of dimerization through the formation of a disulphide bond. (49) Because all of the above models of oxidation-induced TRPV1 activation are based on Cys mutagenesis, it is still possible that the suppression of activation is due to non-specific structural disruption of the protein.
In short, disulphide bonds were first reduced to form-free functional thiol groups with sodium borohydride.
Nevertheless, this study showed that the maximum CLD resulting from disulphide bonds seems to be too low for a significant improvement of barrier properties.
The product (Lipoic Acid Choline Ester, 1.5%) is a first-in-class new chemical entity that targets a biochemical cause of presbyopia, believed to be associated with an increase in the formation of disulphide bonds between the crystalline proteins within lens fibre cells.
By supporting intact protein analysis, peptide mapping, N- and C-terminal analysis, glycopeptides and released glycans, and prediction of disulphide bonds, Genedata Expressionist for MS helps users with the analysis of the following MS-based applications:
Accurate formation of disulphide bonds; which has been overwhelmingly considered as a major post-translational modification aspect, should be strongly spotted (9).
Polypeptides fold further as adjacent cysteine amino acids cross-link to form disulphide bonds; these determine the tensile strength, and whether hair is naturally straight or curly.
The normal kind of bonds - disulphide bonds - can be broken by changes in heat and acidity, causing proteins to lose their 3D structure.