Latest revision as of 14:11, 21 February 2025

Disulfide[edit]

3D structure of cystine, a common disulfide.

A disulfide is a functional group with the structure R-S-S-R', where R and R' are organic groups. The linkage is also called a disulfide bridge or disulfide bond. Disulfides are important in the structure and function of many proteins and enzymes.

Structure and Properties[edit]

Disulfide bonds are formed by the oxidation of two thiol groups, resulting in the linkage of two sulfur atoms. This bond is relatively stable and can significantly influence the tertiary and quaternary structure of proteins.

The disulfide bond is a covalent bond, and its formation is a reversible process. The bond can be broken by reduction, converting the disulfide back to two thiol groups.

Biological Significance[edit]

Disulfide bonds play a crucial role in the folding and stability of proteins. They are often found in extracellular proteins, where they help maintain the protein's structure in the oxidizing environment outside the cell.

Cystine[edit]

Cystine is a dimeric amino acid formed by the oxidation of two cysteine molecules, linked by a disulfide bond. It is a key structural component in many proteins, including keratin and insulin.

Lipoic Acid[edit]

Lipoic acid is a cofactor for enzymatic reactions and contains a disulfide bond that is essential for its biological activity. It plays a role in the pyruvate dehydrogenase complex and other dehydrogenase complexes.

Chemical Reactions[edit]

Disulfides can undergo various chemical reactions, including reduction to thiols and exchange reactions with other thiols.

Thiol-Disulfide Exchange[edit]

Illustration of thiol-disulfide exchange reaction.

Thiol-disulfide exchange is a common reaction where a thiol group attacks a disulfide bond, resulting in the formation of a new disulfide and a new thiol. This reaction is important in redox biology and protein folding.

Industrial and Environmental Aspects[edit]

Disulfides are also found in various industrial and environmental contexts. For example, carbon disulfide is used as a solvent and in the production of rayon and cellophane.

Mineralogy[edit]

Disulfide bonds are present in some minerals, such as molybdenite, which contains molybdenum disulfide (MoS₂).

Related Pages[edit]

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-{{Short description|Overview of disulfide bonds in biochemistry}}
+= Disulfide =
-==Disulfide Bonds==
+[[File:Cystine-from-xtal-Mercury-3D-balls-thin.png|thumb|right|3D structure of cystine, a common disulfide.]]
-[[File:Disulfide-bond.png|thumb|right|200px|Diagram of a disulfide bond between two cysteine residues.]]
-A '''disulfide bond''' (also known as an '''S-S bond''' or '''disulfide bridge''') is a covalent bond derived from two thiol groups. In biochemistry, disulfide bonds are crucial for the stabilization of the tertiary and quaternary structures of proteins.
-==Formation and Structure==
+A '''disulfide''' is a functional group with the structure R-S-S-R', where R and R' are organic groups. The linkage is also called a '''disulfide bridge''' or '''disulfide bond'''. Disulfides are important in the structure and function of many proteins and enzymes.
-Disulfide bonds are formed by the oxidation of two [[cysteine]] residues, resulting in the linkage of their sulfur atoms. This reaction can be represented as:
-: 2 R-SH _ R-S-S-R + 2 H_ + 2 e_
+== Structure and Properties ==
-where R-SH represents a thiol group. The resulting bond is a covalent linkage between the sulfur atoms of two cysteine residues, forming a cystine.
+Disulfide bonds are formed by the oxidation of two [[thiol]] groups, resulting in the linkage of two sulfur atoms. This bond is relatively stable and can significantly influence the tertiary and quaternary structure of proteins.
-==Role in Protein Structure==
+[[File:Disulfide_Bridges_(SCHEMATIC)_V.1.svg|thumb|left|Schematic representation of disulfide bridges in proteins.]]
-[[File:Protein-disulfide-bond.png|thumb|left|200px|Disulfide bonds help stabilize protein structures.]]
-Disulfide bonds play a critical role in the folding and stability of proteins. They are often found in extracellular proteins and secreted proteins, where they help maintain structural integrity under varying environmental conditions. The presence of disulfide bonds can significantly increase the thermal and chemical stability of proteins.
-==Biological Significance==
+The disulfide bond is a covalent bond, and its formation is a reversible process. The bond can be broken by reduction, converting the disulfide back to two thiol groups.
-Disulfide bonds are essential in the formation of the active conformation of many proteins. For example, they are crucial in the structure of antibodies, insulin, and many enzymes. In antibodies, disulfide bonds link the heavy and light chains, stabilizing the overall structure.
-==Disulfide Bond Formation==
+== Biological Significance ==
-The formation of disulfide bonds in proteins occurs in the [[endoplasmic reticulum]] of eukaryotic cells. This process is facilitated by protein disulfide isomerase (PDI), which catalyzes the formation and rearrangement of disulfide bonds.
-==Reduction and Rearrangement==
+Disulfide bonds play a crucial role in the folding and stability of proteins. They are often found in extracellular proteins, where they help maintain the protein's structure in the oxidizing environment outside the cell.
-Disulfide bonds can be reduced back to thiol groups by reducing agents such as [[dithiothreitol]] (DTT) or [[_-mercaptoethanol]]. This reduction is often used in laboratory settings to denature proteins for analysis by [[SDS-PAGE]].
-==Applications in Biotechnology==
+=== Cystine ===
-Disulfide bonds are exploited in biotechnology for the design of stable protein therapeutics and in the engineering of proteins with enhanced stability. They are also used in the development of biosensors and other diagnostic tools.
-==Related Pages==
+[[File:Cystine-skeletal.png|thumb|right|Skeletal structure of cystine.]]
+Cystine is a dimeric amino acid formed by the oxidation of two [[cysteine]] molecules, linked by a disulfide bond. It is a key structural component in many proteins, including [[keratin]] and [[insulin]].
+=== Lipoic Acid ===
+[[File:Lipoic-acid-from-xtal-3D-bs-17.png|thumb|left|3D structure of lipoic acid.]]
+Lipoic acid is a cofactor for enzymatic reactions and contains a disulfide bond that is essential for its biological activity. It plays a role in the [[pyruvate dehydrogenase complex]] and other [[dehydrogenase]] complexes.
+== Chemical Reactions ==
+Disulfides can undergo various chemical reactions, including reduction to thiols and exchange reactions with other thiols.
+=== Thiol-Disulfide Exchange ===
+[[File:Thiol_disulfide_exchange.png|thumb|right|Illustration of thiol-disulfide exchange reaction.]]
+Thiol-disulfide exchange is a common reaction where a thiol group attacks a disulfide bond, resulting in the formation of a new disulfide and a new thiol. This reaction is important in [[redox]] biology and protein folding.
+== Industrial and Environmental Aspects ==
+Disulfides are also found in various industrial and environmental contexts. For example, [[carbon disulfide]] is used as a solvent and in the production of [[rayon]] and [[cellophane]].
+[[File:Carbon-disulfide-3D-balls.png|thumb|left|3D structure of carbon disulfide.]]
+== Mineralogy ==
+Disulfide bonds are present in some minerals, such as [[molybdenite]], which contains molybdenum disulfide (MoS₂).
+[[File:Molybdenite-3D-balls.png|thumb|right|3D structure of molybdenite.]]
+== Related Pages ==
+* [[Thiol]]
 * [[Cysteine]]
-* [[Protein structure]]
+* [[Protein folding]]
-* [[Endoplasmic reticulum]]
+* [[Redox]]
-* [[Protein disulfide isomerase]]
-[[Category:Biochemistry]]
+[[Category:Chemical bonding]]
-[[Category:Protein structure]]
+[[Category:Proteins]]
+[[Category:Organosulfur compounds]]

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