disulfide bond

Examples of disulfide bond in the following topics:

• The Sulfur Cycle

  • As a part of the amino acid cysteine, it is involved in the formation of disulfide bonds within proteins, which help to determine their 3-D folding patterns and, hence, their functions.

• Protein Structure

  • Cysteine side chains form disulfide linkages in the presence of oxygen, the only covalent bond forming during protein folding.
  • Enzymes often play key roles in bonding subunits to form the final, functioning protein.
  • For example, insulin is a ball-shaped, globular protein that contains both hydrogen bonds and disulfide bonds that hold its two polypeptide chains together.
  • Silk is a fibrous protein that results from hydrogen bonding between different β-pleated chains.
  • The tertiary structure of proteins is determined by hydrophobic interactions, ionic bonding, hydrogen bonding, and disulfide linkages.

• Hydrogen Bonding and Van der Waals Forces

  • Hydrogen bonds and van der Waals interactions are two types of weak bonds that are necessary to the basic building blocks of life.
  • However, not all bonds are ionic or covalent bonds.
  • Weaker bonds can also form between molecules.
  • Two weak bonds that occur frequently are hydrogen bonds and van der Waals interactions.
  • This interaction is called a hydrogen bond.

• Peptide Bonding between Amino Acids

  • The peptide bond is an amide bond which links amino acids together to form proteins.
  • The bond that holds together the two amino acids is a peptide bond, or a covalent chemical bond between two compounds (in this case, two amino acids).
  • The amide bond can only be broken by amide hydrolysis, where the bonds are cleaved with the addition of a water molecule.
  • The peptide bond (circled) links two amino acids together.
  • Peptide bonds are amide bonds, characterized by the presence of a carbonyl group attached to an amine.

• Covalent Bonds and Other Bonds and Interactions

  • Its biosynthesis involves breaking the triple bond of molecular nitrogen, or N2, followed by the formation of several carbon-nitrogen single and double bonds.
  • These bonds are stronger and much more common than are ionic bonds in the molecules of living organisms.
  • Thus, triple bonds are the strongest.
  • Not all bonds are ionic or covalent; weaker bonds can also form between molecules.
  • Two types of weak bonds that frequently occur are hydrogen bonds and van der Waals interactions.

• Biogeochemical Cycles

  • Sulfur, critical to the 3–D folding of proteins (as in disulfide binding), is released into the atmosphere by the burning of fossil fuels, such as coal.

• Organic Isomers

  • Structural isomers (such as butane and isobutane ) differ in the placement of their covalent bonds.
  • Geometric isomers, on the other hand, have similar placements of their covalent bonds but differ in how these bonds are made to the surrounding atoms, especially in carbon-to-carbon double bonds.
  • When the carbons are bound on the same side of the double bond, this is the cis configuration; if they are on opposite sides of the double bond, it is a trans configuration.
  • Fats with at least one double bond between carbon atoms are unsaturated fats.
  • (b) Geometric isomers have a different arrangement of atoms around a double bond.

• Hydrocarbons

  • Furthermore, individual carbon-to-carbon bonds may be single, double, or triple covalent bonds; each type of bond affects the geometry of the molecule in a specific way.
  • Double and triple bonds change the geometry of the molecule: single bonds allow rotation along the axis of the bond, whereas double bonds lead to a planar configuration and triple bonds to a linear one.
  • When carbon forms single bonds with other atoms, the shape is tetrahedral.
  • When two carbon atoms form a double bond, the shape is planar, or flat.
  • Single bonds, like those found in ethane, are able to rotate.

• Water’s States: Gas, Liquid, and Solid

  • The formation of hydrogen bonds is an important quality of liquid water that is crucial to life as we know it.
  • In liquid water, hydrogen bonds are constantly formed and broken as the water molecules slide past each other.
  • On the other hand, when the temperature of water is reduced and water freezes, the water molecules form a crystalline structure maintained by hydrogen bonding (there is not enough energy to break the hydrogen bonds).
  • Hydrogen bonding makes ice less dense than liquid water.
  • See what happens to intermolecular bonds during phase changes in this interactive.

• Chemical Reactions and Molecules

  • Chemical reactions occur when two or more atoms bond together to form molecules or when bonded atoms are broken apart.
  • When two or more atoms chemically bond with each other, the resultant chemical structure is a molecule.
  • Chemical reactions occur when two or more atoms bond together to form molecules or when bonded atoms are broken apart.
  • Two or more atoms may bond with each other to form a molecule.
  • Explore reactions in which chemical bonds are formed and broken with this model.