Tertiary structure
Interactions of the side chains with one another contribute to the tertiary structure (overall shape) of the polypeptide.
Hydrogen-bonding between H attached to N or O and
Induced dipole attractions between nonpolar side chains
Ionic attractions between electrically charged side chains having opposite charges
Disulfide bridges formed by reaction of an oxidant with the side chains on cysteines
Hydrogen-bonding between H attached to N or O and
the O of C=O or OH in another side chain.
N in another side chain.
N in another side chain.
Induced dipole attractions between nonpolar side chainsWhile nonpolar side chains do not have permanent dipoles due to differences in electron density, the electron density of a nonpolar side chain can shift when approached by the electron cloud of another nonpolar side chain. This introduces a temporary dipole in both.
Move your mouse over the image at the right to see the effect of this.Temporary dipoles are changing all of the time, but stay in step long enough so that they result in a significant attractive force.
Move your mouse over the image at the right to see the effect of this.Temporary dipoles are changing all of the time, but stay in step long enough so that they result in a significant attractive force.
Ionic attractions between electrically charged side chains having opposite charges
These are stronger than hydrogen bonds or hydrophobic interactions because each component has a full (not partial) charge
Disulfide bridges formed by reaction of an oxidant with the side chains on cysteines
2 -CH2SH + oxidant → -CH2S-SCH2- + 2H-oxidant
The attractive force in this case is a covalent bond. Covalent bonds are stronger attractive forces than either hydrogen-bonds or induced dipole attractions.