Secondary structures like α-helices are due to interaction between the H of NH and the O of C=O from different amino acids in the backbone of the protein.
Interactions of amino acid side chains with one another contribute to the tertiary structure (overall shape) of the polypeptide.
Hydrogen-bonding between H attached to N or O in one amino acid side chain and and the N and O of another amino acid side chain.
Ionic attractions between electrically charged side chains having opposite charges
Hydrophobic attractions between nonpolar side chains Disulfide bridges formed by reaction of an oxidant with the side chains on cysteines.
Interactions of amino acid side chains with one another contribute to the tertiary structure (overall shape) of the polypeptide.
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
Hydrophobic attractions between nonpolar side chains
Nonpolar side chains do not have permanent dipoles. But temporary dipole result when the electron clouds of a nonpolar side chains approach one another.
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.
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 hydrophobic attractions.