Identify the true statements regarding disulfide bridges (disulfide bonds). Include all that apply.

a. Disulfide bridges are important to primary and tertiary structure, not quaternary

b. Disulfide bridges have a stabilizing effect on proteins

c. A disulfide bridge forms between two cysteine residues.

d. Disulfide bridges can exist between two amino acid residues on the same chain.

e. Disulfide bridges are formed by an irreversible oxidation reaction.