Final answer:
The irregular loops connecting the polypeptide backbone stabilize themselves through hydrogen bonding, disulfide linkages, and electrostatic interactions.
Step-by-step explanation:
The irregular loops connecting the polypeptide backbone stabilize themselves through hydrogen bonding, disulfide linkages, and electrostatic interactions. Hydrogen bonding occurs between a highly electronegative atom and a hydrogen atom in another molecule. Disulfide linkages form when sulfur atoms in cysteine amino acid units are oxidized and linked together. Electrostatic interactions result from the attraction between positively and negatively charged side chains of amino acids.