In globular proteins such as enzymes,
the long chain of amino acids becomes folded into a three-dimensional functional
shape or tertiary structure. This is because certain amino acids with sulfhydryl
or SH groups form disulfide (S-S) bonds with other amino acids in the same
chain. Other interactions between R groups of amino acids such as hydrogen
bonds, ionic bonds, covalent bonds, and hydrophobic interactions also contribute
to the tertiary structure.
