Page 62 - The Miracle of Protein

60 THE MIRACLE OF PROTEIN

After proteins assume their secondary structures with H bonds,
Van der Waals forces cause them to fold into their tertiary structure.

The three-dimensional form of the protein is stabilized and kept
from dissolving in the extracellular environment.
Experiments have shown these bonds to be of crucial im-
portance. Every one of them permits the protein molecule to
bend in exactly the desired manner in various sites along its

length. For example, disulphide bonds form only in specific re-
gions of the protein molecule, but permit a particular bending
in those regions to the exact extent required. In a similar way,
other forces act on amino acid regions to cause certain sections
of the chain to approach one another, or to move away. The ab-
sence of any one of these necessary folds and curves will render
the protein useless.