Chemistry and Health: Fooled by Molecular Shape

• In the tongue, specialized cells act as highly sensitive and specific molecular detectors. The main basis for this discrimination is the molecule’s shape.
• The surface of a taste cell contains specialized protein molecules called taste receptors. Each molecule that we can taste fits snugly into a special pocket on the taste receptor protein called the active site.
• Artificial sweeteners taste sweet because they fit into the receptor pocket that normally binds sucrose.
• Both aspartame and saccharin bind to the active site in the protein more strongly than sugar does.
• For this reason, artificial sweeteners are “sweeter than sugar.”
• It takes 200 times as much sucrose as aspartame to trigger the same amount of nerve signal transmission from taste cells.
• The ability of scientists to determine the shapes of key biological molecules is largely responsible for the revolution in biology that has occurred over the last 50 years.