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HARVARD TEAM BUILDS MEGA-MOLECULE

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In a feat hailed as chemistry's equivalent to conquering Mount Everest, a group of researchers at Harvard University has synthesized the largest and most complex man-made molecule.

It took a small army of chemists more than eight years to make the material, an extraordinarily poisonous compound called palytoxin carboxylic acid.

Palytoxin occurs naturally in a coral found in a single tidal pool on the island of Maui in Hawaii and is steeped in legend and superstition.

Native Hawaiians once used the coral to make a secret potion that was applied to the tips of spears, killing animals instantly even if the spear point merely scratched the animal's skin.

Chemists now recognize palytoxin as the most toxic non-protein substance known to science. But natives believed the material killed by magic. They refused to tell outsiders about the source of the poison or to lead scientists to the tidal pool. A curse supposedly awaited outsiders who tried to collect or study the coral.

A molecule of any compound - such as water, table sugar or penicillin - is the smallest particle that retains the chemical composition and properties of the compound. Compounds are composed of atoms, linked together in a three-dimensional structure by chemical bonds.

Chemists depict the composition of a molecule with a formula that shows the number of different kinds of atoms that it contains. Thus, a molecule of oxygen is O2; a molecule of phosphorous is P4; a molecule of table sugar or sucrose is C12H22O11; and a common form of penicillin has the molecular formula C16H18N2O5S.

A molecule of palytoxin is C129H223N3O54.

Like other organic compounds, palytoxin can exist in different forms, termed isomers. Isomers have the same molecular formula as the original compound but a different arrangement of atoms that gives them different chemical properties.

While some organic compounds have only two isomers, palytoxin has more than 1 sextillion - the number 10 followed by 21 zeros.

Palytoxin was synthesized by Yoshito Kishi and a group of graduate students and post-doctoral fellows who worked in his Harvard laboratory.

Scientists say that some of the compounds show promise in the treatment of a variety of common diseases, including high blood pressure, asthma, glaucoma, and certain forms of cancer.