Snapper (left) and Hoveyda, in Hoveyda’s Merkert Chemistry Center lab. Photograph: Gary Wayne Gilbert

Just as humans have right and left hands and feet, molecules often come in two, essentially mirror-image, variations of each other. These versions often function entirely differently, but there has not been a simple, cost-effective way to produce just one or the other. When it comes to developing drugs, the implications can be profound. In a recent conversation about the phenomenon, Amir Hoveyda, holder of BC’s Joseph T. and Patricia Vanderslice Millennium Chair in Chemistry, cited the chilling example of thalidomide, a morning sickness drug prescribed to pregnant women in Europe in the 1960s. The drug included both right- and left-hand copies of its critical molecule. Unfortunately, says Hoveyda, “One hand cured morning sickness, and the other either killed the unborn infants or caused [them] serious physical damage.” Hoveyda and fellow BC chemistry professor Marc Snapper have built a molecule that may resolve this problem.

Snapper and Hoveyda started collaborating more than a dozen years ago, specializing in the construction of small molecules that promote chemical reactions. Their most recent success is a tiny ring of five atoms (they don’t have a name for it, yet) that works as a highly efficient catalyst in creating molecules of uniform chirality, or handedness. The results of their research were published in the September 7, 2006, issue of Nature.

Snapper and Hoveyda began their search for a solution to the chirality problem with a little brainstorming, listing the ideal catalyst’s potential components. They figured an amino acid base would make sense, because this building block had helped them construct other successful catalysts. A colleague in the chemistry department, Ross Kelly, had shown that hydrogen bonding is important in catalysis, so they tried to incorporate this functionality. Scott Miller, another Boston College chemist at the time, had demonstrated that a class of compounds called imidazoles are also effective in catalysts, so using them in some form seemed natural, too.

The next step: creating a molecule that had all these constituents, and actually did what they wanted it to do. Snapper and Hoveyda screened a succession of newly produced candidates through a kind of molecular casting call, testing thousands of possibilities. Through the screening, Snapper says, “You harness serendipity.”

The catalyst that emerged from the search proved to be both highly effective and versatile. It can make either the left- or right-hand version of a molecule, with a 98 percent conversion rate.

The new molecule is also relatively cheap and easy to manufacture, and incredibly small. Hoveyda says it has only one-tenth the molecular weight of the catalysts he normally works with, and one-thousandth the heft of the industrial versions used by major drug and chemical companies. All of this could translate into serious cost savings for pharmaceutical manufacturers, and lead to the development of drugs that weren’t financially viable before. “You could have the best anticancer drug in the world, but if they can’t make it in volume so they can sell it, that discovery doesn’t mean anything,” Hoveyda says. “This catalyst allows people to make one hand with high-selectivity, in an [economical] fashion.”

Since submitting their findings to Nature, Snapper and Hoveyda have vastly increased the power of the catalyst. Now it kick-starts the same reactions using far less material. “You add almost nothing, and then the reaction goes,” Hoveyda says. “It almost gets to magic.”

Gregory Mone is a contributing editor at Popular Science and the author of The Wages of Genius (2003).

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