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Life is Sweet

Picture of woman made from candy

Photo credits, from top: Linda A. Cicero/Stanford News Service; Jeremy M. Baskin and Scott T. Laughlin

By Sam Scott

Carolyn Bertozzi’s introduction to the sugars that coat the outsides of our cells was short and, well, sweet. She was taking a biology course early in her undergraduate career at Harvard when the professor likened a cell to a peanut M&M. Both, he told the students, were encased in a sugar coating. At this moment in the mid-’80s, a TV-obsessed America couldn’t help but know about the candy’s sugary exterior. “The milk chocolate melts in your mouth, not in your hand” was one of the era’s most familiar commercial jingles. But why our cells were similarly dressed up was a murkier matter even to Bertozzi’s professor. Perhaps their sugary exteriors also provided a protective barrier, he told the class. No one knew the extent of it.

As first impressions go, it wasn’t much. Bertozzi wrote down the analogy and moved on with no reason to think she had just gotten the first taste of the realm of research that would make her a scientific superstar: a MacArthur “genius” at 32, the first woman to win the $500,000 Lemelson-MIT Prize, and a perennial presence in future-Nobel-laureate guessing games. It was later, in graduate school at Cal, that Bertozzi would become steeped in glycoscience. 

Over the ensuing decades, the M&M metaphor has stayed with Bertozzi—a chemical biologist who directs Stanford’s Chemistry, Engineering and Medicine for Human Health institute, aka ChEM-H—as a way to illustrate a still underappreciated fact: Our cells—like every cell on Earth—are shrouded with sugars as surely as the famous colorful confections, and yet we know little about our own candy coating. Bertozzi has spent her career trying to understand, explore and exploit the mysterious, apparently indispensable nature of these sugars, with implications for how we treat everything from common cancers to rare genetic syndromes. 

‘If we’re successful, history will look back on this field and wonder how people could have been so blind. But that’s how it is.’