For Penn scientist Les Dutton, physics offers a simple, elegant, and potentially useful way of understanding what makes life alive — distinguishing creatures like us from inanimate matter.
“There’s nothing magical about it,” he said in an interview earlier this week.
Dutton’s work at the intersection of physics, chemistry and biology has led him to discover a distinct signature of life in the way biological molecules transfer electrons, the carriers of electricity.
“It all started with Benjamin Franklin,” said Dutton. “He recognized the power of electricity.”
At a ceremony tonight, Dutton will receive The Scott Medal, a prestigious $12,000 award inspired by Benjamin Franklin’s spirit of invention. The award was endowed by Scottish chemist and pharmacist John Scott and has been given out in Philadelphia since 1822. Past recipients include Marie Curie, Thomas Edison and the Wright brothers.
Two other winners this year are Scott Adzick, of the Children’s Hospital of Philadelphia, for his advances in fetal surgery, and Robert L. Brent, former Chairman of Pediatrics at Thomas Jefferson University, for his research on birth defects.
Dutton, 72, who is a professor of biochemistry and biophysics, originally trained in physics and chemistry, later taking an interest in biochemistry. At the nexus of these fields, he found a very different understanding of the way life works.
Only ‘adequate,’ not exquisite
The scientific community long ago abandoned the ancient belief in vitalism — the notion that life was made from some fundamentally different substance or ran on a unique form of energy. More recently, the prevailing view has dictated that the molecular machinery running living things is exquisitely designed — not by a deity, necessarily, but by millions of years of evolution. In that view, he said, life was distinguished by the exquisite complexity of the proteins that went about capturing energy from food or sunlight, or carrying out various other essential jobs.
In Dutton’s view, our molecular make-up isn’t exquisite — it’s only adequate. What distinguishes the realm of the living is the way electrons move from one protein to another — processes called oxidation or reduction, depending on whether the electron is coming or going. The selection committee for the Scott Award officially recognized his work in, “the elementary process of oxidation-reduction and the diverse biological events coupled t it.”
Oxidation-reduction happens in living and non-living matter. The difference, he said, becomes clear when you bring in the area of physics known as quantum mechanics. In non-quantum, or classical physics, electrons need a minimum amount of energy to leap from one molecule to another, but quantum mechanics shows how electrons can borrow the energy to get from one point to another through a process called tunneling. “Tunneling in biology is a description of everything there is,” he said.
Physicists can describe a tunneling event with a few simple parameters, he said — including vibration, free energy and the distances over which electrons are likely to tunnel from one molecule to another. In non-living matter there are huge numbers of possible values for these parameters, but living matter limits them to a narrow range. That narrowing is the work of natural selection, he said, as it shaped the chemical and physical traits that distinguish life on Earth.
“We turned [the understanding of this biological process] from something that was immensely complex to something that was simple” he said. “Nature selected the quantum mechanical parameters that were useful.” He credits his two colleagues, Chris Moser and Marilyn Gunner, for making this new understanding possible.
I wondered how this new understanding might influence inquiries into the origin of life, or the question of whether we’re alone. On the same day I came to interview Dutton at Penn, the New York Times ran an opinion piece by physicist Paul Davies on both of those topics. Davies wrote that the news about NASA finding many habitable planets was “hype” because life may be very difficult to get started. Davies noted that scientist used to think life originated through a very unlikely chain of chemical events.
But that’s changed. Dutton said his work doesn’t yet tell us anything about how life originated but he doesn’t see why life wouldn’t be ubiquitous. “There’s no magic step between chemistry and biology.”
Taking away the magic might seem disheartening, but that is what science does, thus allowing humans to harness and control the natural world in new ways. For Dutton, the fact that proteins are not so perfectly exquisite opens the possibility that we could invent new ones. And so, he said, he’s currently designing new proteins in collaboration with Penn’s William DeGrado. These would not be modified mimics of existing biological molecules, but novel structures, designed with a specific task in mind.
One application is artificial blood, he said, which could be made compatible with any human blood type. Artificial blood could even be engineered to withstand extreme temperatures, or work in high concentrations of carbon monoxide.
Once people thought blood proteins called globins would be hard to improve on. “Everyone thought globin folding was exquisitely designed. They thought three billion years of evolution achieved perfection.” He said. “What we found was that it was three billion years of one mistake after another.”
There are all kinds of other applications for designer proteins, he said, from coaxing algae to make hydrogen for fuel to helping plants grow without fertilizer.
“It’s all fantasy,” he said. Then he picked his iPhone up from his desk. “A few years ago this was all fantasy too.” He mused on why Ben Franklin never invented an iPhone. It was the materials — Franklin didn’t know about grapheme or modern semiconductors.
Now, he said, we’re on the verge of a new class of materials — inspired by biological molecules but more efficient. And from them, tomorrow’s Ben Franklins will find uses yet unimagined.