Scientists
at the University of Southern California and Lawrence Berkeley National Lab have discovered a new route
by which a proton (a hydrogen atom that lost its electron) can move from
one molecule to another—a basic component of countless chemical and
biological reactions.
“This
is a radically new way by which proton transfer may occur,” said Anna
Krylov, professor of chemistry at the USC Dornsife College of Letters,
Arts and Sciences. Krylov is a co-corresponding author of a paper on the
new process that was published online by Nature Chemistry on March 18.
Krylov
and her colleagues demonstrated that protons are not obligated to
travel along hydrogen bonds, as previously believed. The finding
suggests that protons may move efficiently in stacked systems of
molecules, which are common in plant biomass, membranes, DNA and
elsewhere.
Armed
with the new knowledge, scientists may be able to better understand
chemical reactions involving catalysts, how biomass (plant material) can
be used as a renewable fuel source, how melanin (which causes skin
pigmentation) protects our bodies from the sun’s rays, and damage to
DNA.
“By
better understanding how these processes operate at molecular level,
scientists will be able to design new catalysts, better fuels, and more
efficient drugs,” Krylov said.
Hydrogen
atoms are often shared between two molecules, forming a so-called
hydrogen bond. This bond determines structures and properties of
everything from liquid water to the DNA double helix and proteins.
Hydrogen
bonds also serve as pathways by which protons may travel from one
molecule to another, like a road between two houses. But what happens if
there’s no road?
To
find out, Krylov and fellow corresponding author Ahmed Musahid of the
Lawrence Berkeley National Lab created a system in which two molecules
were stacked on top of each other, without hydrogen bonds between them.
Then they ionized one of the molecules to coax a proton to move from one
place to another.
Ahmed
and Krylov discovered that when there’s no straight road between the
two houses, the houses (molecules) can rearrange themselves so that
their front doors are close together. In that way, the proton can travel
from one to the other with no hydrogen bond—and with little energy.
Then the molecules return to their original positions.
“We’ve come up with the picture of a new process,” Krylov said.
This
research was performed under the auspices of the iOpenShell Center and
supported by the US Department of Energy, the Defense Threat Reduction
Agency, and the National Science Foundation.
Source: University of Southern California
