Electrical charges are widely utilized by the human body. The brain and
nerves experience energy bursts akin to lightning, and the majority of
biological functions rely on electrical ions moving across the membranes of
each cell in our body.
An imbalance in electrical charges on each side of a cellular membrane
makes these electrical messages conceivable in part. Up until recently,
scientists thought the membrane was crucial to causing this imbalance. But
when Stanford University researchers found that identical uneven electrical
charges may occur between microdroplets of water and air, that notion was
proven to be incorrect.
These forms of electric fields are now known to occur within and around a
different kind of cellular structure known as biological condensates,
according to Duke University researchers. These formations occur due of
variations in density, much like oil droplets floating in water. They create
compartments within the cell without a membrane's physical border.
The researchers sought to explore if small biological condensates behaved
similarly to microdroplets of water interacting with air or solid surfaces,
as had been shown in earlier study. They also sought to see whether these
imbalances triggered "redox" events involving reactive oxygen like these
other systems.
Their groundbreaking finding, which was published on April 28 in the
journal Chem, could alter the way scientists see biological chemistry. It
could also offer a hint as to how the earliest life on Earth managed to
gather the energy required for its emergence.
Yifan Dai, a Duke postdoctoral researcher working in the lab of Ashutosh
Chilkoti, the Alan L. Kaganov Distinguished Professor of Biomedical
Engineering, and Lingchong You, the James L. Meriam Distinguished Professor
of Biomedical Engineering, posed the question, "In a prebiotic environment
without enzymes to catalyze reactions, where would the energy come
from?"
"This discovery provides a plausible explanation of where the reaction
energy could have come from, just as the potential energy that is imparted
on a point charge placed in an electric field," added Dai.
Electric charges can create molecular fragments that can link together to
generate hydroxyl radicals, which have the chemical formula OH, when they
hop across different materials. These can then link together once again to
create minute but discernible quantities of hydrogen peroxide (H2O2).
The cellular membrane, one of the most crucial components of life, is the
only biological regime in which interfaces have been examined often,
according to Dai. So, if a biological condensate interface is an asymmetric
system as well, we wondered what may be occurring there.
To segregate or group together certain proteins and molecules, cells can
form biological condensates, which can either restrict or enhance the
function of those molecules and proteins. Condensates' functioning and
potential applications are just now becoming fully understood by
researchers.
The researchers had little trouble developing a test bed for their
hypothesis because the Chilkoti laboratory specialized in producing
synthetic variations of naturally occurring biological condensates. With
assistance from postdoctoral researcher Marco Messina in Christopher J.
Chang's lab at the University of California—Berkeley, they assembled the
proper formula of building blocks to produce minute condensates, and then
they added a dye to the system that lights in the presence of reactive
oxygen species.
Their instinct was correct. The presence of a hitherto unidentified
phenomena was confirmed when a solid glow first appeared from the
condensates' edges under the correct environmental circumstances. The
Marguerite Blake Wilbur Professor of Chemistry at Stanford, Richard Zare,
whose team discovered the electric behavior of water droplets, was the
second person Dai spoke with. As soon as she learned about the novel
behavior in biological systems, Zare began working on the underlying
mechanism with the group.
My graduate student, Christian Chamberlayne, and I reasoned that the same
physical principles may apply and encourage redox chemistry, such as the
creation of hydrogen peroxide molecules, as a result of earlier work on
water droplets. These results point to the significance of condensates in
cellular function.
The majority of earlier research on biomolecular condensates, according to
Chilkoti, has been on their interiors. "Yifan's finding that biomolecular
condensates seem to be universally redox-active suggests that condensates
are endowed with a critical chemical function that is essential to cells,
rather than simply evolving to carry out specific biological functions as is
commonly understood."
Dai mentions a prebiotic as an illustration of how potent its effects may
be, even if the biological consequences of this continuing interaction
within our cells are unknown. The mitochondria, or "powerhouses," of our
cells employ the same fundamental chemical mechanism to provide energy for
every activity necessary for life. But for the very earliest of life's
activities to start operating, something had to generate energy before
mitochondria or even the most basic of cells formed.
According to research, the energy came from hot springs or thermal vents in
the water. Some people have hypothesized that the same redox process that
takes place in water microdroplets was initiated by the spray of the
waves.
Why then, not condensates?
"Magic can happen when substances get tiny and the interfacial volume
becomes enormous compared to its volume," stated Dai. "I believe the
implications are significant to numerous fields."
