Research into a 'breakwater' that helps electron =
transfer=20
published in PNAS
![3DPNAS](3D"http://people.ucalgary.ca/~ria/2010/June2010/images/cover_final_gr=) An interdisciplinary team of =
researchers=20
at the University of Calgary has found that amino acid =
residues form a type of barrier to help in the process =
of=20
electron transfer between proteins.
Electron transfer between proteins is the =
cornerstone of=20
biological energy transfer. Every life-form uses this =
process=20
to convert food or sunlight into chemical energy.
The U of C researchers found that the electron =
travels over=20
a bridge made of a water molecule, while residues on =
one of=20
the proteins form a sort of 'molecular breakwater' to =
keep=20
other water molecules away while the electron travels =
across=20
the bridge.
"You don't want too many (water molecules around =
the=20
bridge) because it gets too crowded and they're all =
bumping=20
into each other and you can't get one to fit at just =
the right=20
position and the right angle (for the bridge) for any =
length=20
of time," says PhD student Nathan Babcock. "It's like =
being on=20
a crowded subway where you can=E2=80=99t get =
comfortable."
In artificial mutations with a faulty breakwater, =
the water=20
bridge is disrupted and the rate of electron transfer =
is=20
markedly reduced, he says.
Babcock and Aurelien de la Lande, now at the CNRS =
in=20
France, Jan Rezac, now at the Czech Academy of =
Science, Barry=20
Sanders, iCORE Chair of Quantum Information Science at =
U of C=20
and Dennis Salahub, Director of the Institute for=20
Biocomplexity and Informatics and Professor in the =
Department=20
of Chemistry at U of C co-authored a paper, Surface =
residues dynamically organize water bridges to enhance =
electron transfer between proteins that has been =
published=20
in the prestigious journal, Proceedings of the =
National=20
Academy of Science (PNAS).
"This raises the bar for biomolecular modeling", =
says=20
Salahub. "At a fundamental level, it is by far the =
most=20
detailed insight that has been obtained for the =
dynamic role=20
of water in this kind of electron transfer, or for =
that matter=20
any biochemical reaction."
Using the CHARMM molecular simulation computer =
program, the=20
research team examined a 40 nanosecond period of =
electronic=20
coupling of the proteins methylamine dehydrogenase and =
amicyanin from the bacterium Paracoccus =
denitrificans.
"This is fundamental research but you can imagine =
how=20
studies like this can be applied to various =
genetically=20
modified organisms, and if you can gain control over =
some, you=20
can use it to either speed up or slow down a =
particular=20
reaction," says Salahub.
He says the work was made possible with the =
collaboration=20
of two of the U of C's interdisciplinary research =
institutes;=20
the Institute for Biocomplexity and Informatics (IBI) =
and the=20
Institute for Quantum Information Science (IQIS).
Babcock, whose background is in quantum information =
theory,=20
was pleased to do research at the union of these two=20
disciplines. "When you think of quantum mechanics, =
usually=20
you=E2=80=99re thinking solid state semi conductors, =
atoms trapped=20
with lasers, etc. It's usually cold laboratory stuff, =
not warm=20
globby biological stuff," says the PhD student.
"I think the union of biology and quantum mechanics =
is=20
very, very exciting."
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