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While the folded protein affects up to 1,000 water molecules in its environment, the partly unfolded protein has a lesser affect on water. (Credit: Image courtesy of Ruhr-Universität-Bochum) (Click image to enlarge) |
Scientists from Bochum, Illinois, and Nevada were able to prove with
terahertz (THz) spectroscopy that proteins do modify water molecules in
their environment to a long range extent: The water molecules, which
generally move around like disco dancers in their collective network
motions behave more like in a neat minuet under protein influence.
The group by Prof. Dr. Martina Havenith-Newen (Physical Chemistry II
Dpt., RUB) managed to find out more about the rules of this dance. They
could show that protein folding changes the dancing steps of water. A
partly unfolded protein will affect water molecules within the
dynamical hydration shell to a much less extent than a folded one does.
The higher the flexibility of the protein, the less affected is the
water.
In water, weak bonds between two adjacent water molecules, referred
to as the hydrogen bridge bonds, are continuously opening and closing:
this happens on average every 1.3 pico seconds (one pico second = 10
power -12 seconds). “Even small concentrations of proteins in water
lead to measurable changes in collective movements“, Prof.
Havenith-Newen explains the results of previous studies with THz
spectroscopy.
Folding is the Important Thing
While the folded protein affects up to 1,000 water molecules in its
environment, this is only true for the partly unfolded protein to a
small extent. If one modifies some parts of the protein through
mutation, the effect is less remarkable. These observations were now
made by the scientific teams of Prof. Havenith-Newen, Prof. Dr. Martin
Gruebele, and Prof. Dr. David M. Leitner from RUB, the University of
Illinois and the University of Nevada, respectively.
“This shows that water in the environment of folded proteins is
different from that in the environment of an unfolded protein“, Prof.
Havenith-Newen concludes. ”This will further support the hypothesis
that protein and water are not independent of each other and do
influence each other – an effect which has been considered decisive for
protein folding, and which may be highly important for protein
functions.“
New, Highly Precise Method of Proof
THz spectroscopy is a new, especially sensitive method of observing
fast water network movement in the close vicinity of proteins with the
THz frequencies ranging between microwave and infrared frequencies.
Particularly strong THz laser radiation sources lasers, which has been
used in chemistry for the first time by RUB, facilitates the
observation of proteins in their natural environment during their fast
dance with water molecules.
Journal reference: S. Ebbinghaus, S. J. Kim, M. Heyden, X. Yu, M.
Gruebele, D.M. Leitner, and M. Havenith: Protein sequence- and
pH-dependent hydration probed by Terahertz spectroscopy. In: Journal of
the American Chemical Society, ASAP Article 10.1021/ja0746520
S0002-7863(07)04652-5, Web Release Date: February 5, 2008,
http://pubs.acs.org/cgi-bin/abstract.cgi/jacsat/asap/abs/ja0746520.html
Funding was provided by the Human Frontier Science Programme.
Scientists from Bochum, Illinois, and Nevada were able to prove with
terahertz (THz) spectroscopy that proteins do modify water molecules in
their environment to a long range extent: The water molecules, which
generally move around like disco dancers in their collective network
motions behave more like in a neat minuet under protein influence.
The group by Prof. Dr. Martina Havenith-Newen (Physical Chemistry II
Dpt., RUB) managed to find out more about the rules of this dance. They
could show that protein folding changes the dancing steps of water. A
partly unfolded protein will affect water molecules within the
dynamical hydration shell to a much less extent than a folded one does.
The higher the flexibility of the protein, the less affected is the
water.
In water, weak bonds between two adjacent water molecules, referred
to as the hydrogen bridge bonds, are continuously opening and closing:
this happens on average every 1.3 pico seconds (one pico second = 10
power -12 seconds). “Even small concentrations of proteins in water
lead to measurable changes in collective movements“, Prof.
Havenith-Newen explains the results of previous studies with THz
spectroscopy.
Folding is the Important Thing
While the folded protein affects up to 1,000 water molecules in its
environment, this is only true for the partly unfolded protein to a
small extent. If one modifies some parts of the protein through
mutation, the effect is less remarkable. These observations were now
made by the scientific teams of Prof. Havenith-Newen, Prof. Dr. Martin
Gruebele, and Prof. Dr. David M. Leitner from RUB, the University of
Illinois and the University of Nevada, respectively.
“This shows that water in the environment of folded proteins is
different from that in the environment of an unfolded protein“, Prof.
Havenith-Newen concludes. ”This will further support the hypothesis
that protein and water are not independent of each other and do
influence each other – an effect which has been considered decisive for
protein folding, and which may be highly important for protein
functions.“
New, Highly Precise Method of Proof
THz spectroscopy is a new, especially sensitive method of observing
fast water network movement in the close vicinity of proteins with the
THz frequencies ranging between microwave and infrared frequencies.
Particularly strong THz laser radiation sources lasers, which has been
used in chemistry for the first time by RUB, facilitates the
observation of proteins in their natural environment during their fast
dance with water molecules.
Journal reference: S. Ebbinghaus, S. J. Kim, M. Heyden, X. Yu, M.
Gruebele, D.M. Leitner, and M. Havenith: Protein sequence- and
pH-dependent hydration probed by Terahertz spectroscopy. In: Journal of
the American Chemical Society, ASAP Article 10.1021/ja0746520
S0002-7863(07)04652-5, Web Release Date: February 5, 2008,
http://pubs.acs.org/cgi-bin/abstract.cgi/jacsat/asap/abs/ja0746520.html
Funding was provided by the Human Frontier Science Programme.
Source : Ruhr-Universität-Bochum. February 2008.
