Chemistry Reference
In-Depth Information
2
Single Molecule Study for Elucidating the Mechanism Used
by Biosystems to Utilize Thermal Fluctuations
Toshio Yanagida
2.1
Introduction
2.1.1
Differences between Man-Made and Biological Molecular Machines
To ful ll their functions, biomolecules assemble to formmolecular machines which
play essential roles in cellular functions such as cell signaling, energy transduction,
motion, and DNA duplication. Collaboration between these machines regulates the
activity of biological systems (Figure 2.1a). Molecular machines are complex ma-
chines whose functions are not analogous to arti cial machines. What are the
essential differences between biological molecular machines and man-made ma-
chines? Biological molecularmachines are nanometers in size, are dynamic and have
a soft structure. In addition, their input energy is not much greater than the average
thermal energy (k B T) meaning that they function under strong thermal agitation.
This is in contrast to man-made machines, which require an energy input that is
much higher than thermal energy and thus avoids the effect of thermal noise. Thus,
the operations of biological and man-made machines are vastly different. For
example, the operation time of electronic processors in a computer is nanoseconds,
while that of molecular machines in the brain is milliseconds, i.e. the operation time
of molecular machines is millions-fold slower. Furthermore, the accuracy of molec-
ular machines is far poorer than that of electronic processors. But such slow and
inaccurate molecular machines can assemble to form wonderful systems such as
muscle and brain, functions that cannot be duplicated by man-made machines
(Figure 2.1b).
Because of this, molecular machines likely operate on a principle essentially
different from man-made machines. The aim of our research is to illuminate the
essential engineering principle behind the flexible and adaptive nature of biological
systems by understanding the unique operations of molecular machines.
 
Search WWH ::




Custom Search