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Fig. 11.35 The conformon mechanism of chemical-to-mechanical energy transduction in biology
proposed in Ji (1974b) which was supported by the single-molecule mechanical measurements
made by Ishijima et al. (1998; Ishii and Yanagida 2007)
Figure
11.35
supported by the empirical data in Fig.
11.34
thus substantiates the
following generalizations:
1. Motor enzymes are molecular machines that carry out chemical-to-mechanical
(i.e., “chemo-mechanical”) energy conversion/transduction at the microscopic
level at physiological
temperatures, similar to combustion engines at
the
macroscopic level at high temperature.
2. Motor enzymes convert chemical energy first to the intermediate form of
conformational energy known as
conformons
before they are converted to
mechanical forces acting on their environment to do work.
If this analysis turns out to be correct, it could be concluded that the conformon
concept embodies the most fundamental characteristics of enzymes (both simple
enzymes and molecular motors) at the microscopic level providing a theoretical
foundation for single-molecule mechanics (Xie 2001; Ishii and Yanagida 2007;
Deniz et al. 2008).
11.4.2 Static/Stationary versus Dynamic/Mobile Conformons
In Sect.
11.3
, the single-molecule enzymological data of Lu et al. (1998), namely,
the waiting time distribution of cholesterol oxidase (see Fig.
11.24
) were analyzed
on the basis of the postulated analogy between the
blackbody radiation
and
enzymic catalysis
. The net result of this analysis was the conclusion that the
ground-state cholesterol oxidase (and presumably those of enzymes in general)
contains a set of
conformons
with different free energy contents (See Fig.
11.28
).
In Sect.
11.4.1
, the single-molecule mechanics data on the actomyosin system
measured by Ishijima et al. (1998) were found to be consistent with the
predictions made by the
conformon
model of muscle contraction proposed in
Ji (1974b). In both analyses, the concept of the
conformon
played a key role, but
with some difference. In cholesterol oxidase, the conformons are postulated to be
present even before the catalysis takes place, most likely due to the
endogenous
conformational strains
introduced into the protein as it is synthesized on the
ribosome one amino acid at a time and folded into a globule before the last
amino acid is added (see Klonowski and Klonowska 1982 for a related discus-
sion). In contrast, the conformons postulated to be generated within the myosin
molecule during muscle contraction are the result of ATP hydrolysis and are not
thought to remain stored in myosin long, before they are used up in doing
