Biology Reference
In-Depth Information
Process
8.11
, which finally drives the free energy-requiring desorption of ATP from
F
1
in Process
8.12
(Boyer 2002).
ETC
{
corresponds to the Franck-Condon state
and
ETC
* is the energized state harboring real conformons symbolized by the
superscript *. In other words, the superscripts
{
and * denote the
virtual
and
real
conformons
, respectively.
Virtual conformons are thermally derived and hence
are derived from free energy-releasing processes such as substrate binding or
chemical reactions and hence can be utilized to do work. The conformon theory
of molecular machines (Sect.
8.4
) provides a reasonable and realistic mechanism
for converting virtual conformons to real conformons based on the generalize
Franck-Condon principle (Sect.
2.2.3
).
According to the conformon hypothesis of oxidative phosphorylation, every
key step in oxidative phosphorylation occurs inside the inner mitochondrial mem-
brane and at no time is there any transmembrane proton gradient generated:
No
chemiosmosis is required for oxidative phosphorylation
. However, the free energy
stored in
TRU* can
be utilized to generate
transmembrane proton gradient,
if
necessary, given appropriate experimental or physiological conditions, when the
energy is transferred from
TRU
* to a hypothetical enzymic unit called the “proton
transfer complex,”
PTC
, yet to be discovered (Green and Ji 1972a, b; Ji 1979,
1985a, b). It has been postulated that the proton gradient formed across the inner
mitochondrial membrane often observed under artificial experimental conditions
is needed not for oxidative phosphorylation as assumed by Mitchell (1961, 1968)
but (1) mainly for the
communication between mitochondria and the cytosol
for
the purpose of monitoring the ATP needs of the cell and (2) possibly for
synthesizing ATP driven by the proton gradient generated by anaerobic glycolysis
during anoxia (lack of oxygen) or ischemia (lack of blood flow) (Ji 1991, pp.
60-61). It is further postulated that when this mechanism of proton-mediated
intracellular communication breaks down due to the permeability transition of the
inner mitochondrial membrane, the cell undergoes a programmed cell death or
“apoptosis” (Crompton 1999).
8.2 The Generalized Franck-Condon-Principle-Based
Mechanism of Conformon Generation
In Process
8.10
above, it was assumed that a part of the free energy released from
the oxidation of NADH was stored in the enzyme system,
ETC
, that catalyzes the
exergonic reaction. One plausible mechanism that can accomplish this
chemical-to-
mechanical energy conversion
is schematically shown in Fig.
8.1
. In passing, it
should be noted that the
chemical-to-mechanical energy conversion
is synonymous
with the
chemical reaction-induced force generation
, because
force
and
energy
(or
work) are related through the Second Law of Newtonian mechanics as indicated
