Hypothesis
on the role of liganded states of proteins
in energy transducing systems
Bennun, A.
(INTRODUCTION
FRAGMENT)
In energy transducing
systems the direction of energy transfer is proposed to be
maintained by the synchro¬nized turnovers of the conformational
change of one protein coupling up to affect another. Catalysis
by those systems implies, therefore, that under new space
restrictions the groups of the transducing enzyme increase
and decrease reactivity between themselves, with activatory
and/or inhibitory ligands (H+, H2O, metals, etc.) and with
the electron shells of the reactant molecules. The exergonic
reaction-dependent turnover of the forms of the enzyme within
the transition complexes would be maintained, therefore, under
asymmetric phase angles of conformational-dependent reactivity
that would effectively restrict the microscopic reversibility
of transducing systems. Some well known reactions, such as
hemoglobin's Bohr effect, can be used to illustrate that microscopic
(molecular) interactions subject to thermodynamic equilibria
laws may similarly participate as driving forces in energy
transducing systems. This would allow the thermodynamic description
of the role of proton translocation as that of a modificatory
force of the structural parameters of proteins. Similarly,
the relationship between the liganded states of hemoglobin
and its change in conformation has been used to develop an
illustrative model relating changes in oxido-reduction of
electron carriers to induced-fit effects leading to a sequence
of ATPase forms in transition complexes which become stabilized
as high energy intermediates under the constraints im¬posed
by the membrane of energy transducing organelles.
Biosytems, 7, (1975), 230-244