[Transformation of chemical energy in biomolecular systems with hydrogen bonds]. / Mekhanizm transformatsii khimicheskoi énergii v biomolekuliarnykh sistemakh s vodorodnymi sviaziami.

The mechanism underlying the excitation of the hydrogen bond with ATP hydrolysis was considered. Coulomb interactions of the proton of the hydrogen bond A-H...B with the electrical field of the covalent bond of ADP-P were calculated. It was shown that the electrical field of the covalent bond of ADP-P excites oscillations of the proton in the complex with the hydrogen bond A-H...B and displaces it from the equilibrium towards the covalent bond. The distortion of the potential curve depends on a change in the length of the covalent bond of ADP-P. Adiabatic potentials U0 and UN of the ADP-P system were calculated, which correspond to the ground and excited states of the H-bond proton. It was found that as the length of the bond of ADP-P (rho) increases, the branches of the adiabatic potential U0(rho) and UN(rho) intersect. At the intersection point, the system can transit to the branch UN(rho), which can lead to a reduction of the barrier and a break of the covalent bond of ADP-P. Presumably, this mechanism is universal for processes of transformation of the chemical energy of ATP to the energy of excited hydrogen bond, a mechanism for the maintenance of heat balance and reduction of entropy in a living organism.

[Excitation of the hydrogen bond by the energy of hydrolysis of adenosine-5'-triphosphate]. / Vozbuzhdenie vodorodnoi sviazi za schet énergii gidroliza adenozin-5'-trifosfata.

The model of muscle contraction suggested in [1] is based on the hypothesis that the first step of the conversion of chemical energy delta E (which is stored in adenosine-5'-triphosphate) is the excitation of the hydrogen bond in the actin-myosin system with a simultaneous hydrolysis of the adenosine-5'-triphosphate molecule. As a consequence, the potential barrier is decreased, and the break of the macroergic bond adenosine-5'-triphosphate-phosphate is facilitated. With the delta E value exceeding the excitation energy of the H-bond, this process represents an exothermic reaction. A simple model of this process is constructed, and its probability depending on temperature and the mutual position of the H-bond and the adenosine-5'-triphosphate molecule is estimated.

[Statistics on actin globule chains, stretched by hydrogen bonds, and the Hill law in quantum mechanics theory of muscle contraction]. / Statistika tsepochek aktinovykh globul, rastianutykh vodorodnymi sviaziami, i zakon Khilla v kvantovo-mekhanicheskoi teorii myshechnogo sokrashcheniia.

The process of sarcomere membranes approaching under the action of actin and myosin filament stretching is studied theoretically. In elaboration of previous studies it is supposed that this stretching is due to the formation of hydrogen bonds excited by the energy of ATP splitting. A possibility for the hydrogen bond breakage at different stages of contraction is considered to be the greater the more are the polymers stretched, and the larger statistical scatter in the moments of H-bonds formation at different filaments if it is supposed that sarcomere contraction occurs much slower than stretching of each separate filament. As a result, one obtains a relationship between the rate of contraction and the external force which is close to the Hill's law, and the external force efficiency of a muscle contraction and heat extraction value are related to parameters of polymers and their properties.

Excited hydrogen bonds in the molecular mechanism of muscle contraction.

The mechanism of muscle contraction is considered. The hydrolysis of an ATP molecule is assumed to produce the excitation of hydrogen bonds A--H...B between electronegative atoms A and B, which are contained in the myosin head and actin filament. This excitation energy epsilon f depends on the interatomic distance AB = R and generates the tractive force f = -delta epsilon f/delta R, that makes atoms AB approach each other. The swing of the myosin head results in macroscopic mutual displacement of actin and myosin polymers. The motion of the actin filament under the action of this force is studied. The conditions under which a considerable portion of the excitation energy converts into the potential tension energy of the actin filament are analysed, and the probability of higher muscle efficiency existence is discussed.

[Myosin head swivel in a muscular contraction model based on an hypothesis on the role of hydrogen bond excitation]. / Povorot miozinovoi golovki v modeli myshechnogo sokrashcheniia na osnove gipotezy o roli vozbuzhdennykh vodorodnykh sviazei.

A theory of muscle contraction developed by the authors in their earlier papers based on the idea of hydrogen-bond attractive force increase under excitation is modified for the model of myosin head swivel. The hydrogen bonds are supposed to be located at a hinge or near actin-myosin contact. The energy of ATP decay is transferred to the hydrogen bonds whose operation results in myosin head swivel. Equation of actin-chain globules vibrations is considered together with the equation for myosin head swivel by an angle psi approximately pi/4. Solution of the set of equations gives the time dependence of a globule displacement and of the force acting on the transverse z-membrane of the muscle fibre. Here the force and displacement in one act of ATP decay are obtained to be of the correct order of magnitude, F approximately 13 kg per 1 cm2 of muscle section and delta 1-10(-6) cm.