Brownian Ratchet Models of Molecular Motors

Abstract

Brownian ratchet theory refers to the phenomenon that nonequilibrium fluctuations in an isothermal medium and anisotropic system can induce mechanical force and motion. This concept of noise-induced transport has motivated an abundance of theoretical and applied research. One of the exciting applications of the ratchet theory lies in the possible explanation of the operating mode of biological molecular motors. Biomolecular motors are proteins able of converting chemical energy into mechanical motion and force. Because of their dimension, the many small parts that make up molecular motors must operate at energies only a few times greater than those of the thermal baths. The description of molecular motors must be stochastic in nature. Here, we review the theoretical concepts of the Brownian ratchet theory and its possible link to the operation of biomolecular motors. We illustrate the principle of the ratchet theory with models of two molecular motors: a rotary motor (F0F1ATP synthase) and a linear motor (myosin II).

How depolymerization can promote polymerization: the case of actin and profilin

“…The advantage of such a mechanism is the removal of certain time constraints that limited the accuracy of models of biological systems based on the prior paradigm. Brownian ratchet theory has recently been applied in attempts to describe a wide range of biologic processes including myosin motors, (53) protein translocations through the membrane, (54,55) movement of mRNA-bound t-RNA through the ribosome, (56) membrane motion during a phagocytosis-like process in bacteria, (57,58) diffusion of collagenase on collagen fibrils, (59) coated vesicle formation, (60) chromosome transport, (61) RNA polymerase movement, (62) actin-based bacterium movement, and lamellipodial and filopodial protrusion of a migrating cell. (63)(64)(65)(66)(67) Recently a new mechanism has been developed for the effect of profilin on A c (28) which is related to the Brownian ratchet theory through the fact that both are based on the same general physical principle for indirect energy coupling.…”

“…(63)(64)(65)(66)(67) Recently a new mechanism has been developed for the effect of profilin on A c (28) which is related to the Brownian ratchet theory through the fact that both are based on the same general physical principle for indirect energy coupling. (53) The new model although does not calculate the displacement or force production but rather provides an explanation of how profilin could modulate the energy coupling already existing in its absence and shows how chemical energy of ATP hydrolysis could be indirectly coupled to the chemical energy of actin polymerization through a fluctuation-based process of exchange diffusion. (28) The process of exchange diffusion…”

A Methodology to Study the Electromagnetic Behavior of a Cryogenic Metallic System Used to Control the Ratchet Effect

“…In order to generate the Ratchet transport in these samples, three conditions have to be satisfied. First condition is the presence of spatial inversion asymmetry in the studied samples [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. This can be achieved by patterning a periodic array of semidiscs shaped nanoantidots in a hexagonal lattice (using electron beam lithography) [2][3][4][5][6].…”

“…For many years, the Ratchet phenomenon has been observed in various systems characterized by asymmetry and non-equilibrium including: (i) the biological molecular transport in systems such as proteins and bacteria [13]; (ii) the motion of liquid droplets on hot metallic asymmetrical surfaces [14] and (iii) semiconductor devices [15].…”

Protein Linear Molecular Motor‐Powered Nanodevices

“…These devices are hybrids: consisting of naturally evolved protein motors, biochemically interfaced and housed in glass or polymeric microstructures, possibly with external (fluidic or EM) control of motility. The motivation for such devices stems from the high chemical-to-mechanical energy efficiency these motors can attain [49,50] and their naturally occurring, small-scale, bottom-up fabrication.…”