Study Of Directional Movement Of Physical Mechanism Of Molecular Motors

In recent years, with the development of new technology, such as optical tweezers technique, sequence analysis, x-ray crystallographer and fluorophore image technique, greet progress has been made in the molecular biology, especially in the studies of the structure and motor motility. Till now, there are hundreds of motors have been found. Although they are different in structure, they all can move along filament or microtubule toward minus end or plus end when they consume ATP or ATP analog. According to the difference of their manners of movement, they are generally classified into two classes: one is linear motors including myosin, kinesin, dynesin, the other is rotary motors, such as Fl-ATP ase and the bacterical flagellar motor. In this article, I will simply introduce some kinds of motors well known by people and discuss their structure, motility model and their importance in living cells. In recent findings, many experiment results of myosin and kinesin in Science and Nature, we find each motor of any kind has a catalytic core that binding ATP and track in its domain and neck linker, which closely connected with dynamic motion. Studying the structure of molecular motor enable us to understand its mechanism of directed motion.Various theories have been proposed to explain the experimental results on Kinesin motility. They can be grouped into two categories. One approach uses a multistate kinetic description and postulates the motor steps through a sequence of discrete chemical states. In theories of second category a motor is viewed as one or a set of Brownian particle(s) moving in a one-dimensional periodical potential representing the interaction between a motor and a track. We will introduce two typical models in this article: one is the directed movement of the Brownian particle generated by fluctuating potentials, the other is the Brownian motor possessing internal degree of freedom, in which the track consists of a line of smallidentical ball, motor and its track are view as dipoles, and the dominant interaction between them is electric. Supposing that the change of the interaction is represented by the rotation of its internal degree continuousely , we can evaluate the current explicitly by means of matrix continued fraction technique.We have constructed a simple model for two headed molecular motors in which we use two transition parameters to substitute the periodical change of a two-state flashing potential. The behavior of the current depends sensitively on system parameters and exhibits several novel features.What relevance might these results have to real motors? General speaking, they coincide with some aspects of those experiments published in Science or Nature. As we have studied molecular motors with different neck length move in different directions, but one class of kinesins (typified by Drosophila Ncd) and one class of myosins (myosin VI) travel in the opposite direction to most kinesins and myosins.