Abstracts » Zoology and wildlife conservation

Unbinding force of a single motor molecule of muscle measured using optical tweezers

Article Abstract:

Measurement of the unbinding force between an actin movement and a single motor molecule of muscle, myosin, showed that the unbinding force was independent of the number of measurements and the direction of the imposed loads within the range of plus or minus 90 degrees celsius, with the average unbinding force of 9.2 plus or minus 4.4 pN. The unbinding and rebinding between proteins and their substrates form the main components of sliding movement in the absence of ATP. These results suggested that unbinding occurs sequentially at the molecular interface. This phenomenon is the inherent property of motor molecules.

Muscles, Protein binding, Molecules

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Regulation of DNA-replication origins during cell-cycle progression

Article Abstract:

Chromosome VI of Saccharomyces cerevisiae has been shown to contain nine origins of DNA replication differing in initiation frequency, and replicating sequentially during the cell-cycle S-phase. There are also links between activation of the multiple origins and regulation of S-phase progress. The effects of methyl methane sulphonate (MMS), a DNA-damaging agent were studied, and it was found that MMS slows S-phase progression, as well as selectively blocking initiation from late origins.

DNA, Observations, Cell cycle, Saccharomyces

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Right-handed rotation of an actin filament in an in vitro motile system

Article Abstract:

Actin filaments together with myosin allow muscles to contract by forming a superhelix whose left-handed coil indicates that the sliding force acting on it has a right-handed torque. A new in vitro motile system using undissociable heavy meromyosin to trace the movements of actin filaments was devised to elucidate actin's role in muscular contraction. The deduced right-handed torque accounts for other features of contraction such as the radial compression of muscle fibers.

Muscle contraction, Actin

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