Making light work with optical tweezers

Article Abstract:

Optical tweezers or traps based on focused beams of infrared laser light are of great potential usefulness for the noninvasive control of microscopic objects. These revolutionary devices rely on the laser's radiation pressure to generate microscopic movement. This pressure is obtained by passing the laser light through an objective lens and then giving the light rays a horizontal momentum by focusing them through a refractile ball. The resulting three-dimensional light gradient can then move small objects. Adaptability is among the qualities that make optical tweezers superior to existing methods.

Methods, Usage, Lasers, Microscope and microscopy, Microscopes, Microscopy

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Real engines of creation

Article Abstract:

The atomic structure of the F(sub 1)-adenosine triphosphatase (ATPase) responsible for most of the cell's ATP synthesis suggested a possible mechanism of action. This rotary action has been confirmed by directly observing single F(sub 1)-ATPase molecules attached to a fluorescent actin filament. When synthesizing ATP, the stoichiometry of the reaction implies that the enzyme can rotate 40 times/second. However, the drag of the attached actin filament slowed this to at most 4 r.p.s., which suggests that the motor can produce torques of as much as 40 pN nm(supra 1) under load.

Analysis, Cells, Molecular dynamics, Cell migration, Adenosine triphosphatase, Cell research, Cytological research

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One small step for myosin...

Article Abstract:

The myosin subfragment one (S1) and a heavy meromyosin (HMM) produce similar steps and forces at the macromolecule level. S1 is a single-headed domain but HMM is a two-headed proteolytic fragment with a functional end of myosin. With the binding of actin to myosin, the motor associates with the filament and generates a step. The single heads function in vitro at high densities, but the movement is slow. The linkage of the single-headed constructs to the substrate lead to inactivated or sterically blocked heads.

Motor neurons, Myosin

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