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Making Proteins See the Light
Although nature provides remarkable
examples of the materials properties
of proteins (e.g., the strength and
elasticity of spider silk), the technological
development of protein-based materials
has been frustrated by the difficulty
of processing proteins and protein-like
macromolecules into useful fibers,
films and surface coatings. Researchers
in the Center for the Science and
Engineering of Materials at the California
Institute of Technology have recently
taken an important step toward solving
this problem, by preparing proteins
that can be processed by methods that
are already in widespread use in the
electronics industry. The approach
uses bacterial cells to express artificial
proteins that contain amino acid building
blocks that are different from those
that appear in natural proteins. In
particular, amino acids that are sensitive
to light can be used to link together
individual protein molecules into
tough networks that resist dissolution
in common solvents. Such "photoresists"
form the basis of manufacture of computer
chips, and methods for processing
of materials based on photoresist
technology have become highly sophisticated.
The figure below shows a pattern developed
in an artificial protein prepared
at Caltech.
The pattern was made by exposing selected
regions of a protein film to a light
source, while keeping other regions
protected from exposure. The film
was then treated with a solvent that
removes the unexposed protein while
leaving the exposed areas intact.
The features in the figure are approximately
10 microns (10 millionths of a meter)
across - about the size of a single
human cell. Current research addresses
the use of Caltech's photosensitive
proteins in biotechnology and health
care.
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