Structural View of Biology
Biotechnology and Nanotechnology
Scientists are looking to nature for inspiration, and harnessing biological machinery for use in science and technology. Cells have evolved effective methods for performing a bewildering variety of nanoscale tasks. Many of these molecular machines may be used directly, by simply purifying the molecule and using it in the laboratory. Careful study of these molecular machines is also revealing the underlying nanoscale principles of their action, allowing researchers to create new molecular machines with novel functions.
Building on Nature
Researchers are using biomolecules as the starting point for design of nanotechnology. Existing biomolecules are being engineered for new functions, and entirely new biomolecules are being designed for completely new uses.
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Evolution is a great tinkerer: once a successful plan is found, it is used again and again, often with many changes and improvements. This is easily seen in the living things around us. Most mammals have four limbs, which have evolved into all manner of arms and legs, and even into flippers and wings. Most plants are covered with leaves, which range from spiny needles to huge jungle fronds. Looking at protein sequences and structures, we see the same diversity generated through variation.
Discussed Structuresconcanavalin Apeanut lectincircularly-permuted glucanasecircularly-permuted glucanasecircularly-permuted glucanase
DNA is a perfect raw material for constructing nanoscale structures. Since base-pairing has been selected by evolution to be highly specific, it is easy to design sequences that will link up with their proper mates. In this way, we can treat small pieces of DNA like Tinkertoys, designing individual components and then allowing them to assemble when we put them together. In addition, the chemistry of DNA synthesis has been completely automated, so custom pieces of DNA can be easily constructed, or even ordered from commercial biotech companies. This puts DNA nanotechnology in the hands of any modest laboratory, and many laboratories have taken advantage of this, creating nanoscale scaffolds, tweezers, polyhedra, computers, and even tiny illustrations composed entirely of DNA.
Discussed Structuresdesigned DNA crystalDNA with sticky ends
Scientists are great tinkerers, and surprisingly, proteins can often be used like tinkertoys. The proteins found in cells have evolved to have a stable, folded structures. Scientists are now building on these stable proteins and making changes to engineer new functions. These functions include designing new enzymes, designing proteins with improved medicinal properties, and designing large complexes with a desired shape and size.
Discussed StructuresDesigned Protein CageDesigned Protein CageDesigned Protein Cage
As we learn more and more about proteins and how they work, we naturally have the desire to use this knowledge and do some tinkering of our own. Since the early 1980's, scientists have been using the ever-expanding understanding of protein structure and function to redesign existing proteins, and more recently, to design entirely new proteins.
The green fluorescent protein, shown here from PDB entry 1gfl, is found in a jellyfish that lives in the cold waters of the north Pacific. The jellyfish contains a bioluminescent protein-- aequorin--that emits blue light. The green fluorescent protein converts this light to green light, which is what we actually see when the jellyfish lights up. Solutions of purified GFP look yellow under typical room lights, but when taken outdoors in sunlight, they glow with a bright green color. The protein absorbs ultraviolet light from the sunlight, and then emits it as lower-energy green light.
Discussed Structuresgreen fluorescent proteinengineered fluorescent protein
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