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Science Forum Index » Bio Evolution Forum » Article: Nature Could Have Used Different Protein Building B
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| Robert Karl Stonjek |
 Posted: Tue Feb 06, 2007 8:51 am |
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Nature Could Have Used Different Protein Building Blocks, Chemists Show
Science Daily - Chemists at Yale have done what Mother Nature chose not
to -- make a protein-like molecule out of non-natural building blocks,
according to a report featured early online in the Journal of the American
Chemical Society.
Nature uses alpha-amino acid building blocks to assemble the proteins that
make life as we know it possible. Chemists at Yale now report evidence that
nature could have used a different building block -- beta-amino acids -- and
show that peptides assembled from beta-amino acids can fold into structures
much like natural protein.
"The x-ray structure featured in the report shows a molecule that shares
many of the structural characteristics of natural proteins," said principal
author Alanna Schepartz, the Milton Harris '29 Ph.D. Professor of Chemistry
at Yale and a Howard Hughes Medical Institute Professor. "Related studies
show that the physical properties of the molecule are also remarkably
similar to natural proteins. In other words, the beta-peptide assembly looks
and acts a lot like a real protein."
The ability to mimic natural proteins makes beta-peptides powerful new tools
for basic research and drug discovery. Like a taped recording, their
greatest value may be in their difference from a live performance.
"Since beta-peptides are not processed in the cell like natural peptides or
proteins, it may be possible in the future to design beta-peptides that
perform better or in more locations than current protein drugs," said
Schepartz. "They also may have unique properties as biomaterials."
Natural proteins are composed of linear chains of alpha-amino acids.
Beta-peptides are composed of beta-amino acids, which have an extra carbon
in their backbone. Like alpha-amino acids, beta-amino acids are generated
under simulated pre-biotic conditions, are isolated from meteorites, and are
byproducts of metabolism, but they are not genetically encoded like natural
proteins, nor are they built into chains by cells.
Since the early 1990's, scientists have been able to assemble beta-peptides
into isolated helices. Until now, however, creating a structure that mimics
the larger size and complex folded architecture of a natural protein had
been an elusive goal. Schepartz's team solved the dilemma by designing a
molecule that could form a bundle using characteristics found in natural
proteins -- a greasy interior that repels water and a water-friendly
exterior. This paper, which provides the first high-resolution picture of
such a structure, shows a bundle of eight beta-peptides.
"The structure we see is intriguing, as it suggests that natural proteins
could have been composed of beta-amino acids, but were not chosen to do so,"
said Schepartz.
Co-authors on the paper are post-doctoral fellows Douglas S. Daniels and E.
James Petersson, and graduate student Jade X. Qiu. The research was
supported by the National Institutes of Health, the National Foundation for
Cancer Research and the Yale Center for Structural Biology.
Citation: J. American Chemical Society, ASAP Article DOI:10.1021/ja068678n
(January 19, 2007)
Source: Yale University
http://www.sciencedaily.com/releases/2007/02/070205231608.htm
Posted by
Robert Karl Stonjek |
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