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<DIV>From <A
href="http://www.futurepundit.com/archives/001837.html">FuturePundit</A>: Steven
M. Block, a professor of biological sciences and of applied physics at Stanford
University, and his team have developed <A
href="http://news-service.stanford.edu/news/2003/december3/rna-123.html">two-dimensional
optical force clamps that can monitor the action of a single RNA polymerase
(RNAP) enzyme</A>. <BR>In a new study in the journal Nature, Block and his
colleagues present strong evidence to support this proofreading hypothesis.
Their results -- based on actual observations of individual molecules of RNAP --
are posted on Nature's website: http://www.nature.com. In another set of
experiments published in the Nov. 14 issue of Cell magazine, the researchers
discovered that RNAP makes thousands of brief pauses as it pries open and copies
the DNA double helix. <BR>"Together these two papers push the study of single
proteins to new limits," Block said. "We've been able to achieve a resolution of
three angstroms -- the width of three hydrogen atoms -- in our measurements of
the progress of this enzyme along DNA. In so doing, we've been able to visualize
a backtracking motion of just five bases that accompanies RNAP error-correction
or proofreading." <BR>This is an example of why the rate of advance in
biological science is not constant. The development of instrumentation that can
study components of biological systems down on the scale at which they operate
will allow these systems to be figured out orders of magnitude more quickly. The
biggest reason we still know only a small fraction of what there is to
understand about cells and diseases is that we can't watch what happens down at
the level at which events actually take place. Continued advances in the ability
to build smaller devices and smaller sensors will make observable that which it
has previously never been possible to observe.</DIV></BODY></HTML>