Physical Molecular Biology Section
University of Pittsburgh Laboratory of Physical Molecular Biology; Sanford Leuba, Ph.D.
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Simulated and Experimental SFM images of Native Chromatin Fibers.
All images are 250 x 250 nm in size.
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A. Computer-generated Image
of a Model Chromatin Fiber.
B. Simulated SFM Image
of the Model Chromatin Fiber in 'A'.
Experimental SFM Image of a
Glutaraldehyde-fixed Chromatin Fiber

Using the following constraints:
(1) the linker histones H1 and H5 help maintain the DNA entry/exit angle on the nucleosome; (2) the DNA linkers between nucleosomes are rigid and straight under the low ionic conditions used here; and (3) the DNA linker length varies within biochemically defined limits (constant linkers would generate a regular helical fiber of nucleosomes); we have been able to model at a first approximation the irregular, three-dimensional character of chromatin fibers.