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Figure 1.
Figure 1. NMR solution structure of the N-terminal domain
of DNA polymerase b. (a) An overlay of 25 superimposed
conformers (residues 11-80) showing several of the side-chains
important for hydrophobic packing, DNA binding and catalysis.
The structure is composed of four helices (15-28, 35-47, 56-61
and 68-78). The backbone of residues 11-55 are shown in magenta
while residues 56-80 are in green. Hydrophobic side-chains are
colored gold, hydrophilic brown, negatively charged red, and
positively charged blue. (b) A backbone trace of 25 superimposed
conformers of residues 10-80 demonstrating the results from the
15N relaxation measurements. The color code is as follows: blue,
residues fit with S2 only; gold, residues with slow
conformational exchange (R[ex]); red, residues with slow
internal motions (t[e]); green, residues fit with both R[ex] and
t[e]. (c) A ribbon representation for the minimized average
structures (residues 9-82) illustrating residues with
significant chemical shift changes upon addition of DNA. Colors
are from a consensus of chemical shift effects for four DNA
fragments; a 5mer ssDNA, a p(dT[8]) ssDNA, a 9mer ssDNA
containing a single U at the center, and a 12mer dsDNA fragment.
No significant changes in the surface for DNA binding occurs
between the four DNA fragments. Colors represent the degree of
chemical shift perturbations as follows: red > gold > green >
blue.
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