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PDBsum entry 2nth
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References listed in PDB file
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Key reference
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Title
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Structural determinants of nitroxide motion in spin-Labeled proteins: tertiary contact and solvent-Inaccessible sites in helix g of t4 lysozyme.
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Authors
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Z.Guo,
D.Cascio,
K.Hideg,
T.KáláI,
W.L.Hubbell.
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Ref.
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Protein Sci, 2007,
16,
1069-1086.
[DOI no: ]
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PubMed id
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Abstract
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A nitroxide side chain (R1) has been substituted at single sites along a
helix-turn-helix motif in T4 lysozyme (residues 114-135). Together with
previously published data, the new sites reported complete a continuous scan
through the motif. Mutants with R1 at sites 115 and 118 were selected for
crystallographic analysis to identify the structural origins of the
corresponding two-component EPR spectra. At 115, R1 is shown to occupy two
rotamers in the room temperature crystal structure, one of which has not been
previously reported. The two components in the EPR spectrum apparently arise
from differential interactions of the two rotamers with the surrounding
structure, the most important of which is a hydrophobic interaction of the
nitroxide ring. Interestingly, the crystal structure at 100 K reveals a single
rotamer, emphasizing the possibility of rotamer selection in low-temperature
crystal structures. Residue 118 is at a solvent-inaccessible site in the protein
core, and the structure of 118R1, the first reported for the R1 side chain at a
buried site, reveals how the side chain is accommodated in an overpacked core.
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Figure 8.
Figure 8. The effect of dioxane and mutation of nearest-neighbor residues
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The above figure is
reprinted
by permission from the Protein Society:
Protein Sci
(2007,
16,
1069-1086)
copyright 2007.
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