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PDBsum entry 5uxt
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De novo protein
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PDB id
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5uxt
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References listed in PDB file
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Key reference
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Title
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Enhancing a long-Range salt bridge with intermediate aromatic and nonpolar amino acids.
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Authors
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M.S.Smith,
W.M.Billings,
F.G.Whitby,
M.B.Miller,
J.L.Price.
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Ref.
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Org Biomol Chem, 2017,
15,
5882-5886.
[DOI no: ]
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PubMed id
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Abstract
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The interaction of a positively charged amino acid residue with a negatively
charged residue (i.e. a salt bridge) can contribute substantially to protein
conformational stability, especially when two ionic groups are in close
proximity. At longer distances, this stabilizing effect tends to drop off
precipitously. However, several lines of evidence suggest that salt-bridge
interaction could persist at longer distances if an aromatic amino acid residue
were positioned between the anion and cation. Here we explore this possibility
in the context of a peptide in which a Lys residue occupies the i + 8 position
relative to an i-position Glu on the solvent-exposed surface of a helix-bundle
homotrimer. Variable temperature circular dichroism (CD) experiments indicate
that an i + 4-position Trp enables a favorable long-range interaction between
Glu and the i + 8 Lys. A substantial portion of this effect relies on the
presence of a hydrogen-bond donor on the arene; however, non-polar arenes, a
cyclic hydrocarbon, and an acyclic Leu side-chain can also enhance the
long-range salt bridge, possibly by excluding water and ions from the space
between Glu and Lys.
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