 |
PDBsum entry 1lll
|
|
|
|
References listed in PDB file
|
 |
|
Key reference
|
|
|
Title
|
|
A test of proposed rules for helix capping: implications for protein design.
|
|
|
Authors
|
|
M.Sagermann,
L.G.Mårtensson,
W.A.Baase,
B.W.Matthews.
|
|
|
Ref.
|
|
Protein Sci, 2002,
11,
516-521.
[DOI no: ]
|
|
|
PubMed id
|
|
|
|
|
|
|
|
|
Abstract
|
|
|
alpha-helices within proteins are often terminated (capped) by distinctive
configurations of the polypeptide chain. Two common arrangements are the
Schellman motif and the alternative alpha(L) motif. Rose and coworkers developed
stereochemical rules to identify the locations of such motifs in proteins of
unknown structure based only on their amino acid sequences. To check the
effectiveness of these rules, they made specific predictions regarding the
structural and thermodynamic consequences of certain mutations in T4 lysozyme.
We have constructed these mutants and show here that they have neither the
structure nor the stability that was predicted. The results show the complexity
of the protein-folding problem. Comparison of known protein structures may show
that a characteristic sequence of amino acids (a sequence motif) corresponds to
a conserved structural motif. In any particular protein, however, changes in
other parts of the sequence may result in a different conformation. The
structure is determined by sequence as a whole, not by parts considered in
isolation.
|
|
|
|
|
|
Figure 1.
Fig. 1. (a) Schematic illustration of the hydrogen-bonding
interactions (red lines) in a Schellman motif. As noted by
Aurora et al. (1994) such motifs have a preference for glycine
at C` and an apolar residue at C". (b) Schematic illustration
showing the backbone hydrogen-bonding interactions (red lines)
in a typical  [L] capping
motif, as well as the sequence of the subject motif in T4
lysozyme (in blue). Such motifs commonly have a glycine at the C
 position and a
polar residue at C". (In her original article, Schellman [1980]
proposed the name [L] for the
conformation shown in panel a. Aurora et al. [1994] renamed this
the Schellman motif and used [L] to
designate the conformation shown in panel b.)
|
|
|
|
|
|
The above figure is
reprinted
by permission from the Protein Society:
Protein Sci
(2002,
11,
516-521)
copyright 2002.
|
|
|
|
|
|
|
