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Characterization of a new four‐chain coiled‐coil: Influence of chain length on stability
Author(s) -
Fairman Robert,
Chao HannGuang,
Mueller Luciano,
Lavoie Thomas B.,
Shen Liyang,
Novotny Jiri,
Matsueda Gary R.
Publication year - 1995
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1002/pro.5560040803
Subject(s) - cooperativity , coiled coil , chemistry , tetramer , sedimentation equilibrium , crystallography , monomer , size exclusion chromatography , peptide , protein folding , dissociation (chemistry) , side chain , ultracentrifuge , polymer , chromatography , organic chemistry , biochemistry , enzyme
Limited information is available on inherent stabilities of four‐chain coiled‐coils. We have developed a model system to study this folding motif using synthetic peptides derived from sequences contained in the tetramerization domain of Lac repressor. These peptides are tetrameric as judged by both gel filtration and sedimentation equilibrium and the tetramers are fully helical as determined by CD. The four‐chain coiled‐coils are well folded as judged by the cooperativity of thermal unfolding and by the extent of dispersion in aliphatic chemical shifts seen in NMR spectra. In addition, we measured the chain length dependence of this four‐chain coiled‐coil. To this end, we developed a general procedure for nonlinear curve fitting of denaturation data in oligomeric systems. The dissociation constants for bundles that contain α‐helical chains 21, 28, and 35 amino acids in length are 3.1 × 10 −12 , 6.7 × 10 −23 , and 1.0 × 10 −38 M 3 , respectively. This corresponds to tetramer stabilities (in terms of the peptide monomer concentration) of 180 μM, 51 nM, and 280 fM, respectively. Finally, we discuss the rules governing coiled‐coil formation in light of the work presented here.