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rdf:type |
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lifeskim:mentions |
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pubmed:issue |
5
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pubmed:dateCreated |
2010-2-17
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pubmed:abstractText |
Apomyoglobin folds by a sequential mechanism in which the A, G, and H helix regions undergo rapid collapse to form a compact intermediate onto which the central portion of the B helix subsequently docks. To investigate the factors that frustrate folding, we have made mutations in the N-terminus of the B helix to stabilize helical structure (in the mutant G23A/G25A) and to promote native-like hydrophobic packing interactions with helix G (in the mutant H24L/H119F). The kinetic and equilibrium intermediates of G23A/G25A and H24L/H119F were studied by hydrogen exchange pulse labeling and interrupted hydrogen/deuterium exchange combined with NMR. For both mutants, stabilization of helical structure in the N-terminal region of the B helix is confirmed by increased exchange protection in the equilibrium molten globule states near pH 4. Increased protection is also observed in the GH turn region in the G23A/G25A mutant, suggesting that stabilization of the B helix facilitates native-like interactions with the C-terminal region of helix G. These interactions are further enhanced in H24L/H119F. The kinetic burst phase intermediates of both mutants show increased protection, relative to wild-type protein, of amides in the N-terminus of the B helix and in part of the E helix. Stabilization of the E helix in the intermediate is attributed to direct interactions between E helix residues and the newly stabilized N-terminus of helix B. Stabilization of native packing between the B and G helices in H24L/H119F also favors formation of native-like interactions in the GH turn and between the G and H helices in the ensemble of burst phase intermediates. We conclude that instability at the N-terminus of the B helix of apomyoglobin contributes to the energetic frustration of folding by preventing docking and stabilization of the E helix.
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pubmed:grant |
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pubmed:commentsCorrections |
http://linkedlifedata.com/resource/pubmed/commentcorrection/20043917-10210182,
http://linkedlifedata.com/resource/pubmed/commentcorrection/20043917-10715109,
http://linkedlifedata.com/resource/pubmed/commentcorrection/20043917-10985768,
http://linkedlifedata.com/resource/pubmed/commentcorrection/20043917-11353859,
http://linkedlifedata.com/resource/pubmed/commentcorrection/20043917-12225742,
http://linkedlifedata.com/resource/pubmed/commentcorrection/20043917-14607120,
http://linkedlifedata.com/resource/pubmed/commentcorrection/20043917-14711991,
http://linkedlifedata.com/resource/pubmed/commentcorrection/20043917-15769860,
http://linkedlifedata.com/resource/pubmed/commentcorrection/20043917-16300787,
http://linkedlifedata.com/resource/pubmed/commentcorrection/20043917-18227434,
http://linkedlifedata.com/resource/pubmed/commentcorrection/20043917-18779573,
http://linkedlifedata.com/resource/pubmed/commentcorrection/20043917-2218495,
http://linkedlifedata.com/resource/pubmed/commentcorrection/20043917-3820301,
http://linkedlifedata.com/resource/pubmed/commentcorrection/20043917-7666424,
http://linkedlifedata.com/resource/pubmed/commentcorrection/20043917-8158639,
http://linkedlifedata.com/resource/pubmed/commentcorrection/20043917-8234246,
http://linkedlifedata.com/resource/pubmed/commentcorrection/20043917-8235610,
http://linkedlifedata.com/resource/pubmed/commentcorrection/20043917-8520219,
http://linkedlifedata.com/resource/pubmed/commentcorrection/20043917-8520220,
http://linkedlifedata.com/resource/pubmed/commentcorrection/20043917-8563639,
http://linkedlifedata.com/resource/pubmed/commentcorrection/20043917-9512718,
http://linkedlifedata.com/resource/pubmed/commentcorrection/20043917-9521748
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pubmed:language |
eng
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pubmed:journal |
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pubmed:citationSubset |
IM
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pubmed:chemical |
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pubmed:status |
MEDLINE
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pubmed:month |
Mar
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pubmed:issn |
1089-8638
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pubmed:author |
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pubmed:copyrightInfo |
Copyright (c) 2009 Elsevier Ltd. All rights reserved.
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pubmed:issnType |
Electronic
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pubmed:day |
12
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pubmed:volume |
396
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
1319-28
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pubmed:dateRevised |
2011-7-26
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pubmed:meshHeading |
pubmed-meshheading:20043917-Amino Acid Substitution,
pubmed-meshheading:20043917-Animals,
pubmed-meshheading:20043917-Apoproteins,
pubmed-meshheading:20043917-Hydrogen-Ion Concentration,
pubmed-meshheading:20043917-Kinetics,
pubmed-meshheading:20043917-Models, Molecular,
pubmed-meshheading:20043917-Mutagenesis, Site-Directed,
pubmed-meshheading:20043917-Myoglobin,
pubmed-meshheading:20043917-Nuclear Magnetic Resonance, Biomolecular,
pubmed-meshheading:20043917-Protein Folding,
pubmed-meshheading:20043917-Protein Stability,
pubmed-meshheading:20043917-Protein Structure, Secondary,
pubmed-meshheading:20043917-Protons,
pubmed-meshheading:20043917-Recombinant Proteins,
pubmed-meshheading:20043917-Sperm Whale,
pubmed-meshheading:20043917-Thermodynamics
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pubmed:year |
2010
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pubmed:articleTitle |
Energetic frustration of apomyoglobin folding: role of the B helix.
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pubmed:affiliation |
Department of Molecular Biology and Skaggs Institute of Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
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pubmed:publicationType |
Journal Article,
Research Support, N.I.H., Extramural
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