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| {{STRUCTURE_1ce9| PDB=1ce9 | SCENE= }} | | {{STRUCTURE_1ce9| PDB=1ce9 | SCENE= }} |
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| '''HELIX CAPPING IN THE GCN4 LEUCINE ZIPPER'''
| | ===HELIX CAPPING IN THE GCN4 LEUCINE ZIPPER=== |
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| ==Overview==
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| Capping interactions associated with specific sequences at or near the ends of alpha-helices are important determinants of the stability of protein secondary and tertiary structure. We investigate here the role of the helix-capping motif Ser-X-X-Glu, a sequence that occurs frequently at the N termini of alpha helices in proteins, on the conformation and stability of the GCN4 leucine zipper. The 1.8 A resolution crystal structure of the capped molecule reveals distinct conformations, packing geometries and hydrogen-bonding networks at the amino terminus of the two helices in the leucine zipper dimer. The free energy of helix stabilization associated with the hydrogen-bonding and hydrophobic interactions in this capping structure is -1.2 kcal/mol, evaluated from thermal unfolding experiments. A single cap thus contributes appreciably to stabilizing the terminated helix and thereby the native state. These results suggest that helix capping plays a further role in protein folding, providing a sensitive connector linking alpha-helix formation to the developing tertiary structure of a protein.
| | The line below this paragraph, {{ABSTRACT_PUBMED_10329176}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 10329176 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_10329176}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Protein folding]] | | [[Category: Protein folding]] |
| [[Category: Thermal stability]] | | [[Category: Thermal stability]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 12:37:58 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jun 30 20:37:32 2008'' |
