Position-dependent interactions between cysteine residues and the helix dipole
A protein model was developed for studying the interaction between cysteine residues and the helix dipole. Site-directed mutagenesis was used to introduce cysteine residues at the N-terminus of helix H in recombinant sperm whale myoglobin. Based on the difference in thiol pKa between folded proteins...
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ftpubmed:oai:pubmedcentral.nih.gov:2312398 2023-05-15T18:26:48+02:00 Position-dependent interactions between cysteine residues and the helix dipole Miranda, JJ L. 2003-01 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2312398 http://www.ncbi.nlm.nih.gov/pubmed/12493830 en eng Cold Spring Harbor Laboratory Press http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2312398 http://www.ncbi.nlm.nih.gov/pubmed/12493830 Copyright © Copyright 2003 The Protein Society Article Text 2003 ftpubmed 2013-09-01T18:45:15Z A protein model was developed for studying the interaction between cysteine residues and the helix dipole. Site-directed mutagenesis was used to introduce cysteine residues at the N-terminus of helix H in recombinant sperm whale myoglobin. Based on the difference in thiol pKa between folded proteins and an unfolded peptide, the energy of interaction between the thiolate and the helix dipole was determined. Thiolates at the N1 and N2 positions of the helix were stabilized by 0.3 kcal/mole and 0.7 kcal/mole, respectively. A thiolate at the Ncap position was stabilized by 2.8 kcal/mole, and may involve a hydrogen bond. In context with other studies, an experimentally observed helix dipole effect may be defined in terms of two distinct components. A charge-dipole component involves electrostatic interactions with peptide bond dipoles in the first two turns of the helix and affects residues at all positions of the terminus; a hydrogen bond component involves one or more backbone amide groups and is only possible at the capping position due to conformational restraints elsewhere. The nature and magnitude of the helix dipole effect is, therefore, position-dependent. Results from this model system were used to interpret cysteine reactivity in rodent hemoglobins and the thioredoxin family. Text Sperm whale PubMed Central (PMC) |
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Article Miranda, JJ L. Position-dependent interactions between cysteine residues and the helix dipole |
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description |
A protein model was developed for studying the interaction between cysteine residues and the helix dipole. Site-directed mutagenesis was used to introduce cysteine residues at the N-terminus of helix H in recombinant sperm whale myoglobin. Based on the difference in thiol pKa between folded proteins and an unfolded peptide, the energy of interaction between the thiolate and the helix dipole was determined. Thiolates at the N1 and N2 positions of the helix were stabilized by 0.3 kcal/mole and 0.7 kcal/mole, respectively. A thiolate at the Ncap position was stabilized by 2.8 kcal/mole, and may involve a hydrogen bond. In context with other studies, an experimentally observed helix dipole effect may be defined in terms of two distinct components. A charge-dipole component involves electrostatic interactions with peptide bond dipoles in the first two turns of the helix and affects residues at all positions of the terminus; a hydrogen bond component involves one or more backbone amide groups and is only possible at the capping position due to conformational restraints elsewhere. The nature and magnitude of the helix dipole effect is, therefore, position-dependent. Results from this model system were used to interpret cysteine reactivity in rodent hemoglobins and the thioredoxin family. |
format |
Text |
author |
Miranda, JJ L. |
author_facet |
Miranda, JJ L. |
author_sort |
Miranda, JJ L. |
title |
Position-dependent interactions between cysteine residues and the helix dipole |
title_short |
Position-dependent interactions between cysteine residues and the helix dipole |
title_full |
Position-dependent interactions between cysteine residues and the helix dipole |
title_fullStr |
Position-dependent interactions between cysteine residues and the helix dipole |
title_full_unstemmed |
Position-dependent interactions between cysteine residues and the helix dipole |
title_sort |
position-dependent interactions between cysteine residues and the helix dipole |
publisher |
Cold Spring Harbor Laboratory Press |
publishDate |
2003 |
url |
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2312398 http://www.ncbi.nlm.nih.gov/pubmed/12493830 |
genre |
Sperm whale |
genre_facet |
Sperm whale |
op_relation |
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2312398 http://www.ncbi.nlm.nih.gov/pubmed/12493830 |
op_rights |
Copyright © Copyright 2003 The Protein Society |
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