Stereochemistry of residues in turning regions of helical proteins
- Creators
- Kozak, John J.
- Gray, Harry B.
Abstract
We have developed a geometrical approach to quantify differences in the stereochemistry of α-helical and turning regions in four iron proteins. Two spatial signatures are used to analyze residue coordinate data for each protein; and a third is employed to analyze amino-acid molecular volume data. The residue-by-residue analysis of the results, taken together with the finding that two major factors stabilize an α-helix (minimization of side-chain steric interference and intrachain H-bonding), lead to the conclusion that certain residues are preferentially selected for α-helix formation. In the sequential, de novo synthesis of a turning region, residues are preferentially selected such that the overall molecular volume profile (representing purely repulsive, excluded-volume effects) spans a small range Δ of values (Δ = 39.1 Å^3) relative to the total range that could be spanned (Δ = 167.7 Å^3). It follows that excluded-volume effects are of enormous importance for residues in helical regions as well as those in adjacent turning regions. Once steric effects are taken into account, down-range attractive interactions between residues come into play in the formation of α-helical regions. The geometry of α-helices can be accommodated by conformational changes in less-structured turning regions of a polypeptide, thereby producing a globally optimized (native) protein structure.
Additional Information
© 2019 Society for Biological Inorganic Chemistry (SBIC). Received: 26 June 2019; Accepted: 2 August 2019; First Online: 11 September 2019. Work at Caltech was supported by the National Institutes of Health (DK-019038 to HBG).Additional details
- Eprint ID
- 98578
- DOI
- 10.1007/s00775-019-01696-9
- Resolver ID
- CaltechAUTHORS:20190911-131606828
- DK-019038
- NIH
- Created
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2019-09-11Created from EPrint's datestamp field
- Updated
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2021-11-16Created from EPrint's last_modified field