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The structures of T6, T3R3 and R6 bovine insulin: combining X-ray diffraction and absorption spectroscopy

Frankaer, Christian Grundahl; Knudsen, Marianne Vad; Norén, Katarina LU ; Nazarenko, Elena; Stahl, Kenny and Harris, Pernille (2012) In Acta Crystallographica. Section D: Biological Crystallography 68. p.1259-1271
Abstract
The crystal structures of three conformations, T6, T3R3 and R6, of bovine insulin were solved at 1.40, 1.30 and 1.80 angstrom resolution, respectively. All conformations crystallized in space group R3. In contrast to the T6 and T3R3 structures, different conformations of the N-terminal B-chain residue PheB1 were observed in the R6 insulin structure, resulting in an eightfold doubling of the unit-cell volume upon cooling. The zinc coordination in each conformation was studied by X-ray absorption spectroscopy (XAS), including both EXAFS and XANES. Zinc adopts a tetrahedral coordination in all R3 sites and an octahedral coordination in T3 sites. The coordination distances were refined from XAS with a standard deviation of <0.01 angstrom.... (More)
The crystal structures of three conformations, T6, T3R3 and R6, of bovine insulin were solved at 1.40, 1.30 and 1.80 angstrom resolution, respectively. All conformations crystallized in space group R3. In contrast to the T6 and T3R3 structures, different conformations of the N-terminal B-chain residue PheB1 were observed in the R6 insulin structure, resulting in an eightfold doubling of the unit-cell volume upon cooling. The zinc coordination in each conformation was studied by X-ray absorption spectroscopy (XAS), including both EXAFS and XANES. Zinc adopts a tetrahedral coordination in all R3 sites and an octahedral coordination in T3 sites. The coordination distances were refined from XAS with a standard deviation of <0.01 angstrom. In contrast to the distances determined from the medium-resolution crystal structures, the XAS results were in good agreement with similar coordination geometries found in small molecules, as well as in other high-resolution insulin structures. As the radiation dose for XRD experiments is two orders of magnitude higher compared with that of XAS experiments, the single crystals were exposed to a higher degree of radiation damage that affected the zinc coordination in the T3 sites in particular. Furthermore, XANES spectra for the zinc sites in T6 and R6 insulin were successfully calculated using finite difference methods and the bond distances and angles were optimized from a quantitative XANES analysis. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
bovine insulin, insulin conformations, X-ray absorption spectroscopy, EXAFS, XANES
in
Acta Crystallographica. Section D: Biological Crystallography
volume
68
pages
1259 - 1271
publisher
International Union of Crystallography
external identifiers
  • wos:000308936200001
  • scopus:84866703986
ISSN
1399-0047
DOI
10.1107/S090744491202625X
language
English
LU publication?
yes
id
8b3a45e5-cb93-4c05-803b-6852b9d74b70 (old id 3189679)
date added to LUP
2012-12-04 14:39:54
date last changed
2017-06-25 03:51:34
@article{8b3a45e5-cb93-4c05-803b-6852b9d74b70,
  abstract     = {The crystal structures of three conformations, T6, T3R3 and R6, of bovine insulin were solved at 1.40, 1.30 and 1.80 angstrom resolution, respectively. All conformations crystallized in space group R3. In contrast to the T6 and T3R3 structures, different conformations of the N-terminal B-chain residue PheB1 were observed in the R6 insulin structure, resulting in an eightfold doubling of the unit-cell volume upon cooling. The zinc coordination in each conformation was studied by X-ray absorption spectroscopy (XAS), including both EXAFS and XANES. Zinc adopts a tetrahedral coordination in all R3 sites and an octahedral coordination in T3 sites. The coordination distances were refined from XAS with a standard deviation of &lt;0.01 angstrom. In contrast to the distances determined from the medium-resolution crystal structures, the XAS results were in good agreement with similar coordination geometries found in small molecules, as well as in other high-resolution insulin structures. As the radiation dose for XRD experiments is two orders of magnitude higher compared with that of XAS experiments, the single crystals were exposed to a higher degree of radiation damage that affected the zinc coordination in the T3 sites in particular. Furthermore, XANES spectra for the zinc sites in T6 and R6 insulin were successfully calculated using finite difference methods and the bond distances and angles were optimized from a quantitative XANES analysis.},
  author       = {Frankaer, Christian Grundahl and Knudsen, Marianne Vad and Norén, Katarina and Nazarenko, Elena and Stahl, Kenny and Harris, Pernille},
  issn         = {1399-0047},
  keyword      = {bovine insulin,insulin conformations,X-ray absorption spectroscopy,EXAFS,XANES},
  language     = {eng},
  pages        = {1259--1271},
  publisher    = {International Union of Crystallography},
  series       = {Acta Crystallographica. Section D: Biological Crystallography},
  title        = {The structures of T6, T3R3 and R6 bovine insulin: combining X-ray diffraction and absorption spectroscopy},
  url          = {http://dx.doi.org/10.1107/S090744491202625X},
  volume       = {68},
  year         = {2012},
}