4E7T

The structure of T6 bovine insulin

Summary for 4E7T

• Entry DOI: 10.2210/pdb4e7t/pdb
• Related: 2A3G 4E7U 4E7V
• Descriptor: Insulin A chain, Insulin B chain, ZINC ION, ... (4 entities in total)
• Functional Keywords: zinc binding, hormone
• Biological source: Bos taurus (bovine,cow,domestic cattle,domestic cow); More
• Cellular location: Secreted: P01317 P01317
• Total number of polymer chains: 4
• Total formula weight: 11617.96

Authors

Harris, P.,Frankaer, C.G.,Knudsen, M.V. (deposition date: 2012-03-19, release date: 2012-04-04, Last modification date: 2024-11-06)

Primary citation

Frankar, C.G.,Knudsen, M.V.,Noren, K.,Nazarenko, E.,Stahl, K.,Harris, P.
The structures of T(6), T(3)R(3) and R(6) bovine insulin: combining X-ray diffraction and absorption spectroscopy.
Acta Crystallogr.,Sect.D, 68:1259-1271, 2012

PubMed Abstract: The crystal structures of three conformations, T(6), T(3)R(3) and R(6), of bovine insulin were solved at 1.40, 1.30 and 1.80 Å resolution, respectively. All conformations crystallized in space group R3. In contrast to the T(6) and T(3)R(3) structures, different conformations of the N-terminal B-chain residue PheB1 were observed in the R(6) 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 R(3) sites and an octahedral coordination in T(3) sites. The coordination distances were refined from XAS with a standard deviation of <0.01 Å. 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 T(3) sites in particular. Furthermore, XANES spectra for the zinc sites in T(6) and R(6) insulin were successfully calculated using finite difference methods and the bond distances and angles were optimized from a quantitative XANES analysis.

PubMed: 22993080
DOI: 10.1107/S090744491202625X

Experimental method

X-RAY DIFFRACTION (1.4 Å)