| Autor: |
Roy, M, Brader, M L, Lee, R W, Kaarsholm, N C, Hansen, J F, Dunn, M F |
| Zdroj: |
Journal of Biological Chemistry; November 1989, Vol. 264 Issue: 32 p19081-19085, 5p |
| Abstrakt: |
The cobalt(II)-substituted human insulin hexamer has been shown to undergo the phenol-induced T6to R6structural transition in solution. The accompanying octahedral to tetrahedral change in ligand field geometry of the cobalt ions results in dramatic changes in the visible region of the electronic spectrum and thus represents a useful spectroscopic method for studying the T to R transition. Changes in the Co2+spectral envelope show that the aqua ligand associated with each tetrahedral Co2+ center can be replaced by SCN-, CN-, OCN-, N3-, Cl-, and NO2-. 19F NMR experiments show that the binding of m-trifluorocresol stabilizes the R6state of zinc insulin. The chemical shift and line broadening of the CF3 singlet, which occur due to binding, provide a useful probe of the T6 to R6transition. Due to the appearance of new resonances in the aromatic region, the 500 MHz 1H NMR spectrum of the phenol-induced R6 hexamer is readily distinguishable from that of the T6form. 1H NMR studies show that phenol induces the T6to R6transition, both in the (GlnB13)6(Zn2+)2hexamer and in the metal-free GlnB13 species; we conclude that metal binding is not a prerequisite for formation of the R state in this mutant. |
| Databáze: |
Supplemental Index |
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