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![[Figure 6]](dw5156fig6mag.jpg)
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Figure 6
The three stages of refolding of the N-terminal region of muscle FBPase during the T-to-R transition. (a) In the T state in complex with AMP (ball-and-stick model) there is a long helix α1 (residues 13–23) at the N-terminus, near the AMP molecule, shown in an Fo − Fc OMIT electron-density map (grey mesh) contoured at the 4σ level. (b) In the T state, but without AMP, the segment Glu19–Thr31 is characterized by poor electron density (dashed loop omitted from the model) and there is only a short α-helical segment at the N-terminus. (c) In the R state the segment Glu19–Thr30 is characterized by poor electron density (dashed loop omitted from the model) and in the middle of the unfolded segment Thr8–Glu19 there is a new β-sheet (βα1) formed by residues Leu11–Arg15. The key N-terminal oligopeptides that change conformation on the T-to-R transition are shown in full atomic representation on the background of transparent secondary-structure elements in annealed Fo − Fc OMIT maps in (d), (e) and (f), corresponding to (a), (b) and (c), respectively. The fragments shown on the right and the corresponding map contour levels are Thr8–Lys25 and 4.0σ in (d), Leu11–Glu19 and 3.6σ in (e) and Thr8–Glu19 and 4.0σ in (f), respectively. |
![[Figure 6]](dw5156fig6.jpg)
 | STRUCTURAL BIOLOGY |
ISSN: 2059-7983
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