Comparison of <i>apo</i>- and Zn²⁺-t-PhtD.

<p>(A) Weighted chemical shift difference determined for the amide resonances between the two forms (Δδ = [(Δδ¹H)²+(0.01 Δδ¹⁵N)²]^1/2). The insert shows a color-coded projection of the chemical shift differences onto the ribbon structure of Zn²⁺-t-PhtD. Residues for which no resonance could be identified in the ¹H,¹⁵N-HSQC spectrum of <i>apo</i>-t-PhtD are shown in orange and proline residues in white. Residues with significant chemical shift differences are identified by their residue numbers. (B) Ratio of transverse (<i>R</i>₂) and longitudinal (<i>R</i>₁) relaxation rates and (C) {¹H}¹⁵N-heteronuclear NOE for <i>apo</i>- (red squares) and Zn²⁺-t-PhtD (black triangles). Secondary structure elements identified in the structure of Zn²⁺-t-PhtD are indicated on the top of the figure and by grey shadows in each of the panels.