Figure 5. Structure of VcCheY4 in free and sulphated states.

(a) stereo view of the superposition of VcCheY4^free (yellow) and VcCheY4^sulf (orange) on activated VcCheY3-BeF₃ ⁻ (green) showing the location and the interactions of the sulfate ion in VcCheY4^sulf, relative movement of T82, hydrogen bond between K89 and T82 in VcCheY4^sulf and the interactions of the metal ion with the neighbouring residues; (b) B′ plot of VcCheY4^free (black) and VcCheY4^sulf (orange) showing reduction of flexibility of the β4α4 loop (*) in VcCheY4^sulf; (c) superposition of VcCheY4^free (yellow) on VcCheY4^sulf (orange) showing the conformational difference at the β4α4 loop and packing of W101 in its exclusive ‘in’ position.