Fig. 2: Potassium ion binding site.
From: Comprehensive profiling of the catalytic conformations of human Guanylate kinase
a, b ITC analysis of GMPK binding to GMP in buffers containing 150 mM NaCl (blue curve) and 150 mM KCl (magenta curve), respectively. The displayed values represent the Kd and errors from triplicate experiments. c Kinetic parameters (KM, Ki, kcat and kcat/KM) for GMP obtained under various potassium and sodium ion conditions. d Cartoon representation of the GMPK-GMP-K+ complex, with a detailed view of the potassium ion binding site. Potassium ion is depicted as purple spheres, water molecules as red spheres, and the residues S37, D101, and GMP are shown in stick representation. The mFo-DFc omit map density (black mesh) for the Potassium ion and water molecules is shown at a contour level of 10σ. Dashed lines indicate interatomic distances. e Structural superposition of GMPK-GMP (white) and GMPK-GMP-K+ (aquamarine). Water molecules near the potassium binding site are shown as spheres. D101 and GMP are shown as sticks.
