Figure 2

Structural view of the four selected MTX-IK _Ca channel-binding modes along with the comparison of the calculated and experimental effects. Each row of figures is as follows: (top) the different spatial orientations of MTX in its complex with the IK_Ca channel from four main binding modes; (middle) the representative positions of the Lys23 and Tyr32 side chains in four main binding modes distinguished by different colors; (bottom) the comparison of the calculated and experimental effects for the five alanine mutations of MTX on the binding affinity toward the IK_Ca channel after 500-ps unrestrained MDS. The calculated results are normalized values of ΔΔG_binding, whereas the experimental results are obtained as k _b T ln [IC₅₀(mutant)/IC₅₀(wt)].