Kinetic scheme to account for the charge loss in the mutant R232H. At negative potentials, the VSD dwells in the resting state (R_P), where the residue R232H remains protonated (R232H-H⁺). Pulsing to more a positive potential promotes the transition to the active state (A_P). From A_P, the residue R232H can transit to a deprotonated active state (A_D), becoming uncharged (R232H). If the membrane potential is returned to negative values, the fraction of VSD in the A_P state can return to the R_P state, whereas those in the A_D state will return to deprotonated resting state (R_D). If the membrane potential remains positive, a secondary transition will take place, leading the VSD to a locked active state (A_T). This state is stable and transitions from it are infrequent, making this state a pseudo-absorbing state. Upon returning to negative potentials, a transition to a hypothetical locked resting state (R_T) is expected. It assumed that transitions between these active states are voltage independent and so are those between resting states.