FIGURE 4.

Location and orientation of DASPMI in the mitochondrial inner membrane. DASPMI preferentially locates its positively charged methyl pyridinium ring in the aqueous interface facing the outer mitochondrial membrane, and its hydrophobic moiety along the hydrocarbon chain. As for orientation, it aligns itself along the local electric field for a maximum electrochromic response. Under high-membrane-potential conditions, the delocalization of π-electrons leads to a less polar structure, imposing steric constraints on the single bonds neighboring the olefinic double bond.