Simultaneous Counting of Molecules in the Halo and Dense-Core of Nanovesicles by Regulating Dynamics of Vesicle Opening

We report the discovery that in the presence of chaotropic anions (SCN-) the opening of nanometer biological vesicles at an electrified interface often becomes a two-step process (around 30 % doublet peaks). We have then used this to independently count molecules in each subvesicular compartment, the halo and protein dense-core, and the fraction of catecholamine binding to the dense-core is 68 %. Moreover, we differentiated two distinct populations of large dense-core vesicles (LDCVs) and quantified their content, which might correspond to immature (43 %) and mature (30 %) LDCVs, to reveal differences in their biogenesis. We speculate this is caused by an increase in the electrostatic attraction between protonated catecholamine and the negatively charged dense-core following adsorption of SCN-.

Automated summary

In the presence of chaotropic anions, the opening of nanometer biological vesicles becomes a two-step process, allowing for independent counting of molecules in each subvesicular compartment. The study revealed a 68% catecholamine binding to the dense-core and differentiated two populations of large dense-core vesicles, with differences in biogenesis speculated to be caused by an increase in electrostatic attraction.