Attachment and Detachment Processes of Individual Lysozyme Molecules on a Surface of a Monoclinic Lysozyme Crystal Studied by Fluorescent Single-Molecule Visualization

摘要

On a {101-bar} face of a monoclinic crystal of hen egg-white lysozyme (HEWL), we visualized the attachment and detachment processes of individual fluorescent-labeled HEWL (F-HEWL) molecules by a fluorescent single-molecule visualization technique. We measured the changes in number density of F-HEWL molecules, whose positions were not changed for longer than a certain residence time, as a function of an adsorption time. We first confirmed that under an equilibrium condition, there was an "induction period" (~120 min) of the attachment/detachment processes, during which period the number density remained constant. After the induction period, the number density increased linearly with the adsorption time, as it was recently found on a tetragonal HEWL crystal [Dai, G. L. Cryst. Growth Des 2011, 11(1), 88-92]. In addition, we performed similar measurements under a supersaturated condition. Then we found that supersaturation significantly enhanced the attachment process after the induction time. The attachment/detachment processes finally reached a steady state, in which the attachment rate was higher than the detachment one. Moreover, we also found that in a rare case, an F-HEWL molecule adsorbed on a step laterally moved following the advancement of a growing step.