Single molecular functional assay of ferritin arrays

Abstract

In situ functional assay of each ferritin molecule in single-layer 2D arrays for horse spleen apoferritin and recombinant horse L- and human H-apoferritins was conducted by observing the iron-cores formed in the arrays by TEM. The study of the time-course, pH-dependence, and temperature-dependence of the function confirmed the iron-core formation to be due to the native function of apoferritins in array. Dark-field TEM imaging revealed that there was crystallinity in the cores in the array of recombinant human H-apoferritin. This iron-core formation was perfectly preserved in the array even after 3 months of storage at room temperature and low humidity. Moreover, about 50% of the function was found to remain in the array after it was exposed to 150 ° C in vacuum for 1 hr.