Imaging the ordered arrays of water-soluble protein ferritin with the atomic force microscope

Satomi Ohnishi, Masahiko Hara, Taiji Furuno, Hiroyuki Sasabe

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Individual water-soluble molecules of the protein ferritin have been imaged on a silicon surface in pure water at room temperature with the atomic force microscope (AFM). The ferritin molecules formed an ordered monolayer by binding to a charged polypeptide monolayer of poly-1-benzyl-L-histidine (PBLH) spread at the air-water interface. The film, fully wetted with water, was horizontally transferred onto an alkylated silicon wafer for AFM imagings. The hexagonal arrangement of ferritin molecules was imaged with high reproducibility on the whole surface of the film, since the forces between cantilever and the sample could be kept sufficiently smaller than 10-10 N, mainly due to a “self-screening effect” of the surface charges of the ferritin-PBLH layer. This is the first observation of two-dimensional ordered arrays of water-soluble protein molecules directly confirmed by AFM with molecular resolution.

Original languageEnglish
Pages (from-to)1425-1431
Number of pages7
JournalBiophysical Journal
Issue number5
Publication statusPublished - 1992 Jan 1


ASJC Scopus subject areas

  • Biophysics

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