Adsorption to silica nanoparticles of human carbonic anhydrase II and truncated forms induce a molten-globule-like structure

FEBS Lett. 1997 Jan 27;402(1):67-72. doi: 10.1016/s0014-5793(96)01431-7.


Human carbonic anhydrase II pseudo-wild type (HCAIIpwt) and two truncated variants were adsorbed to approximately 9 nm silica nanoparticles. Ellipsometry was used as an indirect measure of protein adsorption. The structural changes of adsorbed proteins were investigated with the use of circular dichroism (CD), intrinsic fluorescence, ANS binding ability and inhibitor binding capacity. It was found that the variants that were truncated at positions 5 and 17 in the N-terminal end attain a molten-globule-like state after interaction with the silica nanoparticles. In contrast, the more stable HCAIIpwt retained most of its native structure after 24 h adsorption to silica nanoparticles. The result suggests that surface induced unfolding may give rise to intermediates similar to those for unfolding induced by, for example GuHCl. Thus, the intermediate observed has some features of the molten globule.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adsorption
  • Anilino Naphthalenesulfonates
  • Binding Sites
  • Carbonic Anhydrases / chemistry*
  • Carbonic Anhydrases / metabolism
  • Circular Dichroism
  • Dansyl Compounds / metabolism
  • Fluorescent Dyes / metabolism
  • Humans
  • Models, Molecular
  • Protein Conformation*
  • Protein Denaturation
  • Protein Folding
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • Silicon Dioxide
  • Spectrometry, Fluorescence


  • Anilino Naphthalenesulfonates
  • Dansyl Compounds
  • Fluorescent Dyes
  • 5-dimethylaminonaphthalene-1-sulfonamide
  • 1-anilino-8-naphthalenesulfonate
  • Silicon Dioxide
  • Carbonic Anhydrases