Size-dependent impact of CNTs on dynamic properties of calmodulin

Jian Gao, Liming Wang, Seung Gu Kang, Lina Zhao, Mingjuan Ji, Chunying Chen, Yuliang Zhao, Ruhong Zhou, Jingyuan Li

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


There are growing concerns about the biosafety of nanomaterials such as carbon nanotubes (CNTs) as their applications become more widespread. We report here a theoretical and experimental study of the binding of various sizes of CNTs [CNT (4,4), (5,5), (6,6) and (7,7)] to calmodulin (CaM) protein and, in particular, their impact on the Ca2+-dependent dynamic properties of CaM. Our simulations show that all the CNTs can plug into the hydrophobic binding pocket of Ca2+-bound CaM with binding affinities comparable with the native substrate M13 peptide. Even though CNT (4,4) shows a similar behavior to the M13 peptide in its dissociation from Ca2+-free CaM, wider CNTs still bind firmly to CaM, indicating a potential failure of Ca2+ regulation. Such a size-dependent impact of CNTs on the dynamic properties of CaM is a result of the excessively strong hydrophobic interactions between the wider CNTs and CaM. These simulation results were confirmed by circular dichroism spectroscopy, which showed that the secondary structures of CaM become insensitive to Ca2+ concentrations after the addition of CNTs. Our findings indicate that the cytotoxicity of nanoparticles to proteins arises not only from the inhibition of static protein structures (binding pockets), but also from impacts on their dynamic properties.

Original languageEnglish (US)
Pages (from-to)12828-12837
Number of pages10
Issue number21
StatePublished - Nov 7 2014

ASJC Scopus subject areas

  • Materials Science(all)


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