A high-throughput assay shows that DNase-I binds actin monomers and polymers with similar affinity

Anal Biochem. 2007 May 15;364(2):159-64. doi: 10.1016/j.ab.2007.02.027. Epub 2007 Feb 24.


Previous conflicting reports suggest that DNase-I binds F-actin with either equal or drastically different K(D) values compared to G-actin. We developed a high-throughput DNase-I inhibition assay to determine the K(D) of DNase-I for F-actin. We confirmed that phalloidin-stabilized F-actin is protected from depolymerization by DNase-I and that the critical concentration at the pointed end of phalloidin-F-actin is 45.5+/-13.9 nM. We found that DNase-I inhibition by actin follows ultrasensitive mechanics. Using varying lengths of gelsolin-capped phalloidin-F-actin, we concluded that the affinities of DNase-I for G- and the pointed end subunits of F-actin are almost indistinguishable, such that DNase-I may not distinguish between G- and F-actin conformations.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actin Cytoskeleton / chemistry
  • Actin Cytoskeleton / drug effects
  • Actin Cytoskeleton / metabolism
  • Actins / chemistry*
  • Actins / classification
  • Actins / metabolism*
  • Animals
  • Binding Sites
  • Deoxyribonuclease I / chemistry
  • Deoxyribonuclease I / metabolism*
  • Models, Chemical
  • Molecular Conformation
  • Polymers / chemistry
  • Polymers / metabolism
  • Protein Binding
  • Spectrometry, Fluorescence


  • Actins
  • Polymers
  • Deoxyribonuclease I