Recognition Force Spectroscopy Studies of the NTA-His6 Bond

✍ Scribed by Ferry Kienberger; Gerald Kada; Hermann J. Gruber; Vassili Ph. Pastushenko; Christian Riener; Maria Trieb; Hans-Günter Knaus; Hansgeorg Schindler; Peter Hinterdorfer

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 181 KB
• Volume: 1
• Category: Article
• ISSN: 1438-5163
• DOI: 10.1002/(sici)1438-5171(200004)1:1<59::aid-simo59>3.0.co;2-v

✦ Synopsis

Molecular recognition of single NTA-His6 pairs was detected with the atomic force microscope. The force required to dissociate a NTA-His6 bond (unbinding force) was logarithmically dependent on the loading rate of the experiment and varied from 150 pN at 4.5 nN/s to 194 pN at 70 nN/s. Blocking experiments with imidazol clearly demonstrated the specificity of the detected recognition events. The lifetime of the NTA-His6 bond decreased with increasing loading force, from 17 ms at 150 pN to 2.5 ms at 194 pN. Extrapolation with a Boltzmann ansatz lead to 15 s lifetime at zero force. The bond length of the NTA-His6 binding pocket was estimated to be in the range of 0.2 nm. Since the interaction force of NTA-His6 is considerably higher than the typical binding strength of other receptorligand systems it appears to be ideally suited as a general tool to anchor ligands to AFM tips for recognition force microscopy/spectroscopy experiments.