Single-molecule lysozyme dynamics monitored by an electronic circuit

Science. 2012 Jan 20;335(6066):319-24. doi: 10.1126/science.1214824.

Abstract

Tethering a single lysozyme molecule to a carbon nanotube field-effect transistor produced a stable, high-bandwidth transducer for protein motion. Electronic monitoring during 10-minute periods extended well beyond the limitations of fluorescence techniques to uncover dynamic disorder within a single molecule and establish lysozyme as a processive enzyme. On average, 100 chemical bonds are processively hydrolyzed, at 15-hertz rates, before lysozyme returns to its nonproductive, 330-hertz hinge motion. Statistical analysis differentiated single-step hinge closure from enzyme opening, which requires two steps. Seven independent time scales governing lysozyme's activity were observed. The pH dependence of lysozyme activity arises not from changes to its processive kinetics but rather from increasing time spent in either nonproductive rapid motions or an inactive, closed conformation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Bacteriophage T4 / enzymology
  • Biocatalysis
  • Electric Conductivity
  • Fluorescence Resonance Energy Transfer
  • Hydrogen-Ion Concentration
  • Kinetics
  • Microscopy, Atomic Force
  • Muramidase / chemistry*
  • Muramidase / metabolism*
  • Nanotubes, Carbon
  • Peptidoglycan / metabolism
  • Protein Conformation
  • Pyrenes
  • Static Electricity
  • Thermodynamics
  • Transistors, Electronic

Substances

  • Nanotubes, Carbon
  • Peptidoglycan
  • Pyrenes
  • Muramidase