Reversible unfolding of individual titin immunoglobulin domains by AFM

Science. 1997 May 16;276(5315):1109-12. doi: 10.1126/science.276.5315.1109.

Abstract

Single-molecule atomic force microscopy (AFM) was used to investigate the mechanical properties of titin, the giant sarcomeric protein of striated muscle. Individual titin molecules were repeatedly stretched, and the applied force was recorded as a function of the elongation. At large extensions, the restoring force exhibited a sawtoothlike pattern, with a periodicity that varied between 25 and 28 nanometers. Measurements of recombinant titin immunoglobulin segments of two different lengths exhibited the same pattern and allowed attribution of the discontinuities to the unfolding of individual immunoglobulin domains. The forces required to unfold individual domains ranged from 150 to 300 piconewtons and depended on the pulling speed. Upon relaxation, refolding of immunoglobulin domains was observed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adsorption
  • Connectin
  • Elasticity
  • Entropy
  • Immunoglobulins / chemistry*
  • Microscopy, Atomic Force
  • Monte Carlo Method
  • Muscle Proteins / chemistry*
  • Protein Folding*
  • Protein Kinases / chemistry*
  • Protein Structure, Tertiary
  • Recombinant Proteins / chemistry
  • Stress, Mechanical
  • Thermodynamics

Substances

  • Connectin
  • Immunoglobulins
  • Muscle Proteins
  • Recombinant Proteins
  • Protein Kinases