Yardstick Measures Cysteines On The Move | Chemical & Engineering News
Volume 89 Issue 41 | p. 40 | Concentrates
Issue Date: October 10, 2011

Yardstick Measures Cysteines On The Move

Fate of one cysteine among many is detectable with atomic force microscopy
Department: Science & Technology
News Channels: Analytical SCENE, Biological SCENE
Keywords: Atomic force microscopy, protein folding, disulfide bonds, nanotechnology, kinetics
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Extending Knowledge
An AFM tip unsheathes reactive Cys32 and monitors whether it reacts with Cys24 or Cys55, or is beaten by an external nucleophile.
An AFM tip unsheaths reactive Cys32 and monitors whether it reacts with Cys24 or Cys55, or is beaten by an external nucleophile.
 
Extending Knowledge
An AFM tip unsheathes reactive Cys32 and monitors whether it reacts with Cys24 or Cys55, or is beaten by an external nucleophile.

Relying on tiny tugs from an atomic force microscope, a new technique shows promise for measuring the dynamics of cysteine residues’ reactivity in proteins (Nat. Chem., DOI: 10.1038/nchem.1155). Many proteins derive structural integrity from multiple disulfide bonds between cysteine residues. But in nascent or actively folding proteins, cysteines are on the move, pairing transiently before switching partners in the search for a stable configuration. Julio M. Fernández of Columbia University and colleagues sought to disentangle the dynamics of an individual cysteine in this type of complex environment. They tethered a section of the muscle protein titin containing multiple disulfides to a custom atomic force microscopy (AFM) setup and yanked on it in the presence of a nucleophile to uncage a reactive cysteine thiol group. They could tell which of the two sulfur atoms in a nearby disulfide was attacked by the cysteine through AFM measurements, which revealed how far the resulting protein product could extend. The team says its technique could also be used to monitor competing pathways in other reactions that involve thiol groups.

 
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