Surface-exposed cysteine residues are of interest in industrial applications because they tend to form disulfide bridges with other molecules, disrupting the stability of the original protein.

The following example shows one way to study cysteines in a protein structure:

  1. Launch Protean 3D and open any desired structure file.
  1. Open the Composition report and select all cysteines by clicking on the CYS row.
  1. Choose a Fill color for the cysteines (View > Style > Color), that will differentiate them from the colors used to show surfaces. Bright green, blue or yellow are good options.
  1. Apply a surface (View > Explorer > Surfaces).
  1. Rotate and visually examine the structure in the Structure view to detect the surface-exposed cysteines. In the image below, the cysteine residue is shown in green.

  1. To confirm the visual analysis, select each cysteine residue in the Structure view and refer to the Details panel (View > Details) for relevant statistics.

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